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Requesting advise about conversion of images.

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  • Ron R
    Hi listers. I m in the proces of preparing maps for a PDA (Mio168) that I hope to receive one of these days. So basically converting through Img2ozf. If I have
    Message 1 of 19 , May 1 7:42 AM
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      Hi listers.
      I'm in the proces of preparing maps for a PDA (Mio168) that I hope to
      receive one of these days.
      So basically converting through Img2ozf.

      If I have an image available in *.tif (either scanned by myself or from an
      other source), I will keep the original stored at a save place, using a
      *.png -version. So if I want to alter something in the image ( i.e. add a
      road/track I've been driving wich is not on the image) I go back to the
      *.tif, change what I want to change, convert to *.png again and use that
      image again.
      This because *.png files are rather small (compared to tif) whilst - at
      least for me - it's impossible to see any difference between *.tiff and
      *.png.
      I have to admit that I use a mild compression, but *.png -files often are
      about half the size of a *.tif-file.

      Being *.tif the most 'prestine' image I've already converted quite some
      files into ozf2-format.
      Just because I was curious about the differences I also converted a
      *.png-version of one of the tiff-files into ozf2 today.
      And lo and behold, this new ozf2-file created from the *.png was much
      smaller than the ozf2-file created from the *.tiff!!!
      I expected them to be the same size, assuming the *.png-image in memory is
      unpacked to the 'original' image (= same as tif-image) and than converted to
      ozf2
      I then opened both the ozf2-files in OziExplorer and, apart from a shade of
      difference in 'flat' colors (i.e. the blue of seawater), I can see no
      apparent differences.
      As I have no PDA yet I cannot compare in that environment and before going
      throught all the hassle of conversion, my question is:
      Do I have to expect any disadvantages in using a ozf2 file created from a
      *.png (or even *.jpg)?
      For your info some figures:
      Original tif (8-bit colors): 13.390 Kb resulting ozf2: 13.979 Kb (48 diff
      colors)
      *.png (8-bit colors) from original tif: 6.478 Kb, resulting ozf2: 7.884 Kb
      (48 colors).

      Thanks for your comments,
      Ron R
    • Dave Patton [DCP]
      ... Open the TIFF image in IrfanView, and check the Image Information. In particular, not the info about the colors. Now use IrfanView to save the TIFF as a
      Message 2 of 19 , May 1 7:52 AM
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        Ron R wrote:
        > If I have an image available in *.tif (either scanned by myself or from an
        > other source), I will keep the original stored at a save place, using a
        > *.png -version.

        > This because *.png files are rather small (compared to tif) whilst - at
        > least for me - it's impossible to see any difference between *.tiff and
        > *.png.
        > I have to admit that I use a mild compression, but *.png -files often are
        > about half the size of a *.tif-file.

        > Original tif (8-bit colors): 13.390 Kb resulting ozf2: 13.979 Kb (48 diff
        > colors)
        > *.png (8-bit colors) from original tif: 6.478 Kb, resulting ozf2: 7.884 Kb
        > (48 colors).

        Open the TIFF image in IrfanView, and check the Image Information.
        In particular, not the info about the colors.
        Now use IrfanView to save the TIFF as a PNG, and select
        max compression(9). Reduce the TIFF color depth(don't save
        the TIFF), and create another PNG.
        I suspect you'll find the size differences may be due to the
        number of colors in the image.

        --
        Dave Patton
        Canadian Coordinator, Degree Confluence Project
        http://www.confluence.org/
        My website: http://members.shaw.ca/davepatton/
      • rwcx183
        ... at ... and ... As well you shouldn t see any difference, since both formats use perfect lossless compression. ... often are ... I m not sure what you mean
        Message 3 of 19 , May 1 9:23 AM
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          --- In OziUsers-L@yahoogroups.com, "Ron R" <r.reijnders@h...> wrote:
          > This because *.png files are rather small (compared to tif) whilst -
          at
          > least for me - it's impossible to see any difference between *.tiff
          and
          > *.png.

          As well you shouldn't see any difference, since both formats use
          perfect lossless compression.

          > I have to admit that I use a mild compression, but *.png -files
          often are
          > about half the size of a *.tif-file.

          I'm not sure what you mean by "mild compression". Both .png
          and .tiff formats can use compression. No clear advantage between
          the two. Here's a file size comparison that I did a while back:

          original 8 bit color (12 colors used) .tif file with no compression
          was 25826770 bytes

          same file saved as .tif using packbits compression is 3941206 bytes

          same file saved as .tif using LZW compression is 1798130 bytes

          same file saved as .png is 1689914 bytes

          That's not a huge savings for the .png format, some of which can be
          accounted for, due to the fact that .png format doesn't carry the
          geotiff info. Now, Ozi does not support LZW compressed .tif files
          unless you install the auslig.zip file from the OziExplorer optional
          extras page.

          >
          > Being *.tif the most 'prestine' image I've already converted quite
          some
          > files into ozf2-format.
          > Just because I was curious about the differences I also converted a
          > *.png-version of one of the tiff-files into ozf2 today.
          > And lo and behold, this new ozf2-file created from the *.png was
          much
          > smaller than the ozf2-file created from the *.tiff!!!
          > I expected them to be the same size, assuming the *.png-image in
          memory is
          > unpacked to the 'original' image (= same as tif-image) and than
          converted to
          > ozf2
          > I then opened both the ozf2-files in OziExplorer and, apart from a
          shade of
          > difference in 'flat' colors (i.e. the blue of seawater), I can see
          no
          > apparent differences.

