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Choosing Better-Quality JPEG Images With Software?

Posted by timothy on from the on-the-tip-of-my-script dept.

kpoole55 writes "I've been googling for an answer to a question and I'm not making much progress. The problem is image collections, and finding the better of near-duplicate images. There are many programs, free and costly, CLI or GUI oriented, for finding visually similar images — but I'm looking for a next step in the process. It's known that saving the same source image in JPEG format at different quality levels produces different images, the one at the lower quality having more JPEG artifacts. I've been trying to find a method to compare two visually similar JPEG images and select the one with the fewest JPEG artifacts (or the one with the most JPEG artifacts, either will serve.) I also suspect that this is going to be one of those 'Well, of course, how else would you do it? It's so simple.' moments."

4 of 291 comments (clear)

  1. Translation: Please help me with my porn... by Chyeld · · Score: 5, Insightful

    Dear Slashdot,

    Recently I checked my porn drive and realized that I have over 50 gigibytes of jpg quality porn collected. Unfortunately, I've noticed that a good portion of these are all the same picture of Natlie Portman eating hot grits. Could you please point me to a free program that will allow me to find the highest resolution, best quality version of this picture from my collection and delete the rest?

    Many Thanks!

  2. It's easy by Anonymous Coward · · Score: 5, Insightful

    Run the DCT and check how much it's been quantized. The higher the greatest common factor, the more it has been compressed.

    Alternatively, check the raw data file size.

  3. Re:AI problem? by Spy+der+Mann · · Score: 4, Insightful

    Here's a simple but expensive formula:

    1. Get the image
    2. Compress it severely.
    3. Compare the difference between original and the compressed.

    The lower the difference, the lower the image quality.
    4. Profit!

    Or you could just measure the amount of data in the DCT space. Duh.

  4. Re:File size by timeOday · · Score: 5, Insightful
    This is the kind of problem you can solve in 2 minutes with 95% accuracy (by using file size), or never finish at all by listening to all the pedants on slashdot. When people know a little too much they love to go on about stuff like entropy and information gain, just because they (sort of) can.

    Try file size on the set of images of interest to you and see if it coincides with your intuition. If it does, you're done.