imgcompare

This little tool compares two images using pillow's ImageChops and then converts the differnce to black/white and sums up all found differences by summing up the histogram values of the difference pixels.

Taking the difference between a black and a white image of the same size as base a percentage value is calculated.

Check the tests to see example diffs for different scenarios. Don't expect the diff of two jpg images be the same for the same images converted to png. Don't do interformat compares (e.g. JPG with PNG).

Dependencies

Pillow ( )https://python-pillow.org/ )

Usage

compare images

same = is_equal("image_a.jpg", "image_b.jpg")

use the tolerance parameter to allow a certain diff pass as same

same = is_equal("image_a.jpg", "image_b.jpg", tolerance=2.5)

get the diff percentage

percentage = image_diff_percent("image_a.jpg", "image_b.jpg")

or work directly with pillow image instances (also works for is_equal)

image_a = Image.open("image_a.jpg")
image_b = Image.open("image_b.jpg")
percentage = image_diff_percent(image_a, image_b)

Examples

Slight Difference

Image A <img width=150" border="1" src="./tests/testimages/cat.jpg">

Image B <img width=150" border="1" src="./tests/testimages/cat_slight_diff.jpg">

imagecompare.image_diff_percent(JPG_CAT, JPG_CAT_SLIGHT_DIFF)

result => 0.344547385621

Difference between jpg and same jpg encoded again

Image B is Image A, but run again through the JPEG encoder, so Image B now has slightly more compression artefacts than Image A, which results in a small diff.

Image A <img width=150" border="1" src="./tests/testimages/cat.jpg">

Image B <img width=150" border="1" src="./tests/testimages/cat_jpg_reencoded.jpg">

imagecompare.image_diff_percent(JPG_CAT, JPG_CAT_REENCODED)

result => 0.0149232026144

Black and White

Image A <img width=150" border="1" src="./tests/testimages/black.jpg">

Image B <img width=150" border="1" src="./tests/testimages/white.jpg">

imagecompare.image_diff_percent(JPG_BLACK, JPG_WHITE)

result => 100.0

Black and Half-Black-White

Image A <img width=150" border="1" src="./tests/testimages/black.jpg">

Image B <img width=150" border="1" src="./tests/testimages/half_black_white.jpg">

imagecompare.image_diff_percent(JPG_BLACK, JPG_HALF_BW)

result => 50.0

License

MIT License

GiriprakashR / imgcompare