          Unless you've messed with the number of colors setting, you shouldn't
          see ANY difference in the appearance of the .ozf2 image.

          In the interest of science, I took the previously mentioned .tif
          and .png files and converted them to .ozf2. I did not check the
          boxes "initial resize", or "number of colors". All of the .tif
          files, no matter which lossless compression method was used, resulted
          in .ozf2 files with identical file size of 2060889. So, we actually
          got a net file size INCREASE by converting to .ozf2!!!! The .png
          file when converted to .ozf2 resulted in a very slightly smaller file
          size of 2053835. This is quite different from your results. Now,
          bear in mind that although we did get a file size increase, there are
          mitigating circumstances here. .ozf2 files contain multiple copies
          of the image at different "zoom" levels. This speeds up changing
          zoom levels, though you may not notice it on a PC. We don't have any
          way to compare changing zoom levels on a PDA, since OziCE only
          supports .ozf format. Also, Des Newman did not invent some new
          fantastic compression scheme in the .ozf2 format. So, we shouldn't
          expect better compression from .ozf2 format.

          J.G.
        • Ron R
          J.G and Dave, In the conversion process I used Irfanview and Img2ozf. Nothing else, ... From: rwcx183 To:
          Message 4 of 19 , May 1 12:24 PM
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            J.G and Dave,
            In the conversion process I used Irfanview and Img2ozf. Nothing else,

            ----- Original Message -----
            From: "rwcx183" <lgalvin@...>
            To: <OziUsers-L@yahoogroups.com>
            Sent: Sunday, May 01, 2005 6:23 PM
            Subject: [OziUsers-L] Re: Requesting advise about conversion of images.


            > --- In OziUsers-L@yahoogroups.com, "Ron R" <r.reijnders@h...> wrote:
            >> This because *.png files are rather small (compared to tif) whilst -
            > at
            >> least for me - it's impossible to see any difference between *.tiff
            > and
            >> *.png.
            >
            > As well you shouldn't see any difference, since both formats use
            > perfect lossless compression.
            >
            >> I have to admit that I use a mild compression, but *.png -files
            > often are
            >> about half the size of a *.tif-file.
            >
            > I'm not sure what you mean by "mild compression". Both .png
            > and .tiff formats can use compression. No clear advantage between
            > the two.

            The info from the original tif file states that LZW-compression has been
            used:
            Image size 10400x5000 pixels = 52.001.64 Bytes
            filesize on disk: **13.711.864 Bytes.**
            original Colors: 256 colors at present: 256 (so the 8-bit info is fully
            used I think)

            I used Irfanview for a straightforward conversion, maintaining the amount of
            colors (as far as I'm aware ;-) )

            I used a compression rate of 6 (whatever that may be, max is 9) in Irfanview
            to convert to PNG:
            Info from Irfanview about this PNG:
            compression: PNG-zip
            Image size 10400x5000 pixels = 52.00 Mpixel
            filesize on disk **6.634.314 Bytes**.
            original Colors: 256 colors at present: 256

            I have no idea how I can get to the ozf2 file information

            > Here's a file size comparison that I did a while back:
            >
            > original 8 bit color (12 colors used) .tif file with no compression
            > was 25826770 bytes
            >
            > same file saved as .tif using packbits compression is 3941206 bytes
            >
            > same file saved as .tif using LZW compression is 1798130 bytes

            This reduction using LZW compression is understandable

            >
            > same file saved as .png is 1689914 bytes

            What compression did you use here? max (9) or none (0)?

            > That's not a huge savings for the .png format, some of which can be
            > accounted for, due to the fact that .png format doesn't carry the
            > geotiff info. Now, Ozi does not support LZW compressed .tif files
            > unless you install the auslig.zip file from the OziExplorer optional
            > extras page.
            >
            No geotiff info is incorporated in the file. It's a plain image.

            >>
            >> Being *.tif the most 'prestine' image I've already converted quite
            > some
            >> files into ozf2-format.
            >> Just because I was curious about the differences I also converted a
            >> *.png-version of one of the tiff-files into ozf2 today.
            >> And lo and behold, this new ozf2-file created from the *.png was
            > much
            >> smaller than the ozf2-file created from the *.tiff!!!
            >> I expected them to be the same size, assuming the *.png-image in
            > memory is
            >> unpacked to the 'original' image (= same as tif-image) and than
            > converted to
            >> ozf2
            >> I then opened both the ozf2-files in OziExplorer and, apart from a
            > shade of
            >> difference in 'flat' colors (i.e. the blue of seawater), I can see
            > no
            >> apparent differences.
            >
            > Unless you've messed with the number of colors setting, you shouldn't
            > see ANY difference in the appearance of the .ozf2 image.

            I've changed the amount of colors, but that was during the conversion to
            ozf2 **and for both the tif -->ozf2 and png-->ozf2**.
            At that point I used the preset value in img2ozf: 48 colors.
            As said, the results for me were staggering: from tiff--> ozf2 file is
            almost 14 Mb, from the png--> 7.8, say 8 Mb.

            >
            > In the interest of science, I took the previously mentioned .tif
            > and .png files and converted them to .ozf2. I did not check the
            > boxes "initial resize", or "number of colors". All of the .tif
            > files, no matter which lossless compression method was used, resulted
            > in .ozf2 files with identical file size of 2060889. So, we actually
            > got a net file size INCREASE by converting to .ozf2!!!! The .png
            > file when converted to .ozf2 resulted in a very slightly smaller file
            > size of 2053835.

