Overview
Compares two images pixel by pixel, such as before/after or standard/variant versions. In addition to a difference image, it outputs the number and percentage of changed pixels, error, and change bounds, supporting both visual inspection and automated QA.
Usage tips
- Connect the reference image to
aand the comparison target tob. Areas where the image dimensions differ are compared against transparent pixels. - Use
threshold = 0for exact equality, or a small positive value to ignore compression artifacts and tiny rounding errors. boundsis a Map withx,y,width, andheight. Width and height are 0 when there are no changes.
Common pitfalls
Turn compare_alpha OFF when only transparency differs and you want to compare RGB
alone. With it OFF, stored RGB differences are ignored when both pixels are fully
transparent because they cannot affect the visible result. The difference image is not
automatically amplified for visibility, so use the numeric outputs as well for very
small differences.
Related nodes
tile_preview: visually inspect tile seamsbatch_render: create an image list for multiple variants