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Thread: Recent advancement in image resolution enhancement

  1. #1

    Recent advancement in image resolution enhancement

    I read this article a little while ago and thought some may be interested in advancements in digital image enhancement technology that (fingers crossed) may become available/applicable for photographers down the road. The context of their objectives is somewhat dissimilar to the typical photographers, yet it seems there is much overlap in the overall goal: better post-processing methods for enhancing image resolution.

    https://arxiv.org/abs/1612.07919

  2. #2
    8x10, 5x7, 4x5, et al Leigh's Avatar
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    Re: Recent advancement in image resolution enhancement

    It all depends on what you mean by "enhancing image resolution".
    You can increase the pixel density so larger prints look "normal" rather than pixelated.

    But there's no valid way to add fine detail that's not in the original digital image.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  3. #3
    Jac@stafford.net's Avatar
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    Re: Recent advancement in image resolution enhancement

    Quote Originally Posted by Patrick Gauthier View Post
    I read this article a little while ago and thought some may be interested in advancements in digital image enhancement technology that (fingers crossed) may become available/applicable for photographers down the road. The context of their objectives is somewhat dissimilar to the typical photographers, yet it seems there is much overlap in the overall goal: better post-processing methods for enhancing image resolution.

    https://arxiv.org/abs/1612.07919
    Cruise more academic literature and look for common proposals. The abstract posted is rather empty, but most abstracts are click-bait for scholars and hackers. In the end they are selling something, you know.

  4. #4

    Re: Recent advancement in image resolution enhancement

    You can try it out for yourself! However, their code downsizes your image to make low-res examples (i.e., to see if their method can produce something similar to the original (ground truth). If you're savvy in python maybe you can try on full-res images.

    https://github.com/shakeh3r/Enhancenet

  5. #5

    Re: Recent advancement in image resolution enhancement

    Quote Originally Posted by Leigh View Post
    It all depends on what you mean by "enhancing image resolution".
    You can increase the pixel density so larger prints look "normal" rather than pixelated.

    But there's no valid way to add fine detail that's not in the original digital image.

    - Leigh
    I would say it all depends on what you mean by "valid" The rest is rather objectively defined in the article.

  6. #6

    Re: Recent advancement in image resolution enhancement

    No offense intended to anyone. I know some software developers hype their wares far too much.

    I once worked with a guy who believed a PS plug-in developer claiming that a six pixel image of a small bird could be made to look reasonably like that bird via use of their plug-in. Apparently, many people bought into it.

    After taking a closer look, I have to admit their results are better than I expected. Still, what is not there cannot be put back with any automated process.
    Last edited by consummate_fritterer; 13-Feb-2018 at 02:38.

  7. #7

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    Re: Recent advancement in image resolution enhancement

    Quote Originally Posted by Leigh View Post
    It all depends on what you mean by "enhancing image resolution".
    You can increase the pixel density so larger prints look "normal" rather than pixelated.

    But there's no valid way to add fine detail that's not in the original digital image.

    - Leigh
    +1

    The article is interesting, but the comparison of the grasshopper images says it all. Basically, their test is to down-res an image and see if their algorithm can up-res it to match the original (the ground-truth image). As they explain, their method tends to add things that were not there in the original, and loses things that were (as do other methods). To me, that is not a valid (true) outcome, even though their method does work better than the others.

  8. #8

    Re: Recent advancement in image resolution enhancement

    Quote Originally Posted by mmerig View Post
    +1

    The article is interesting, but the comparison of the grasshopper images says it all. Basically, their test is to down-res an image and see if their algorithm can up-res it to match the original (the ground-truth image). As they explain, their method tends to add things that were not there in the original, and loses things that were (as do other methods). To me, that is not a valid (true) outcome, even though their method does work better than the others.
    The results are comical, but when you see the file they had to work with its pretty impressive. Figure 7 shoes some issues with the texturing smooth features adjacent to patterned features that are problematic.

    Still, it's pretty amazing how they can generate novel information that renders an otherwise blur startlingly similar to the ground-truth image. I'm very curious what it will do to an already somewhat acceptable image (for example a botched focus 4x5 negative that could still be acceptable for an 8x10 print) in terms of increasing potential/acceptable print size. My thinking is that while the image examples they provide in the paper as a whole leave much to be desired, perhaps for very large images (i.e. LF scans) the egregious artifacts in their final product would be less noticeable.

    I'm going to try with a scan of an out of focus negative to see what happens. Will post results here.

  9. #9

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    Re: Recent advancement in image resolution enhancement

    Your test would be more practical for most photographers compared to theirs. Who would down-sample an image and then try to reconstruct it using a complex algorithm, instead of just using the original, better image? The bicubic smoothing for down-sampling may give a different set of errors than a low-resolution image obtained in practice (low pixel count, blurry from motion, out of focus, etc.) But bicubic smoothing provided a consistent, well-understood starting point for their tests of course.

    Although their method can give better-looking images, it fails from a forensic standpoint without ancillary information (e.g., Figure 7). It's basically pearls on a pig. A lot of the utility of their method depends on whether the objective is a more truthful image or something that just looks better somehow.

    Regarding your test with an out-of-focus image, it would be better to also have a well-focused image, that is the same in every other way, to compare the improved out-of focus one to. Also, a scan of an analog enlargement of a section of the in-focus photo rather than an an initial zoomed-in scan would minimize the degradation during digital conversion of the true image. The same could be done for the out-of focus image. The file sizes and computation time would be smaller too.

    Despite my negativity about the algorithm, I look forward to your comparisons, and thanks for letting us know about their work and what you plan on doing.

  10. #10
    Nodda Duma's Avatar
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    Re: Recent advancement in image resolution enhancement

    If you consider the "downsampling operator" is analogous to the optical point spread function and the Nyquist frequency for the imaging system, then you'll understand why this technique and others like it are not only theoretically possible, but practically possible as well.

    This isn't the only approach nor are they working in a vacuum. Super-resolution techniques have been actively employed for over a decade, seeing first widespread use in smart phone cameras.

    So yeah, it is a reality. Their research, like almost all research, is a small slice of ongoing incremental advancement in a field which the public conscious is only dimly aware of. So I have to chuckle at naysaying that sounds akin to explaining why this internet thing will never take off.

    If you think this is amazing technology, look at actual hot optical engineering research topics such as computational optics or plastic GRIN lens printing, graphene detector research, or laminated infrared optics.
    Newly made large format dry plates available! Look:
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    .. because my wife is happy when I can cover my photography expenses!

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