            In the img2ozf-help file this is mentioned. One can expect a slightly larger
            that original file due to the zoom-function.
            I assume that in certain cases of color reduction (say the original has 16,7
            million colors) to say 48 colors, the ozf2 could be a bit smaller, though
            normally not.

            > This is quite different from your results.
            Can only agree here.

            Now,
            > bear in mind that although we did get a file size increase, there are
            > mitigating circumstances here. .ozf2 files contain multiple copies
            > of the image at different "zoom" levels. This speeds up changing
            > zoom levels, though you may not notice it on a PC. We don't have any
            > way to compare changing zoom levels on a PDA, since OziCE only
            > supports .ozf format. Also, Des Newman did not invent some new
            > fantastic compression scheme in the .ozf2 format. So, we shouldn't
            > expect better compression from .ozf2 format.
            >
            > J.G.
            >
            Aware of all of this.
            But the question remains: should I go on tiff -- png -- ozf2 or do I have to
            expect trubbles once I'll use these files in the Mio 168?

            Anyway, thanks for the explanation,
            Ron R
          • rwcx183
            ... else, ... I used PaintShop Pro and Img2ozf. ... images. ... whilst - ... *.tiff ... been ... fully ... amount of ... Yes, compression used with .png files
            Message 5 of 19 , May 1 2:42 PM
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              --- In OziUsers-L@yahoogroups.com, "Ron R" <r.reijnders@h...> wrote:
              > J.G and Dave,
              > In the conversion process I used Irfanview and Img2ozf. Nothing
              else,
              >

              I used PaintShop Pro and Img2ozf.

              > ----- Original Message -----
              > From: "rwcx183" <lgalvin@p...>
              > To: <OziUsers-L@yahoogroups.com>
              > Sent: Sunday, May 01, 2005 6:23 PM
              > Subject: [OziUsers-L] Re: Requesting advise about conversion of
              images.
              >
              >
              > > --- In OziUsers-L@yahoogroups.com, "Ron R" <r.reijnders@h...>
              wrote:
              > >> This because *.png files are rather small (compared to tif)
              whilst -
              > > at
              > >> least for me - it's impossible to see any difference between
              *.tiff
              > > and
              > >> *.png.
              > >
              > > As well you shouldn't see any difference, since both formats use
              > > perfect lossless compression.
              > >
              > >> I have to admit that I use a mild compression, but *.png -files
              > > often are
              > >> about half the size of a *.tif-file.
              > >
              > > I'm not sure what you mean by "mild compression". Both .png
              > > and .tiff formats can use compression. No clear advantage between
              > > the two.
              >
              > The info from the original tif file states that LZW-compression has
              been
              > used:
              > Image size 10400x5000 pixels = 52.001.64 Bytes
              > filesize on disk: **13.711.864 Bytes.**
              > original Colors: 256 colors at present: 256 (so the 8-bit info is
              fully
              > used I think)
              >
              > I used Irfanview for a straightforward conversion, maintaining the
              amount of
              > colors (as far as I'm aware ;-) )

              Yes, compression used with .png files is always lossless and unless
              you explicitly reduced the color count in IrfanView, it should have
              maintained the full 256 colors.

              >
              > I used a compression rate of 6 (whatever that may be, max is 9) in
              Irfanview
              > to convert to PNG:
              > Info from Irfanview about this PNG:
              > compression: PNG-zip
              > Image size 10400x5000 pixels = 52.00 Mpixel
              > filesize on disk **6.634.314 Bytes**.
              > original Colors: 256 colors at present: 256

              I am quite surprised that the .png compression techniques worked
              twice as well as LZW tiff. I suppose that it must have something to
              do with the nature of the image.

              >
              > I have no idea how I can get to the ozf2 file information
              >
              > > Here's a file size comparison that I did a while back:
              > >
              > > original 8 bit color (12 colors used) .tif file with no
              compression
              > > was 25826770 bytes
              > >
              > > same file saved as .tif using packbits compression is 3941206
              bytes
              > >
              > > same file saved as .tif using LZW compression is 1798130 bytes
              >
              > This reduction using LZW compression is understandable
              >
              > >
              > > same file saved as .png is 1689914 bytes
              >
              > What compression did you use here? max (9) or none (0)?

              Actually, I had forgotten entirely, that the compression level was
              adjustable with .png and apparently it isn't, in PaintShop Pro. I
              went back and redid the test with Irfanview and I got the following:

              compression level file size
              0 25867333
              1 2685007
              2 2462621
              3 2219317
              4 2072275
              5 1924343
              6 1729814
              7 1693276
              8 1620836
              9 1544117

              So, the very highest (still lossless) level of compression, eeks out
              a slightly larger advantage over LZW .tif.


              >
              > > That's not a huge savings for the .png format, some of which can
              be
              > > accounted for, due to the fact that .png format doesn't carry the
              > > geotiff info. Now, Ozi does not support LZW compressed .tif files
              > > unless you install the auslig.zip file from the OziExplorer
              optional
              > > extras page.
              > >
              > No geotiff info is incorporated in the file. It's a plain image.

              I was referring to the image with which I was working and not trying
              to explain the 2:1 difference that you saw.

