Loading ...
Sorry, an error occurred while loading the content.

Re: Printing Astrophotographs

Expand Messages
  • GordonM
    Thanks Alan. I may be showing my ignorance but in PS I can specify PPI; how do I determine DPI? Gordon
    Message 1 of 25 , Oct 1, 2011
    • 0 Attachment
      Thanks Alan.

      I may be showing my ignorance but in PS I can specify PPI; how do I determine DPI?

      Gordon

      --- In ccd-newastro@yahoogroups.com, "kafuensis" <astrophotonut@...> wrote:
      >
      >
      > Gordon,
      >
      > What you need to ask them is what dpi they want to see, and what color space they want it in, some places like to add the profile themselves although most will want it already added and resized to the dpi they want to see. A lot of places will charge you a "set up" or consider it a "custom" print if they have do all that for you. Also make sure you tell them not to "auto correct" if that is what they normally do, doing an automatic contrast adjustment does not work for astro prints. :-)
      >
      > Alan
      >
      > (In this respect ppi and dpi are not interchangeable, technically speaking. The term ppi is mostly used in describing the image in relation to monitors and screen resolution, and printers tend to deal in dpi which is typically not the same thing. It can all be quite confusing.)
      >
      >
      > --- In ccd-newastro@yahoogroups.com, "GordonM" <gmandell@> wrote:
      > >
      > > Thanks Alan.
      > >
      > > If I wish to use a printing service, in addition to obtaining a printer/paper/ink profile for soft proofing, what questions should I ask before uploading a file? For example, will they be able to tell me what resolution (in ppi) I need to provide for a print of a give size?
      > >
      > > Gordon
      > >
      > > --- In ccd-newastro@yahoogroups.com, "kafuensis" <astrophotonut@> wrote:
      > > >
      > > > That is just telling you the "theoretical" ppi for a print to print out with a certain circle of confusion. Not what to send to the printer. Depending on what printer you want to send it to, you need to resize to that size and the desired dpi. If you print to a high end Epson printer, the desired dpi that the printer driver wants to see is 360. If you print to a Costco printer, they are typically 300dpi. Actually Costco has pretty good printing, I get a slightly better print from my Epson 4880 but unless you know what you are looking at or see them side by side they both look great. I used to use Costco all the time, now I do a lot of it myself. The Canon printers are typically 240dpi at the driver side.
      > > >
      > > > The Costco profiles are available on a site called DryCreekPhoto, they also have a really good description of how to apply profiles and how to prep your images for printing at Costco. They also tell you how to soft proof.
      > > >
      > > > As to desired ppi for an image to print at a certain size, a lot depends on how you resize. You are not going to print an image from 1mp camera at 12x18 without signs of enlargement when viewed closely. That is what the viewing distance is all about.
      > > >
      > > > A detailed explanation of this complex subject is not really practical on this site, but there is volumes available on the web.
      > > >
      > > > In the end a lot of it is trial and error and the best thing to do is to print it and see if the results are acceptable to you, that is all that matters. A lot of the discussion about required dpi for a certain print size is just academic. If you get results you are happy with then it is all good. The printer drivers on the other expect to see a certain dpi for a given print size, if they do not get that given to them they will resize the image using a technique that is far from optimal and may not give the desired results.
      > > >
      > > > Alan
      > > >
      > > > --- In ccd-newastro@yahoogroups.com, "GordonM" <gmandell@> wrote:
      > > > >
      > > > > Hello,
      > > > >
      > > > > I was reading that an appropriate resolution (ppi) depends on the size of the print and the viewing distance from the print. Viewing distance was defined as the print's diagonal dimension x 1.5. The ppi needed was defined as 3438 divided by the diagonal dimension (in inches). For example, an 8"x10" print viewed at 19" would require a ppi of 179.
      > > > >
      > > > > Here is a link to the reference:
      > > > >
      > > > > http://tinyurl.com/25pppec
      > > > >
      > > > > What do you think?
      > > > >
      > > > > Thank you.
      > > > >
      > > > > Gordon
      > > > >
      > > > > --- In ccd-newastro@yahoogroups.com, "kafuensis" <astrophotonut@> wrote:
      > > > > >
      > > > > >
      > > > > > Actually the image should be resampled to what the printer driver wants to see. Some printer drivers have poor sampling routines. I print a lot of "fine art" prints, so I have a lot of experience with it. You should calibrate your monitor and printer, if you are using an external printing service you need to make sure that you use their printer profiles. Yes you can see what the print will look like in photoshop by doing a "soft proof". There are lots of tutorials on the web. You will need the profile for the printer and paper you are going to use and then do a soft proof. If your monitor is well calibrated you should be able to get a good idea which colors will be out of gamut for the printer and how it will look. This is all under the larger topic of "color management". There is lots of info, a good tutorial for going from image to print is on the Luminous Landscape site, they have just updated their video tutorial and the final version of the new version will be available soon. It is very detailed.
      > > > > >
      > > > > > Alan
      > > > > > --- In ccd-newastro@yahoogroups.com, "GordonM" <gmandell@> wrote:
      > > > > > >
      > > > > > > Hello,
      > > > > > >
      > > > > > > I am seeking some general advise about printing astrophotographs.
      > > > > > >
      > > > > > > What is the minimal resolution in ppi (250 was recommended to me)? Other than a large mosaic, this limits my photos to a relatively small size unless I resample. Is resampling to create more pixels an acceptable alternative to mosaics?
      > > > > > >
      > > > > > > Recent prints I ordered are darker than I had expected (compared to the same image on the computer screen). Is there procedure in Photoshop to "see" what the image would look like on a printed medium in terms of brightness and color?
      > > > > > >
      > > > > > > Thanks in advance.
      > > > > > >
      > > > > > > Gordon
      > > > > > >
      > > > > >
      > > > >
      > > >
      > >
      >
    • phils67
      I discovered that commercial printers (Costco, Walmart) are very inconsistent in their print density. Sometimes images were printed too dark while other times
      Message 2 of 25 , Oct 16, 2011
      • 0 Attachment
        I discovered that commercial printers (Costco, Walmart) are very inconsistent in their print density. Sometimes images were printed too dark while other times they were too light. Aa image that was printed perfectly the first time was way too dark when I reprinted it. None of my astro images is a perfect "fit" to the commercial printer's 4x6 image size so I decided to make good use of the extra space on the print. Anything I print is pasted into a 4x6 template that contains a 20 step grey scale that was manually generated.

        When I pick up prints; I check the grey scale. If the print is too light or dark; it's obvious. Notify the clerk and they'll usually reprint it while you wait. The same thing can be done with color swatches. Combine this with the published printer profile and you shouldn't ever have a bad print.

        Phil


        --- In ccd-newastro@yahoogroups.com, "GordonM" <gmandell@...> wrote:
        >
        > Hello,
        >
        > I am seeking some general advise about printing astrophotographs.
        >
        > What is the minimal resolution in ppi (250 was recommended to me)? Other than a large mosaic, this limits my photos to a relatively small size unless I resample. Is resampling to create more pixels an acceptable alternative to mosaics?
        >
        > Recent prints I ordered are darker than I had expected (compared to the same image on the computer screen). Is there procedure in Photoshop to "see" what the image would look like on a printed medium in terms of brightness and color?
        >
        > Thanks in advance.
        >
        > Gordon
        >
      Your message has been successfully submitted and would be delivered to recipients shortly.