Bug#849395: diffoscope: Improve support for comparing images

[Emanuel Bronshtein]

Source: diffoscope
Severity: wishlist

Dear Maintainer,

1. compare image metadata (EXIF / XMP / size / etc..) for various images formats, can be done with following tools:
	exiftool - http://www.sno.phy.queensu.ca/~phil/exiftool/ - https://packages.debian.org/sid/libimage-exiftool-perl
	exiv2 - http://www.exiv2.org/ - https://packages.debian.org/unstable/exiv2
	ImageMagick identify - https://www.imagemagick.org/script/identify.php - https://packages.debian.org/sid/imagemagick (by using -verbose option)
	
2. visual compare images in HTML output
	images can be shown using data URI: https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
	The below tools can be used to detect difference in images:
		Resemble.js - https://github.com/Huddle/Resemble.js/
		PerceptualDiff - https://packages.debian.org/sid/perceptualdiff
		ImageMagick - https://www.imagemagick.org/Usage/compare/ - https://packages.debian.org/sid/imagemagick
		image-diff - https://github.com/uber/image-diff