              >
              > >>
              > >> Being *.tif the most 'prestine' image I've already converted
              quite
              > > some
              > >> files into ozf2-format.
              > >> Just because I was curious about the differences I also
              converted a
              > >> *.png-version of one of the tiff-files into ozf2 today.
              > >> And lo and behold, this new ozf2-file created from the *.png was
              > > much
              > >> smaller than the ozf2-file created from the *.tiff!!!
              > >> I expected them to be the same size, assuming the *.png-image in
              > > memory is
              > >> unpacked to the 'original' image (= same as tif-image) and than
              > > converted to
              > >> ozf2
              > >> I then opened both the ozf2-files in OziExplorer and, apart from
              a
              > > shade of
              > >> difference in 'flat' colors (i.e. the blue of seawater), I can
              see
              > > no
              > >> apparent differences.
              > >
              > > Unless you've messed with the number of colors setting, you
              shouldn't
              > > see ANY difference in the appearance of the .ozf2 image.
              >
              > I've changed the amount of colors, but that was during the
              conversion to
              > ozf2 **and for both the tif -->ozf2 and png-->ozf2**.
              > At that point I used the preset value in img2ozf: 48 colors.
              > As said, the results for me were staggering: from tiff--> ozf2 file
              is
              > almost 14 Mb, from the png--> 7.8, say 8 Mb.

              It might be interesting to see the results, if you didn't reduce the
              color count in the ozf2 conversion process.

              >
              > >
              > > In the interest of science, I took the previously mentioned .tif
              > > and .png files and converted them to .ozf2. I did not check the
              > > boxes "initial resize", or "number of colors". All of the .tif
              > > files, no matter which lossless compression method was used,
              resulted
              > > in .ozf2 files with identical file size of 2060889. So, we
              actually
              > > got a net file size INCREASE by converting to .ozf2!!!! The .png
              > > file when converted to .ozf2 resulted in a very slightly smaller
              file
              > > size of 2053835.
              >
              > In the img2ozf-help file this is mentioned. One can expect a
              slightly larger
              > that original file due to the zoom-function.
              > I assume that in certain cases of color reduction (say the original
              has 16,7
              > million colors) to say 48 colors, the ozf2 could be a bit smaller,
              though
              > normally not.

              Just to be thorough, I went ahead and converted the .png images that
              I had previously created at each of the compression levels, to .ozf2
              format. Precisely as expected, the result was a file size of 2060889
              bytes in every case.

              >
              > > This is quite different from your results.
              > Can only agree here.
              >
              > Now,
              > > bear in mind that although we did get a file size increase, there
              are
              > > mitigating circumstances here. .ozf2 files contain multiple
              copies
              > > of the image at different "zoom" levels. This speeds up changing
              > > zoom levels, though you may not notice it on a PC. We don't have
              any
              > > way to compare changing zoom levels on a PDA, since OziCE only
              > > supports .ozf format. Also, Des Newman did not invent some new
              > > fantastic compression scheme in the .ozf2 format. So, we
              shouldn't
              > > expect better compression from .ozf2 format.
              > >
              > > J.G.
              > >
              > Aware of all of this.
              > But the question remains: should I go on tiff -- png -- ozf2 or do
              I have to
              > expect trubbles once I'll use these files in the Mio 168?

              I don't know what to recommend here, since the result seems to be
              somewhat image dependent and perhaps also dependent on the color
              count reduction. Since you're keeping the original .tif files, I
              would convert from both .png and .tif, keeping which ever resulted in
              a smaller .ozf2. At this point, I wouldn't make any predictions
              about which would work better.

              J.G.
            • Ron R
              I ll be snipping al lot of the story to make it more readable, and to be honest, I don t have a lot to add. ;-) ... From: rwcx183 To:
              Message 6 of 19 , May 2 12:09 AM
              • 0 Attachment
                I'll be snipping al lot of the story to make it more readable, and to be
                honest, I don't have a lot to add. ;-)
                ----- Original Message -----
                From: "rwcx183" <lgalvin@...>
                To: <OziUsers-L@yahoogroups.com>
                Sent: Sunday, May 01, 2005 11:42 PM
                Subject: [OziUsers-L] Re: Requesting advise about conversion of images.


                > --- In OziUsers-L@yahoogroups.com, "Ron R" <r.reijnders@h...> wrote:
                >> J.G and Dave,
                >> In the conversion process I used Irfanview and Img2ozf. Nothing
                > else,
                >>
                >
                > I used PaintShop Pro and Img2ozf.
                [snip]
                > wrote:
                >> >> This because *.png files are rather small (compared to tif)
                > whilst -
                >> > at
                >> >
                [snip image info]

                >> I used Irfanview for a straightforward conversion, maintaining the
                > amount of
                >> colors (as far as I'm aware ;-) )
                >
                > Yes, compression used with .png files is always lossless and unless
                > you explicitly reduced the color count in IrfanView, it should have
                > maintained the full 256 colors.
                >
                That's why I use PNG, because it's supposed to be lossless.
                Thinking about this, if the Pc-performance permits, one should always use
                the highest compression possible. This saves disk (or memeorycard) -space.

                >>
                >> I used a compression rate of 6 (whatever that may be, max is 9) in
                > Irfanview
                >> to convert to PNG:
                >> Info from Irfanview about this PNG:
                >> compression: PNG-zip
                >> Image size 10400x5000 pixels = 52.00 Mpixel
                >> filesize on disk **6.634.314 Bytes**.
                >> original Colors: 256 colors at present: 256
                >
                > I am quite surprised that the .png compression techniques worked
                > twice as well as LZW tiff. I suppose that it must have something to
                > do with the nature of the image.
                >
                I didn't bother about the image, I just took a large image.
                Looking into this, it's an image of an island with large, broad beaches and
                not many features.
                You can have a very valid point here.

