How can I do these image processing tasks using OpenGL ES 2.0 shaders?

I just added filters to my open source GPUImage framework that perform three of the four processing tasks you describe (swirling, sketch filtering, and converting to an oil painting). While I don’t yet have colorspace transforms as filters, I do have the ability to apply a matrix to transform colors. As examples of these filters … Read more

Comparing two histograms

Comparing histograms is quite a subject in itself. You’ve got two big classes of comparison functions : bin-to-bin comparison and cross-bin comparison. Bin-to-bin comparison : As you stated, standard sum of differences is quite bad. There’s an improvement: the Chi-squared distance. If H1.red[0] = 0.001 and H2.red[0] = 0.011, then H2.red[0] is much more important … Read more

Is it possible to tell the quality level of a JPEG?

You can view compress level using the identify tool in ImageMagick. Download and installation instructions can be found at the official website. After you install it, run the following command from the command line: identify -format ‘%Q’ yourimage.jpg This will return a value from 0 (low quality, small filesize) to 100 (high quality, large filesize). … Read more

What is “semantic segmentation” compared to “segmentation” and “scene labeling”?

“segmentation” is a partition of an image into several “coherent” parts, but without any attempt at understanding what these parts represent. One of the most famous works (but definitely not the first) is Shi and Malik “Normalized Cuts and Image Segmentation” PAMI 2000. These works attempt to define “coherence” in terms of low-level cues such … Read more

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