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Thread: QuantSmooth: JPEG quality option

  1. #1

    Default QuantSmooth: JPEG quality option

    Version 4.56:
    - New JPG option: Use QuantSmooth loading (PlugIn, thanks to Ilya Kurdyukov)

    An option must be added that enables the given option regarding file quality.
    For example only for files below JPEG quality<60

    Otherwise, you constantly have to open the settings to enable and disable this checkbox - when the file is of poor quality and when it is good.
    Whereas, it can be done automatically ;-)
    Last edited by zubzero; 22.10.2020 at 01:42 AM.

  2. #2

    Default

    Hi, I'm the author of JpegQS.

    1) There is no such thing as JPEG quality after the image has been encoded in JPEG.
    2) JpegQS tries to compensate for the chroma reduction, usually many JPEG images are saved at half the color resolution. So images with rich colors will benefit from it anyway (even with 90% quality).

    You can keep it on if you have mid-end/hi-end hardware and are not running on battery power. Better not to use if you are viewing large, full-size images from your camera - you won't see much benefit from it.

  3. #3

    Default

    If desired, Irfanview can show the quality values applied on the encoder (image - information)
    Conversion 420 to 444 for >Q60 takes place and often requires a more accurate analysis ("magnifying glass") in order to see the differences (eg photo)
    The purpose of this request is to correct only artifacts that are clearly visible to the eye - thereby reducing the load on the computer on files with a deliberately acceptable quality.

    You also mentioned large format images.
    As an add-on, it would be nice to have the ability to disable JpegQS for more than FullHD and/or 4K

    These two limitations, together, can help weak PCs in some cases. Namely, when the processing of files lasts for several minutes with the "freezing effect" of the program.

    p.s. User simply forgot to turn off JpegQS and opens 8K Photo with Q90 quality ... ctrl-alt-del
    Last edited by zubzero; 24.10.2020 at 03:32 AM.

  4. #4

    Default

    Well, this plugin is not the something everyone needs, most people rarely notice JPEG artifacts. There are situations when this becomes useful - zooming images, reusing images saved in JPEG format (and there is no lossless source to find), or printing (usually artifacts become more visible on paper). And the visibility of JPEG artifacts depends more on the specific content rather than the quality. For example, black text on a white background or a drawing generated on a computer. Think of it as an additional tool for a Swiss knife that can help in certain situations.

    I think the option that is needed is to not use this for very large images, i.e. usually full-scale camera photos, so the size can be specified in megapixels. For the smaller images - delay is mostly unnoticeable.

    In fact, this plugin needs some feedback on whether it is useful for enough people. If yes, then we can discuss what can be done to make it more convenient for them to use it. If no one will use it, then there is no point on improving it.

  5. #5
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    Default

    Quote Originally Posted by Ilya Kurdyukov View Post
    In fact, this plugin needs some feedback on whether it is useful for enough people. If yes, then we can discuss what can be done to make it more convenient for them to use it. If no one will use it, then there is no point on improving it.
    Well you have my vote. I didn't know this kind of method existed. I had some animation jpgs where the artifacts along the facial lines were really bad. I actually thought one day I would clean them up by hand (easy since faces are one color), but this looks really great instead (combined with Resample for zooming). Very neat.

    Loads fast for animation shots (i.e. computer drawings as you said), but slow for photos (which it probably doesn't help), so you wouldn't want it on by default, but it's a little hassle to turn it on in Settings and reload the image. It would be nice if there was menu or hotkey for it, so you could easily toggle it and see the difference.

    Thanks for this feature!

  6. #6
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    Why not add it to the Effects menu instead of having an option in JPG settings?

    It would just need to reopen the file and process it with the plugin.

  7. #7

    Default

    Quote Originally Posted by Bhikkhu Pesala View Post
    Why not add it to the Effects menu instead of having an option in JPG settings?
    Because this is not an effect like filtering that can be applied to RGB pixels, but as an additional step in the JPEG decoding process. Thus, you cannot combine it with any other changes made to the image - this must be the first.

    Quote Originally Posted by Bhikkhu Pesala View Post
    It would just need to reopen the file and process it with the plugin.
    Yes, but that would go beyond the usual logic of what the effect is, because this is a JPEG decoding option.

  8. #8
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    Quote Originally Posted by Ilya Kurdyukov View Post
    Because this is not an effect like filtering that can be applied to RGB pixels, but as an additional step in the JPEG decoding process. Thus, you cannot combine it with any other changes made to the image - this must be the first.
    I think it could work similarly like "JPEG lossless transformations" work.
    IrfanView 4.56 64bit, Windows 10 20H2

  9. #9

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    Quote Originally Posted by JendaLinda View Post
    I think it could work similarly like "JPEG lossless transformations" work.
    Well, yes. The original JpegQS command line tool is based on the jpegtran tool from libjpeg, which performs these transformations. It behaves like a JPEG transform.

    Thus, you can rewrite the JPEG file using this transform. But there is no point in rewriting the original file, because after this conversion, the JPEG image size will become few times larger. This transform tries to recreate the precision of the DCT coefficients that was lost when the JPEG encoder applied a quantization matrix (which depends on the selected quality percentage). It's better as an image viewer plugin.

  10. #10
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    That's true. Overwriting the original file is a bad idea.

    I thought the menu command could reload the JPEG file with some kind of flag enabling the QuantSmooth filter. That means Irfan would have to make a special code for it.
    IrfanView 4.56 64bit, Windows 10 20H2

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