                >>
                >> I have no idea how I can get to the ozf2 file information
                >>
                [snip]
                >>
                >> What compression did you use here? max (9) or none (0)?
                >
                > Actually, I had forgotten entirely, that the compression level was
                > adjustable with .png and apparently it isn't, in PaintShop Pro. I
                > went back and redid the test with Irfanview and I got the following:
                >
                > compression level file size
                > 0 25867333
                > 1 2685007
                > 2 2462621
                > 3 2219317
                > 4 2072275
                > 5 1924343
                > 6 1729814
                > 7 1693276
                > 8 1620836
                > 9 1544117
                >
                > So, the very highest (still lossless) level of compression, eeks out
                > a slightly larger advantage over LZW .tif.
                >
                Still remarkable that my png-file was about half the original tif
                (LZW-compressed) file, at a compression rate of 6 <;-)
                >
                >>
                [snip text about using colorreduction]
                >> At that point I used the preset value in img2ozf: 48 colors.
                >> As said, the results for me were staggering: from tiff--> ozf2 file
                > is
                >> almost 14 Mb, from the png--> 7.8, say 8 Mb.
                >
                > It might be interesting to see the results, if you didn't reduce the
                > color count in the ozf2 conversion process.
                >
                >>
                [snip about file size when converting to ozf2]

                >> I assume that in certain cases of color reduction (say the original
                > has 16,7
                >> million colors) to say 48 colors, the ozf2 could be a bit smaller,
                > though
                >> normally not.
                >
                > Just to be thorough, I went ahead and converted the .png images that
                > I had previously created at each of the compression levels, to .ozf2
                > format. Precisely as expected, the result was a file size of 2060889
                > bytes in every case.
                >
                >>
                >> > This is quite different from your results.
                >> Can only agree here.
                >>
                >> Now,
                >> > bear in mind that although we did get a file size increase, there
                > are
                >> > mitigating circumstances here. .ozf2 files contain multiple
                > copies
                >> > of the image at different "zoom" levels. This speeds up changing
                >> > zoom levels, though you may not notice it on a PC. We don't have
                > any
                >> > way to compare changing zoom levels on a PDA, since OziCE only
                >> > supports .ozf format. Also, Des Newman did not invent some new
                >> > fantastic compression scheme in the .ozf2 format. So, we
                > shouldn't
                >> > expect better compression from .ozf2 format.
                >> >
                >> > J.G.
                >> >
                >> Aware of all of this.
                >> But the question remains: should I go on tiff -- png -- ozf2 or do
                > I have to
                >> expect trubbles once I'll use these files in the Mio 168?
                >
                > I don't know what to recommend here, since the result seems to be
                > somewhat image dependent and perhaps also dependent on the color
                > count reduction. Since you're keeping the original .tif files, I
                > would convert from both .png and .tif, keeping which ever resulted in
                > a smaller .ozf2. At this point, I wouldn't make any predictions
                > about which would work better.
                >
                > J.G,
                you invested quite some time on testing and replying on this scale.
                Sadly (for this conversation) I'll leave in about an hour for work for about
                a week and will probably have limited time and internet-acces.
                I will be taking my laptop with me though ;-)
                Hope to do some testing myself.
                Thanks a lot,
                Ron R
              • Piet Vogelaar
                ... From Ozi CE page: Note: Not all image formats can be used in OziExplorerCE. The images must be converted to .ozf2 format using the Img2Ozf Converter or
                Message 7 of 19 , May 2 1:05 AM
                • 0 Attachment
                  I will snip the lot:


                  > >> Now,
                  > >> > bear in mind that although we did get a file size increase, there
                  > > are
                  > >> > mitigating circumstances here. .ozf2 files contain multiple
                  > > copies
                  > >> > of the image at different "zoom" levels. This speeds up changing
                  > >> > zoom levels, though you may not notice it on a PC. We don't have
                  > > any
                  > >> > way to compare changing zoom levels on a PDA, since OziCE only
                  > >> > supports .ozf format.

                  From Ozi CE page:
                  Note: Not all image formats can be used in OziExplorerCE. The images must be
                  converted to .ozf2 format using the Img2Ozf Converter or must be in ECW
                  format (development version only). Due to its high compression, the ECW
                  format is a slower format to load on a PDA.

                  Piet
                • Johnny Doe
                  ... Ron, there is no reason to keep a png version, if you have a tiff file. There are 26 registered compression algorithms in tiff, one of them
                  Message 8 of 19 , May 2 1:56 AM
                  • 0 Attachment
                    --- Ron R <r.reijnders@...> wrote:
                    >
                    > If I have an image available in *.tif (either
                    > scanned by myself or from an
                    > other source), I will keep the original stored at a
                    > save place, using a
                    > *.png -version.

                    Ron,

                    there is no reason to keep a png version, if you
                    have a tiff file.
                    There are 26 "registered" compression algorithms in
                    tiff, one of
                    them (COMPRESS_DEFLATE) is the same used by png.
                    The main advantage of tiff is the ability to save
                    the data in
                    tiles and to have the "previews". Img2ozf is using
                    libtiff
                    internally, so ozice _could_ have used tiff as a
                    native format.
                    The reasons for not doing that are obviously
                    nontechnical.



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                  • Johnny Doe
                    ... Deflate (zip) algorithm is usually better than LZW. ... There is some code included in the GPSMapedit source to read ozf2 files. ozf2 looks like a really
                    Message 9 of 19 , May 2 2:04 AM
                    • 0 Attachment
                      --- rwcx183 <lgalvin@...> wrote:
                      >
                      > I am quite surprised that the .png compression
                      > techniques worked
                      > twice as well as LZW tiff. I suppose that it must
                      > have something to
                      > do with the nature of the image.
                      >

                      Deflate (zip) algorithm is usually better than LZW.

