3 Replies Latest reply on Aug 18, 2006 5:58 AM by Newsgroup_User

    image resoltion question

    bwr
      I have a basic question about image resolution. I have taken some pics for a brochure with a digital camera. The pictures are 2800 x 2100 pix. (6.1 MP), 72 DPI.

      My printer recommends sending TIFF format at 300 DPI. I can create a postcard at 300 DPI and add the image, without resampling the image.

      Will that print ok, or do I need to find a digital camera that will shoot at 300 DPI. I am obviously a novice and I could not find an answer to my question in the archives.

      Thanks.
        • 1. Re: image resoltion question
          Level 7
          On Thu 17 Aug 2006 02:56:42p, bwr wrote in macromedia.fireworks:

          > I have a basic question about image resolution. I have taken some
          > pics for a brochure with a digital camera. The pictures are 2800 x
          > 2100 pix. (6.1 MP), 72 DPI.
          >
          > My printer recommends sending TIFF format at 300 DPI. I can create a
          > postcard at 300 DPI and add the image, without resampling the image.
          >
          > Will that print ok, or do I need to find a digital camera that will
          > shoot at 300 DPI. I am obviously a novice and I could not find an
          > answer to my question in the archives.

          I don't have a postcard handy to measure, but they run somewhere around 3.5
          x 5 inches to 4 x 6 inches. At 300 pixels per inch, 4 x 6 inches works out
          to 1200 x 1800 pixels. So you have adequate resolution for what you're
          doing, and even to crop a bit.

          FW, by the way, is the wrong tool for print. Use Freehand, Photoshop, or
          another image editing app; your printer can, I'm sure, tell you what format
          they like to get files in.
          • 2. Re: image resoltion question
            Level 7
            On Thu, 17 Aug 2006, bwr wrote

            >I have a basic question about image resolution. I have taken some pics for a
            >brochure with a digital camera. The pictures are 2800 x 2100 pix.
            > (6.1 MP), 72
            >DPI.

            Digital cameras have no meaningful concept of dpi. The dpi value you may
            get with a digital camera image is purely for printing the image at a
            particular size.
            I have a jpg taken with a rather elderly Sony. Irfanview[1] Image
            Information has, very sensibly, blank fields for the image dpi. Paint
            Shop Pro says the dpi is 192 pixels/inch and is taken from the jpg Exif
            data.
            I've just got a new Sony W50 and, again, Irfanview says there is no dpi
            while PSP says 72 dpi from Exif data.

            So what is correct. Nothing, or 192 dpi , or 72 dpi?
            None of the above. Software/devices try to be helpful and set a dpi
            value for you. Often this is the ubiquitous, and totally irrelevant, 72
            dpi because they think you might like to print the image at a particular
            size, but that's all it is - a suggestion.

            > My printer recommends sending TIFF format at 300 DPI. I can create a
            >postcard
            >at 300 DPI and add the image, without resampling the image.
            > Will that print ok, or do I need to find a digital camera that will shoot at
            >300 DPI.

            There is no such thing as a camera that shoots at a particular dpi.
            dpi is for printing and you set it to whatever you want in the program
            you use to print images. Resampling is only required when you want to
            change the pixel dimensions.

            [1] www.irfanview.com
            It's quite instructive to use Irfanview to change the dpi value in an
            image to zero, and then see how different graphics programs handle it.

            --
            Richard Mason
            http://www.emdpi.com
            • 3. Re: image resoltion question
              Level 7
              On Thu, 17 Aug 2006 22:56:42 +0400, bwr <webforumsuser@macromedia.com>
              wrote:

              > I have a basic question about image resolution. I have taken some pics
              > for a
              > brochure with a digital camera. The pictures are 2800 x 2100 pix. (6.1
              > MP), 72
              > DPI.

              As a small addition to what Richard said, I think I'll explain in more
              detail while camera ppi (or dpi) is a fake.

              From practical point of view, neither camera nor your eye have resolution
              in "inches". Both your eye and your camera have *angular* resolution, not
              *linear*. It may be recalculated to linear only when you are referring to
              particular viewing distance - that is, from a long distance you only
              recongize objects of meter size, and from a hand distance - of millimeter
              size; and they may take the same amount of pixels in your camera photos.

              As a result, there is no such a thing like "best resolution for print" -
              you may print large billboard at much smaller resolution than fine art
              catalog, and both will look the same under appropriate circumstances - one
              from several meters distance, the other being viewed through a looking
              glass. Also, there is no such a thing as "camera resolution" (unless we
              put the real ruler in the scene <g>). There may be *formal* resolution
              setting the camera puts in the image file, or even more likely some formal
              resolution assumption your software makes when it reads the file without
              any resolution setting in it (you know, software don't like "divide by
              zero" things, so it often makes some non-zero assumptions when it can't
              get real figures).

              So forget about resolution of camera files. All you need is enough pixels
              to cover the number of inches that you wish, under the print resolution
              you want. As Joe said, you are likely to have more than you need.

              --
              Ilya Razmanov
              http://photoshop.msk.ru - Photoshop plug-in filters