How to detect subjective image quality

Question

For an image-upload tool I want to detect the (subjective) quality of an image automatically, resulting in a rating of the quality.

I have the following idea to real

Answer 1

Assesing the image (the same goes for sound or video) quality is not an easy task, and there are numerous publications tackling the problem.

Much depends on the nature of the image - different set of criteria is appropriate for artificially created images (i.e. diagrams) or natural images (i.e. photographs). There are subtle effects that have to be taken into consideration - like color masking, luminance masking, contrast perception. For some images a given compression ratio is perfectly adequate, while for other it will result in significant loss of quality.

Here is a free-access publication giving a brief introduction to the subject of image quality evaluation.

The method you mentioned - compressing the image and comparing the result with the original is far from perfect. What will be the metric that you plan to use? MSE? MSE per block? For sure it is not too difficult to implement, but the results will be difficult to interpret (consider images with high-frequency components and without them).

And if you want to delve more into the are of image quality assessment there is also a lot of research done by the machine learning community.