                      > >
                      > > I have no idea how I can get to the ozf2 file
                      > information
                      > >

                      There is some code included in the GPSMapedit source
                      to read ozf2 files. ozf2 looks like a really
                      bastardized tiff,
                      and probably uses the tiles compressed with packbits.



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                    • rwcx183
                      ... Do you have a reference for the claim that (COMPRESS_DEFLATE) is the compression method used by the .png format? I m aware of it s use with .tiff images,
                      Message 10 of 19 , May 2 7:29 AM
                      • 0 Attachment
                        --- In OziUsers-L@yahoogroups.com, Johnny Doe <uucp1@y...> wrote:
                        >
                        > --- Ron R <r.reijnders@h...> wrote:
                        > >
                        > > If I have an image available in *.tif (either
                        > > scanned by myself or from an
                        > > other source), I will keep the original stored at a
                        > > save place, using a
                        > > *.png -version.
                        >
                        > Ron,
                        >
                        > there is no reason to keep a png version, if you
                        > have a tiff file.
                        > There are 26 "registered" compression algorithms in
                        > tiff, one of
                        > them (COMPRESS_DEFLATE) is the same used by png.
                        > The main advantage of tiff is the ability to save
                        > the data in
                        > tiles and to have the "previews". Img2ozf is using
                        > libtiff
                        > internally, so ozice _could_ have used tiff as a
                        > native format.
                        > The reasons for not doing that are obviously
                        > nontechnical.

                        Do you have a reference for the claim that (COMPRESS_DEFLATE) is the
                        compression method used by the .png format? I'm aware of it's use
                        with .tiff images, but there, it's unwelcome due to poor
                        compatibility. Of the couple dozen image viewing/editing programs
                        that I have, exactly one of them can read a deflate compressed tiff
                        image. Certainly OziExplorer cannot.

                        The main advantage of tiff may be the ability to save data in tiles,
                        but OziExplorer does not like "tiled" tiffs. Strips are what
                        Oziexplorer likes, with packbits or LZW compression. The "preview"
                        capability of tiff format, is unused by OziExplorer.

                        One of the main reasons not to use tiff as a native format, probably
                        had to do with the need to maintain copy/print protection, as many
                        map images in proprietary formats do not allow conversion, unless the
                        target format maintains the original's copy/print conversion.
                        Security through obscurity, but still, effective enough for the
                        application.

                        The chief disadvantage of .png format with OziExplorer, is that the
                        entire image must be read into physical or virtual memory Vs tiff,
                        where only the part to be displayed is read into memory, assuming
                        that the tiff is stored in "strips" and not tiles. This is all not
                        to mention that .png does not support embedded georeferencing data
                        like geotiff does.


                        J.G.
                      • rwcx183
                        ... It may be better, but that s irrelevant since neither OziExplorer nor much of any other affordable mapping program supports deflate compressed tiff files.
                        Message 11 of 19 , May 2 7:42 AM
                        • 0 Attachment
                          --- In OziUsers-L@yahoogroups.com, Johnny Doe <uucp1@y...> wrote:
                          >
                          > --- rwcx183 <lgalvin@p...> wrote:
                          > >
                          > > I am quite surprised that the .png compression
                          > > techniques worked
                          > > twice as well as LZW tiff. I suppose that it must
                          > > have something to
                          > > do with the nature of the image.
                          > >
                          >
                          > Deflate (zip) algorithm is usually better than LZW.

                          It may be better, but that's irrelevant since neither OziExplorer nor
                          much of any other affordable mapping program supports deflate
                          compressed tiff files.

                          >
                          > > >
                          > > > I have no idea how I can get to the ozf2 file
                          > > information
                          > > >
                          >
                          > There is some code included in the GPSMapedit source
                          > to read ozf2 files. ozf2 looks like a really
                          > bastardized tiff,
                          > and probably uses the tiles compressed with packbits.

                          I doubt seriously, that the ozf2 format is using packbits as the
                          compression method, since it demonstrates significantly smaller file
                          sizes (nearly 2:1 Vs packbits), even though it contains multiple
                          copies of the image at different resolutions, compared to a packbits
                          compressed tiff file.

                          One thing that ozf2 format does do, that's been discussed here in the
                          past, is that the lower resolution images copies that it stores, have
                          been subsampled in a more sophisticated manner than simple decimation
                          and this improves map text readability at sub-100% zoom levels. For
                          all other formats (except ECW and MrSID), OziExplorer must subsample
                          on the fly and map text readability suffers to some extent at sub-
                          100% zoom levels.

                          J.G.
                        • Johnny Doe
                          ... libpng, zlib and libtiff are opensource. This is from the png.h header file: /* This is for compression type. PNG 1.0-1.2 only define the single type. */
                          Message 12 of 19 , May 2 8:40 AM
                          • 0 Attachment
                            --- rwcx183 <lgalvin@...> wrote:
                            >
                            > Do you have a reference for the claim that
                            > (COMPRESS_DEFLATE) is the
                            > compression method used by the .png format?

                            libpng, zlib and libtiff are opensource. This is from
                            the png.h header file:

                            /* This is for compression type. PNG 1.0-1.2 only
                            define the single type. */
                            #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method
                            8, 32K window */
                            #define PNG_COMPRESSION_TYPE_DEFAULT
                            PNG_COMPRESSION_TYPE_BASE

                            > Of the couple dozen image
                            > viewing/editing programs
                            > that I have, exactly one of them can read a deflate
                            > compressed tiff
                            > image. Certainly OziExplorer cannot.

