Is there freeware that can objectively score the quality of a JPEG or RAW photo?

Asked 6/15/2012

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I'm looking for software, preferably free, that can analyze a photo file (JPEG or RAW) and give it some kind of quality score so I can compare images from different cameras without having to zoom in and inspect each one manually. Is there any reliable way to do this, or any objective metric that can compare image quality automatically?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

14y ago

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I don't think there is any software that does what you say exactly in the way that you want it. But if you can relax your requirements a little there is something that may work for you.

Instead of just looking at a single image and giving it a score, let's say you have a golden image, one that you have inspected in every way and you consider it the best it can be for its class.

Now you can compare other images of the same subject (with same focal length, same exposure, etc.) and get a score for how close the new images are to the golden one. For example, you could use this technique to objectively measure how much the JPEG compression degraded an image, using the equivalent raw image as your golden image. (note that I said objective, this algorithm does not take into account subjective aspects of a comparison, so it isn't sometimes an indication of perceived quality).

The algorithm is called Peak signal-to-noise ratio or PSNR in short. There are several open source implementations of this algorithm. OpenCV and FFmpeg have them, this question at stackoverflow.com lists a few more.

Originally by user7604. Source · Licensed CC BY-SA 4.0

user7604

14y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

There isn’t really a reliable freeware tool that can look at any JPEG or RAW and produce a single meaningful “quality score.” Image quality depends on many things—focus, sharpness, noise, compression artifacts, exposure, color, and also subjective preferences—so histogram and ISO alone are not enough.

What is possible is comparison against a known reference image. If you have a “golden” image of the same subject under the same conditions, some methods can score how close another image is to that reference. That can work for specific tests, such as measuring JPEG compression loss relative to a RAW version.

A simple file-size or bitrate-style formula is only a rough indicator and won’t tell you whether an image is actually sharp, well focused, or visually better.

For practical evaluation, free tools like GIMP or Darktable are better suited to inspecting images and rating them yourself. Darktable also includes rating features to help organize comparisons.

UniqueBot

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14y ago

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