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NYTimes.com Article: Basics: A Shutterbug’s Guide to Meting Out the Megapixels

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  • ar109@netscape.net
    This article from NYTimes.com has been sent to you by ar109@netscape.net. Everything you wanted to know about pixels ar109@netscape.net /--------------------
    Message 1 of 2 , Oct 30, 2003
      This article from NYTimes.com
      has been sent to you by ar109@....

      Everything you wanted to know about pixels


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      Basics: A Shutterbug’s Guide to Meting Out the Megapixels

      October 30, 2003

      THE more megapixels the merrier - or so you'd gather from
      digital camera prices. The higher the number of megapixels,
      the more expensive the camera will be in comparison with
      others with similar features. But what are megapixels? How
      many do you need? Is more always better?

      Pixels (known as megapixels when you count them by the
      million) are picture elements, the tiny spots of data that
      make up a digital image. All photos are made up of tiny
      elements: from the ink dots in newspaper photos to the
      grains of silver or particles of color dye in film
      photography. A good photo usually has millions of these
      elements. The more there are, the sharper and more detailed
      the picture is, and the harder it is to distinguish the
      elements from one another.

      A digital camera's effective pixel count is its horizontal
      resolution multiplied by its vertical resolution. An image
      2,048 pixels across and 1,536 high has just over 3.1
      megapixels; a 2,560 x 1,920 image is just over 4.9

      Digital cameras made for amateurs usually have between two
      and five megapixels, though cameras with eight megapixels
      or more will be available soon.

      Those numbers are no match for 35-millimeter film, which
      has a resolution equivalent to 20 or 30 megapixels, but
      digital cameras can nonetheless produce excellent images.

      How many megapixels you will need depends on how you plan
      to use your pictures. For e-mail, an image size of 640 by
      480 pixels (0.3 megapixel) is usually best: large enough to
      look sharp on a computer screen but small enough to upload
      or download quickly. For prints, more resolution is
      required, and the bigger the print, the greater the
      difference the pixel count makes.

      For prints measuring up to 8 by 10 inches, the difference
      between shots with two megapixels and five megapixels can
      be hard to discern. This was not always true, but current
      digital cameras do a better job of processing the raw data
      from their image sensors into image files on their memory
      cards. ("Most people will never, ever need something above
      three megapixels," said Jon Sienkiewicz, the vice president
      for marketing at Minolta. "I'll make 8-by-10's all day long
      from that.")

      Cropping and Zooming

      In prints larger than 8 by 10 inches, differences in pixel
      counts become more noticeable. Few amateurs make prints
      that big, but another reason to go for a higher pixel count
      is the ability to crop. Pictures that looked good when you
      shot them may contain distracting elements; cropping allows
      you to prune those elements away and make the picture
      stronger. Crop out 40 percent of your picture, though, and
      you lose 40 percent of its pixels. That might be a
      worthwhile tradeoff if it reduces a five-megapixel image to
      three megapixels, but not so if the image goes from two
      megapixels to a paltry 1.2.

      It is also possible to crop within the camera, zeroing in
      on an important subject area so that it fills as much of
      the frame as you want. A zoom lens does this by narrowing
      its view to exclude some subject areas while magnifying
      whatever is left within the frame. The picture area
      contains just as many pixels as before, but with more of
      them now devoted to the subject area you want, its details
      are clearer. Don't confuse this process, optical zoom, with
      so-called digital zoom, a purely electronic process that
      selects a small subject area by throwing away the
      surrounding pixels: the pixel count of the area you select
      with digital zoom is the same as before, so you don't gain
      anything but a tighter composition, and the picture may
      look fuzzier. It's like cropping your picture in your
      computer, only with less time to select your composition
      and no chance to change your cropping if you don't like the

      "It's not as valuable for cameras that have zoom lenses as
      it is for entry-level cameras that don't," said Chuck
      Westfall, director of technical information for camera
      products at Canon, referring to digital zoom. Entry-level
      cameras are also, alas, likely to have lower pixel counts
      to start with. On the other hand, such cameras are mainly
      used for snapshots, "and for snapshot-sized photos,
      sometimes digital zoom isn't too bad," said Sally Smith
      Clemens, a product manager at Olympus.

      Whether you crop in your computer or with your camera's
      digital zoom, the quality of your results will depend on
      how many pixels your camera used to make the image and how
      much of that image you crop away.

