Channel distortions - image processing basics

Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
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Channel distortions - image processing basics

Post by Parzival » 2018-08-11T00:51:07-07:00

I am a begginer in image processing, and a begginer with the library imagemagick. While I do have some experience, I wanted to ask what is channel distortion in image processing.
taken from the imagemagick website, in the "compare" command section:

In addition to the visual interpretation of the difference in an image and its reconstruction, we report a mathematical measure of the difference:

-> magick compare -verbose -metric mae rose.jpg reconstruct.jpg difference.png
Image: rose.jpg
Channel distortion: MAE
red: 2282.91 (0.034835)
green: 1853.99 (0.0282901)
blue: 2008.67 (0.0306503)
all: 1536.39 (0.0234439)

I don't understand what is the red, green, blue and 'all' distprtion represent. Can someone explain it to me ?

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Re: Channel distortions - image processing basics

Post by snibgo » 2018-08-11T05:04:43-07:00

"Distortion" is another word for "difference". The number in parentheses eg (0.034835) tells us how much difference there is: 0.0 means no difference, 1.0 means totally different.

"-metric MAE" (see ... php#metric) calculates the mean of the absolute differences of pixel values. It calculates this for individual RGB channels, and for all the channels together.
snibgo's IM pages:

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