                            There is no "technical" excuse for that, because
                            libtiff and zlib are part of the Img2ozf
                            program.

                            > This is all not
                            > to mention that .png does not support embedded
                            > georeferencing data
                            > like geotiff does.
                            >

                            Strange enough, ozf2 also doesn't have this
                            capability.



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                          • Johnny Doe
                            ... I think GIMP http://www.gimp.org is affordable enough for everybody, namely it costs nothing ;-) ... Good point. I don t really know how the 64x64 tiles
                            Message 13 of 19 , May 2 8:48 AM
                            • 0 Attachment
                              --- rwcx183 <lgalvin@...> wrote:
                              >
                              > It may be better, but that's irrelevant since
                              > neither OziExplorer nor
                              > much of any other affordable mapping program
                              > supports deflate
                              > compressed tiff files.
                              >

                              I think GIMP http://www.gimp.org is affordable enough
                              for everybody,
                              namely it costs nothing ;-)

                              >
                              > I doubt seriously, that the ozf2 format is using
                              > packbits as the
                              > compression method, since it demonstrates
                              > significantly smaller file
                              > sizes (nearly 2:1 Vs packbits), even though it
                              > contains multiple
                              > copies of the image at different resolutions,
                              > compared to a packbits
                              > compressed tiff file.
                              >

                              Good point. I don't really know how the 64x64 tiles
                              are compressed
                              in ozf2. But it is advised for tiff images because of
                              the
                              performance issues. Go figure.



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                            • RchrdWebb@aol.com
                              In a message dated 5/2/2005 8:50:00 A.M. Pacific Daylight Time, uucp1@yahoo.com writes: http://www.gimp.org Hello, I would like to use .PDF Files to make a
                              Message 14 of 19 , May 2 9:19 AM
                              • 0 Attachment
                                In a message dated 5/2/2005 8:50:00 A.M. Pacific Daylight Time,
                                uucp1@... writes:

                                http://www.gimp.org


                                Hello,

                                I would like to use .PDF Files to make a paper maps with UTM lines on them.
                                Anyone know of a freebe that will convert those file, so I can use them with
                                Ozi?

                                Thanks;

                                Richard


                                [Non-text portions of this message have been removed]
                              • rwcx183
                                ... I can t argue the affordable part, but certainly GIMP is no mapping program and it destroys any embedded geotiff tags/keys, just like every other
                                Message 15 of 19 , May 2 10:29 AM
                                • 0 Attachment
                                  --- In OziUsers-L@yahoogroups.com, Johnny Doe <uucp1@y...> wrote:
                                  >
                                  > --- rwcx183 <lgalvin@p...> wrote:
                                  > >
                                  > > It may be better, but that's irrelevant since
                                  > > neither OziExplorer nor
                                  > > much of any other affordable mapping program
                                  > > supports deflate
                                  > > compressed tiff files.
                                  > >
                                  >
                                  > I think GIMP http://www.gimp.org is affordable enough
                                  > for everybody,
                                  > namely it costs nothing ;-)
                                  >

                                  I can't argue the affordable part, but certainly GIMP is no mapping
                                  program and it destroys any embedded geotiff tags/keys, just like
                                  every other non-mapping aware image editor out there. Furthermore,
                                  whilst I do have GIMP, I never use it unless there's no other way to
                                  accomplish the task. There's nothing like an easy to use program and
                                  GIMP is nothing like it.

                                  J.G.
                                • rwcx183
                                  ... on them. ... them with ... Richard, It depends greatly on the precise details of the .PDF files in question. With some .pdfs, you can simply use Adobe
                                  Message 16 of 19 , May 3 8:15 PM
                                  • 0 Attachment
                                    --- In OziUsers-L@yahoogroups.com, RchrdWebb@a... wrote:
                                    >
                                    > In a message dated 5/2/2005 8:50:00 A.M. Pacific Daylight Time,
                                    > uucp1@y... writes:
                                    >
                                    > http://www.gimp.org
                                    >
                                    >
                                    > Hello,
                                    >
                                    > I would like to use .PDF Files to make a paper maps with UTM lines
                                    on them.
                                    > Anyone know of a freebe that will convert those file, so I can use
                                    them with
                                    > Ozi?
                                    >
                                    > Thanks;
                                    >
                                    > Richard

                                    Richard,

                                    It depends greatly on the precise details of the .PDF files in
                                    question. With some .pdfs, you can simply use Adobe Acrobat Reader
                                    to do a graphics area selection and then copy/paste it into an image
                                    editing program. With other pdfs, you can "print" them to image
                                    file, using the freeware but clunky to use, Ghostscript program. If
                                    you only have a few images to convert, you may be able to get the job
                                    done using an evaluation version of a commercial "print to file"
                                    utility such as Fineprint or Informatik Image Driver. For either,
                                    you will have to do a bit of math, to get a decent result,
                                    calculating dpi and "paper" sizes, etc. I suppose if you're really
                                    lucky, Ghostscript may be able to read your pdfs directly, but this
                                    fairly rare for pdfs with images. I should mention SnagIt screen
                                    capture program here. Most people shy away from using screen capture
                                    programs in the mistaken belief that you're limited to screen
                                    resolution in a capture. SnagIt can actually scroll both vertically
                                    and horizontally, to capture an area larger than the screen. So, you
                                    can zoom in, to get the detail you want and then have SnagIt scroll
                                    around capturing the whole image in pieces and automatically
                                    reassemble the pieces for you.