      Memory and Formats

      The downside of pixel-rich pictures is the way they fill a
      camera's memory. Most cameras come with a skimpy
      16-megabyte memory card, enough to hold a handful of
      two-megapixel images but perhaps only one five-megapixel
      image. A larger memory card is a good investment, but it
      can be costly: Depending on the type, a 64-megabyte card
      can cost $20 to $40, a 128-megabyte card costs $30 to $60,
      and a 256-megabyte card costs $50 to $150.

      Large images can fill even a big memory card quickly - for
      example, a 128-megabyte card might hold as few as eight
      five-megapixel images. For that reason, cameras give you a
      choice of resolution settings, letting you use a
      five-megapixel camera's full resolution for important
      shots, but throttle it back to three or two megapixels for
      snapshots. The camera's display will then tell you how many
      shots will fit on the remaining memory.

      Digital cameras offer a choice of file formats; your choice
      affects the number and quality of images a card can hold.
      Just about all digital cameras can save images as JPEG (or
      JPG) files, which compress the image data to save memory
      space but lose some picture quality in the process. (The
      format is named after the Joint Photographic Experts Group,
      which devised it.) Both the memory savings and quality loss
      vary depending on the amount of compression, so most
      cameras offer a choice of compression levels, typically
      described as small, medium and large, or fine, standard and
      economy. A 16-megabyte memory card, for example, might hold
      9 three-megapixel images in Fine mode, 17 in Standard and
      32 in Economy.

      Saving an image as a JPEG file has surprisingly little
      effect on its sharpness and detail. But once a JPEG image
      has been modified by cropping, resizing, sharpening,
      lightening, darkening or altering its color balance, it
      should not be saved as a JPEG again. Doing so would
      compress the file further, and data and picture details
      would be discarded. Instead of using the Save command, use
      Save As, and store the picture in an uncompressed format,
      like TIFF (Tagged Image File Format), which preserves all
      remaining details.

      Many cameras allow you save images as TIFF files as you
      shoot. These give you maximum image quality but take up a
      lot of space (about 14 megabytes for a five-megapixel image
      in TIFF form, versus about 2 megabytes or less for a JPEG)
      and take longer to store on the memory card (a problem if
      you're shooting action).

      Some cameras also offer a RAW format, which contains all
      the details the image sensor picked up, unaffected by the
      camera's settings for white balance, exposure compensation
      and other factors. These files require a bit more work but
      give you more creative control over the result. For
      example, in JPEG's, "overexposed highlights are just lost,"
      Mr. Westfall of Canon said. "In RAW, you have a bit of
      wiggle room in those areas, and even more capability for
      bringing out detail in the shadow areas." Unlike TIFF, RAW
      is a nonstandard file format, differing from one make of
      camera to another. To edit RAW files, you may need the
      editing software supplied with the camera, or plug-ins for
      programs like Adobe Photoshop.

      Experts suggest buying a camera with the highest megapixel
      count you can afford, and saving your photos as JPEG files
      unless you plan to edit them. That will cut the time your
      camera spends storing one image before shooting the next,
      and will leave room for more shots on its memory card. A
      high megapixel count and compressed files will help ensure
      that you'll be ready when you see something worth shooting.
      If you start to run out of memory before you run out of
      picture opportunities, using fewer pixels or a coarser JPEG
      setting will let you slip a few more pictures in. Better to
      get the shot but lose a little quality than to miss the
      shot entirely.

      "It's not about pixels alone," said Ms. Clemens of Olympus.
      "It's about pictures."



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    • E.Rodier
      Anyone who received an advertising booklet from a credit card company this week might like to check out the name brand digital cameras available in the
      Message 2 of 2 , Oct 30, 2003
        Anyone who received an advertising booklet from a credit card company this
        week might like to check out the name brand digital cameras available in the
        Membership Rewards program.

        The challenge for family history projects is to plan a picture the "right"
        size for a wall chart or family book. Discovered that my sample chart with
        medical clip art had some 3000x3000 pixel images, much larger than usual
        size when face pictures of people are only 240 pixels high. -- Elizabeth

        ----- Original Message -----
        Subject: NYTimes.com Article: Basics: A Shutterbug’s Guide to Meting
        Out the Megapixels

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