3 Replies Latest reply on Mar 17, 2009 1:02 PM by (bryan_coleman)

    Question about RAW to JPG file sizes

      Hello all, I have a question/concern in reference to file size changes when converting from RAW to JPG formats in PSE6. I've recently purchased a CANON 50D, and have started shooting in RAW format (actually RAW2+JPG). I have the CAMERA RAW 5.2 plugin and my workflow process is something akin to this:
      1. Separate all RAW and JPG images into their respective folders.
      2. Open the RAW folder in BRIDGE, and then open up a CR2 file. CR2 file is approx 15MB at this point, as reported in Finder.
      3. Perform various corrections in ACR52 to the file, then do as SAVE AS to a DNG file.
      4. Next step is to OPEN IMAGE, bringing it up in PSE6.
      5. Make any necessary corrections to the picture, and then do a SAVE AS to a new file name and folder, selecting JPG format.
      6. Selection MAX QUALITY from subsequent dialogue box, and SAVE.

      When the file is saved, its now down to a mere 2.1 or 2.2MB, and when viewing its properties (vs. the same file that came from camera in JPG format), its down from a 44x66" format, to somewhere around 4x6" and 240dpi.

      I've been doing some reading on this over the weekend, but cant explain away the severe loss in file size, and whether this is right, or if I'm doing something wrong in the process.

      Appreciate any advice or suggestions to help improve my work processes, and ultimately the final photos!
        • 1. Re: Question about RAW to JPG file sizes
          michael shaffer Level 1
          Bryan ... Your description of the size of the saved JPG relative to the original is not clear. For comparing JPG files sizes relative to the quality setting, you need also take the number of pixels into account. If the saved JPG has 4x6x240=5750 pixels, what is the number of pixels for the orignal? If I guess 12M, or twice as many, that still doesn't make up for the loss in size -- my guess is that the camera is saving a lossless JPG, when PSE saves only lossy JPGs.

          hth :)
          • 2. Re: Question about RAW to JPG file sizes
            Dennis 1111 Level 2
            Regarding your file size questions, have a look at this thread and see if it answers some of your questions:

            http://www.fredmiranda.com/forum/topic/741532/0

            > When the file is saved, its now down to a mere 2.1 or 2.2MB, and when viewing its properties (vs. the same file that came from camera in JPG format), its down from a 44x66" format, to somewhere around 4x6" and 240dpi.

            Dimensions and resolution are related and multiple combinations can be produced from the same number of pixels. For example, your 50D at maximum image size produces 4,752 by 3,168 pixels. This full-size image could be printed at:
            - 19.8 x 13.2 inches at 240 PPI
            - 47.52 x 31.68 inches at 100 PPI
            - 7.92 x 5.28 inches at 600 PPI

            As you can maybe see, talking about dimensions and resolution doesn't make much sense until you are ready to consider printing. Note also that I used "PPI" or Pixels Per Inch since this is the slightly more correct terminology. DPI or "Dots Per Inch" is usually a reference to how a printer lays down the ink drops onto the paper. Many printers actually put more "dots" on the paper than there are pixels. Many people and companies use DPI when they mean PPI.

            Now in your case you are apparently starting with an SRAW2 raw file. SRAW2 files from the 50D have a reduced number of pixels and are 2,276 pixels wide by 1,584 pixels high. At 240 PPI this would allow you to print the image at 9.9 by 6.6 inches. If you are ending up with something smaller than that, it means you have either re-sampled the image (changed the image so the same image is displayed with fewer pixels) or you have cropped the image.

            Hope that helps.
            • 3. Re: Question about RAW to JPG file sizes
              Level 1
              Michael, Dennis,
              Thanks to both of your for your insightful replies. I went back last night and rechecked several things, and figured out what my misconceptions were.
              Now I start to see where all these various factors interact, and what changes and what stays the same when going from one format to the other.
              Ciao
              Bryan