                                    No matter how you get the deed done, that's only the beginning, since
                                    you would now need to somehow calibrate the images. It's seems all
                                    too rare that anyone is actually able to determine the particular
                                    projection and parameters used for a given image. If the image
                                    covers a very small area, the projection will probably not make much
                                    difference. If you have an image that covers a few hundred miles in
                                    X and Y dimensions, you'll likely not be happy with the resultant
                                    accuracy from attempting to guess the projection and parameters.

                                    J.G.
                                  • Roger Moseley
                                    wow. I was going to recommend Print Screen Deluxe, but it doesn t scroll. ... From: rwcx183 To: OziUsers-L@yahoogroups.com Sent: Tuesday, May 03, 2005 9:15 PM
                                    Message 17 of 19 , May 4 7:58 AM
                                    • 0 Attachment
                                      wow. I was going to recommend Print Screen Deluxe, but it doesn't scroll.
                                      ----- Original Message -----
                                      From: rwcx183
                                      To: OziUsers-L@yahoogroups.com
                                      Sent: Tuesday, May 03, 2005 9:15 PM
                                      Subject: [OziUsers-L] Re: Requesting advise about conversion of images.


                                      --- In OziUsers-L@yahoogroups.com, RchrdWebb@a... wrote:
                                      >
                                      > In a message dated 5/2/2005 8:50:00 A.M. Pacific Daylight Time,
                                      > uucp1@y... writes:
                                      >
                                      > http://www.gimp.org
                                      >
                                      >
                                      > Hello,
                                      >
                                      > I would like to use .PDF Files to make a paper maps with UTM lines
                                      on them.
                                      > Anyone know of a freebe that will convert those file, so I can use
                                      them with
                                      > Ozi?
                                      >
                                      > Thanks;
                                      >
                                      > Richard

                                      Richard,

                                      It depends greatly on the precise details of the .PDF files in
                                      question. With some .pdfs, you can simply use Adobe Acrobat Reader
                                      to do a graphics area selection and then copy/paste it into an image
                                      editing program. With other pdfs, you can "print" them to image
                                      file, using the freeware but clunky to use, Ghostscript program. If
                                      you only have a few images to convert, you may be able to get the job
                                      done using an evaluation version of a commercial "print to file"
                                      utility such as Fineprint or Informatik Image Driver. For either,
                                      you will have to do a bit of math, to get a decent result,
                                      calculating dpi and "paper" sizes, etc. I suppose if you're really
                                      lucky, Ghostscript may be able to read your pdfs directly, but this
                                      fairly rare for pdfs with images. I should mention SnagIt screen
                                      capture program here. Most people shy away from using screen capture
                                      programs in the mistaken belief that you're limited to screen
                                      resolution in a capture. SnagIt can actually scroll both vertically
                                      and horizontally, to capture an area larger than the screen. So, you
                                      can zoom in, to get the detail you want and then have SnagIt scroll
                                      around capturing the whole image in pieces and automatically
                                      reassemble the pieces for you.

                                      No matter how you get the deed done, that's only the beginning, since
                                      you would now need to somehow calibrate the images. It's seems all
                                      too rare that anyone is actually able to determine the particular
                                      projection and parameters used for a given image. If the image
                                      covers a very small area, the projection will probably not make much
                                      difference. If you have an image that covers a few hundred miles in
                                      X and Y dimensions, you'll likely not be happy with the resultant
                                      accuracy from attempting to guess the projection and parameters.

                                      J.G.





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                                      [Non-text portions of this message have been removed]
                                    • RchrdWebb@aol.com
                                      Thanks J.G. The older version of Ozi would calibrate a scanned map, but I haven t tried it with this 3.95 Version. I have a freebie web page:
                                      Message 18 of 19 , May 4 8:55 AM
                                      • 0 Attachment
                                        Thanks J.G.

                                        The older version of Ozi would calibrate a scanned map, but I haven't tried
                                        it with this 3.95 Version. I have a freebie web page:

                                        _http://www.geocities.com/trail_cam_ (http://www.geocities.com/trail_cam)

                                        So far, these maps have been good enough for hiking and hunting. But of
                                        course, the military handout map were NAD27, and drawn to scale. The Terra Base
                                        II software uses standard map files and ends up as WGS84 because of the .SHP
                                        files and Tiger overlay.

                                        Richard



                                        [Non-text portions of this message have been removed]
                                      • rwcx183
                                        ... haven t tried ... (http://www.geocities.com/trail_cam) ... But of ... The Terra Base ... of the .SHP ... Richard, Yes, Ozi is still able to calibrate a
                                        Message 19 of 19 , May 4 3:29 PM
                                        • 0 Attachment
                                          --- In OziUsers-L@yahoogroups.com, RchrdWebb@a... wrote:
                                          > Thanks J.G.
                                          >
                                          > The older version of Ozi would calibrate a scanned map, but I
                                          haven't tried
                                          > it with this 3.95 Version. I have a freebie web page:
                                          >
                                          > _http://www.geocities.com/trail_cam_
                                          (http://www.geocities.com/trail_cam)
                                          >
                                          > So far, these maps have been good enough for hiking and hunting.
                                          But of
                                          > course, the military handout map were NAD27, and drawn to scale.
                                          The Terra Base
                                          > II software uses standard map files and ends up as WGS84 because
                                          of the .SHP
                                          > files and Tiger overlay.
                                          >
                                          > Richard

                                          Richard,

                                          Yes, Ozi is still able to calibrate a scanned map. It's still a
                                          manual operation though, for which you should know the projection and
                                          parameters, for best results.

                                          J.G.
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