• Add first-class TypeScript types to the project. They'll be maintained in the repo from now on. #139
• Improve matching performance by ~22%. #150

• Potentially breaking: improve handling of semitransparent pixels. Previously, they were blended with white, so a transparent pixel vs white pixel would show zero difference; now pixels are blended with an irregular pattern, making it easier to catch regressions. (h/t @NathanMOlson #142)
• Improve match performance by ~6%. #147
• Significantly improve diff generation performance. (h/t @kawanet #105)
• Fix options handling to use the default value when undefined is passed explicitly. (h/t @denis-sokolov #146)
• Fix ESLint failing on Windows when working on the library locally. (h/t @haraldreingruber-dedalus #123)

⚠️ Breaking: publish pixelmatch as a ES module. Use the older v5.3.0 if you need to support CommonJS environments.

Upgrade pngjs dependency (used in the pixelmatch CLI) from v4 to v6.

• Added a diffColorAlt option for coloring pixels that got darker differently (for differentiating between "added" and "removed" parts). #87 (h/t @tristen)
• Dropped Node v4/v6 support in the binary.

Added diffMask option. #73 (h/t @tmeasday)

• Fix input validation failing in some Jest environments. #62

• 🐞 Fix alpha option being ignored in case of identical images.
• Slightly more robust input validation.

• ⚠️ Breaking: update to ES6 syntax, dropping Node <6.4 and IE11 support.
• 🎨 Added configurable diff output (options alpha, aaColor, diffColor) (@dreignier @VP-)
• ⚡️ Improve matching performance by ~35%.
• ⚡️ Bypass detailed comparison when image data is identical, significantly improving performance when running tests on CI #60 (thanks to @bontscho).
• Fix anti-aliasing detection on image edges #51 (@IvanSanchez).
• Produce a meaningful error when image data is in the wrong format #53 (thanks to @LearningNerd)
• CLI: return non-zero exit code when images differ #54 (@maio).
• CLI: make diff output optional.
• Make the published NPM module smaller.

Fixed the command-line to properly handle the case when threshold is not provided.

• Updated dependencies (including pngjs to remove npm install warning).
• Fixed a bug where the command line could sometimes fail.

• Breaking: switched to a much more accurate color difference metric based on recent research. As a side effect, the threshold scale changed — bump your old value by about ~70%.
• Changed processing of alpha-channel (blending to white instead of black when comparing images)
• Added an option to skip diff image creation (by passing null as the output argument)

• Breaking: changed the API to accept options object literal (with threshold and includeAA properties) rather than arguments.
• Breaking: changed threshold to be relative to YUV distance (not squared); this means you'll have to change the threshold values you're currently using to sqrt(threshold).
• Added usage examples for Node & browsers in the readme.

Increased accuracy of anti-aliased pixels comparison.

Adds Node 0.10 support for command line and tests.

• Much more accurate anti-aliased pixels detection algorithm #2
• Display transparent pixels as white rather than gray in diff

Note a breaking API change: antialiasing argument (number, 1 by default) is replaced with includeAA (boolean, false by default). Anti-aliasing detection is still enabled by default but always happens with 1 pixel radius.

Fixed minor bug in color difference calculation.

Use premultiplied Y'UV colorspace for color comparison, making it more in line with human perception of color.