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  • The "Compression Artefacts" issue

    I had some photos rejected on appeal and the screener also suggested that they should have been rejected for compression artefacts too. The screener also suggested that I should "save in a higher quality".

    But I always save in the highest quality available. This rejection reason is coming up increasingly and I would like to put a lid on it.

    When I have done all the bits and bobs - sharpening, cropping, etc etc and then reducing to the acceptable size, I then save the photo under a file name; I am then asked to pick the image quality and I always pick "maximum".

    Is there anything further I should be doing that I am not doing during the preparation process, that would avoid compression artefacts. I have asked (and I know others have asked) this question before, but the reason given last time was different.

  • #2
    Could you please select a few rejections so that we can see better and try to understand where the compression comes from ? Thanks

    Alex

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    • #3
      Here you go: originally rejected for CMOS Dust spots, so this is the only rejection shown, but (apparently) should also have been rejected for compression:

      http://www.jetphotos.net/viewreject_b.php?id=5290365

      http://www.jetphotos.net/viewreject_b.php?id=5290343

      http://www.jetphotos.net/viewreject_b.php?id=5290353

      http://www.jetphotos.net/viewreject_b.php?id=5290356

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      • #4
        I see fuzzy lines and compressed background on all these photos, caused by JPG compression.
        My photos on Flickr www.flickr.com/photos/geridominguez

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        • #5
          Originally posted by LX-A343 View Post
          I see fuzzy lines and compressed background on all these photos, caused by JPG compression.
          Agree with Gerardo.

          If you are already saving at the highest quality, there are some other possible causes:
          the original is a lower quality (low resolution) to begin with
          you cropped too much on long distance shots
          something in the postprocessing, like sharepening before resizing, check this thread: http://forums.jetphotos.net/showthre...ected-for-soft

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          • #6
            Originally posted by pdeboer View Post
            Agree with Gerardo.

            If you are already saving at the highest quality, there are some other possible causes:
            the original is a lower quality (low resolution) to begin with
            you cropped too much on long distance shots
            something in the postprocessing, like sharepening before resizing, check this thread: http://forums.jetphotos.net/showthre...ected-for-soft
            ... or adding to that list:
            - You save at low Image quality in your camera
            - you save multiple times (always do your editing and save only once, at the very end of your post processing
            - in your software "high quality" does not mean "no compression", but just the best out of different settings to save for the internet, but does nevertheless have some compression.

            ... or a mix of some of the mentioned problems.
            My photos on Flickr www.flickr.com/photos/geridominguez

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            • #7
              Thanks everyone ... I think the answer lies in sharpening before re-sizing. I will avoid this in future. I only ever save once, so I don't think that's an issue.

              Anyway, many thanks to you all for replying. Good lessons to learn!

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              • #8
                Originally posted by akerosid View Post
                Thanks everyone ... I think the answer lies in sharpening before re-sizing. I will avoid this in future. I only ever save once, so I don't think that's an issue.

                Anyway, many thanks to you all for replying. Good lessons to learn!
                That doesn't have any impact at all on JPG compression!! That's why we dodn't mention it in our list of possible reasons.
                My photos on Flickr www.flickr.com/photos/geridominguez

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                • #9
                  Originally posted by pdeboer View Post
                  Agree with Gerardo.

                  If you are already saving at the highest quality, there are some other possible causes:
                  the original is a lower quality (low resolution) to begin with
                  you cropped too much on long distance shots
                  something in the postprocessing, like sharepening before resizing, check this thread: http://forums.jetphotos.net/showthre...ected-for-soft
                  You didn't, but it was mentioned - here (Pamela's last point!) ... that's what I have been doing.

                  Incidentally, I what is the ideal resolution (for a Nikon user) to select. I've always tried to select the finest resolution available (although I never use Raw).

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                  • #10
                    Believe me, sharpening before or after resizing does have nil impact on JPG compression. It only results in more or less fine jagged lines, but compression is something different. Do an easy check: if your photos at the size you use to upload here are below 200kb, something is fishy.
                    My photos on Flickr www.flickr.com/photos/geridominguez

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                    • #11
                      Did you use noise reduction software?

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                      • #12
                        Originally posted by akerosid View Post
                        You didn't, but it was mentioned - here (Pamela's last point!) ... that's what I have been doing.

                        Incidentally, I what is the ideal resolution (for a Nikon user) to select. I've always tried to select the finest resolution available (although I never use Raw).
                        RAW without a doubt. It is totally lossless and gives you the maximum resolution whereas .jpg will always have a degree of lost detail compression. Combined with a photoshop saving at the maximum 12 and compression should not be a problem.
                        If it 'ain't broken........ Don't try to mend it !

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                        • #13
                          You really do not need to shoot RAW to get acceptable pics for jp. If the camera is set to use the highest quality jpg setting, there is way enough room for editing. The EXIF shows no wrong camera setting, so I would say either noise filter used (which makes no sense at ISO160) or maybe saved more than once after opening the original file.

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