A fast pixel-level image comparison library, originally created to compare screenshots in tests. Now with additional support of PIL.Image instances Python port of https://github.com/mapbox/pixelmatch.
Features accurate anti-aliased pixels detection and perceptual color difference metrics.
from pixelmatch import pixelmatch
num_diff_pixels = pixelmatch(img1, img2, 800, 600, diff, threshold=0.1)
Implements ideas from the following papers:
- Measuring perceived color difference using YIQ NTSC transmission color space in mobile applications (2010, Yuriy Kotsarenko, Fernando Ramos)
- Anti-aliased pixel and intensity slope detector (2009, Vytautas Vyšniauskas)
python -m pip install pixelmatch
from PIL import Image
from pixelmatch.contrib.PIL import pixelmatch
img_a = Image.open("a.png")
img_b = Image.open("b.png")
img_diff = Image.new("RGBA", img_a.size)
# note how there is no need to specify dimensions
mismatch = pixelmatch(img_a, img_b, img_diff, includeAA=True)
img_diff.save("diff.png")
from pixelmatch import pixelmatch
width, height = 1920, 1080
img_a = [R1, G1, B1, A1, R2, B2, G2, A2, ...]
img_b = [R1, G1, B1, A1, R2, B2, G2, A2, ...]
data_diff = [0] * len(img_a)
mismatch = pixelmatch(img_a, img_b, width, height, data_diff, includeAA=True)
pixelmatch(img1, img2, width, height, output, threshold, includeAA, alpha, aa_color, diff_color, diff_mask, fail_fast)
img1
,img2
— RGBA Image data of the images to compare. Note: image dimensions must be equal.width
,height
— Width and height of the images.output
— Image data to write the diff to, orNone
if don't need a diff image. Note that all three images need to have the same dimensions.threshold
— Matching threshold, ranges from0
to1
. Smaller values make the comparison more sensitive.0.1
by default.includeAA
— Iftrue
, disables detecting and ignoring anti-aliased pixels.false
by default.alpha
— Blending factor of unchanged pixels in the diff output. Ranges from0
for pure white to1
for original brightness.0.1
by default.aa_color
— The color of anti-aliased pixels in the diff output in[R, G, B]
format.[255, 255, 0]
by default.diff_color
— The color of differing pixels in the diff output in[R, G, B]
format.[255, 0, 0]
by default.diff_mask
— Draw the diff over a transparent background (a mask), rather than over the original image. Will not draw anti-aliased pixels (if detected).fail_fast
- If true, will return after first different pixel.
Compares two images, writes the output diff and returns the number of mismatched pixels.
Compares two images, writes the output diff and returns the number of mismatched pixels. Exact same API as pixelmatch.pixelmatch
except for the important fact that it takes instances of PIL.Image for image parameters (img1
, img2
, and output
) and the width/size need not be specified.
expected | actual | diff |
---|---|---|
- feat: add fail_fast option #144
- type: fix typing issues
- chore: test Python 3.10
- feat: make package comply with PEP-561
- typing: use
Sequence
instead ofList
forRGBTuple
- build: switch to
poetry_core
#81
- feat: add function to compare PIL.Image instances through contrib.PIL.pixelmatch #42
- BREAKING CHANGE: remove
options
parameter #38 - docs: use absolute url for images in README
- fix: fix bug in fast path #18
- Initial release