How do I enhance low quality JPEG images?

  1. Is there any way to enhance low quality and low resolution JPEG images? Is there a program I can use or something?

    I have dozens of grainy and poor quality JPEGs that I would like to sharpen up, but I do not own photoshop.
     
  2. jcsd
  3. Greg Bernhardt

    Staff: Admin

    Enhancing low quality photos is tough because you need some algorithm to add in data to the image that didn't exist. Photoshop does have some advanced tools for this. Free options do exist but I'm not sure how much they will help. Certainly sharpen filters are common though.

    Try http://www.getpaint.net
     
  4. FactChecker

    FactChecker 817
    Science Advisor
    Gold Member

    To sharpen a picture, look at the "unsharp mask" plugin for paint.net. It's name is deceptive. It actually sharpens edges. It must be used judiciously because it is easy to overdo the effect. Done well, it is can be really improve a dull photo. You can actually see some of that effect in many professional photos and HDTV screen images.
     
  5. jtbell

    Staff: Mentor

    Unfortunately, unsharp mask tends to increase the "graininess" of an image, i.e. "noise" in areas that are supposed to have a smooth texture. It works best for enhancing soft edges and making them look sharper.
     
  6. Andre knew of a good, free online photo editing program that had an excellent noise reduction filter. "Graininess" often means too much noise. Maybe he'll see this thread.
     
  7. FactChecker

    FactChecker 817
    Science Advisor
    Gold Member

    Good point. The OP mentions both low resolution and wanting to "sharpen" them. I would recommend that he find a friend with Photoshop and test a photo to see what will work. Then he can look for those capabilities in free software. I have seen photos where fractal techniques were used to add artificial detail that looked very realistic.
     
  8. Attached Files:

  9. Alternatively ''wavelet denoise'' plugin on GIMP , [GIMP and plugins are free] ...
     

    Attached Files:

  10. Borek

    Staff: Mentor

    Just remember - the image may look better, but as Greg said in the very first answer - it won't have more information than there was in the compressed image. Changes will be only cosmetic, to appease the eye.

    Actually in a way they will make the image worse - while it will look better, it will contain other artifacts, not as visible, but still degrading the information stored. You may try to take a picture of a newspaper with different sizes of text (ads, titles, plain text), and then to see which parts of the text can be still read after saving the image with different levels of compression and after applying different filters. My bet is that each additional operation will make the newspaper more difficult to read.
     
  11. If the brief is to sharpen blurred-text see "SmartDeblur" ...

    Before
    [​IMG]

    After
    [​IMG]
    Now readable, but with plenty of artifacts.
     
    Last edited: Sep 4, 2014
  12. Borek

    Staff: Mentor

    Interesting and impressive, but that's not exactly the same thing. If the blur is added in a "systematic" way the information is still in the picture - and it is possible to attempt to recover it. When the image was compressed with the lossy compression situation is different.
     
  13. It’s me who should say about this. Not exactly as Borek claims because of rounding errors, but blurring an image in computer’s memory, especially if lossy compression is not applied, inflicts much less data loss than blurring due to physical effects in realistic conditions (such as out of the focus photograph).
     
  14. FactChecker

    FactChecker 817
    Science Advisor
    Gold Member

    A lot of what makes a photograph look sharp is not the amount of information. I think that HDTV looks good even on a very large screen at a size to which I would hesitate to blow up a photograph. If you figure the photograph pixel count that HDTV is equivalent to, it is less than most cameras. Of course an extremely small pixel count will be hard to fix.
     
  15. Borek

    Staff: Mentor

    Sure - but first, OP never stated what he wants (just an appeasing effect, or getting more information from the picture), second, my bet is OP is not aware of the distinction (so he can be wasting his time trying to do something that is impossible).
     
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