One luminance value replaces all three color channels
For every pixel, the calculated Y value is written into red, green and blue, removing hue while preserving relative brightness.
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Convert an image to grayscale and save it as PNG, JPEG, or WebP.
Convert an image to grayscale using a luminance-weighted RGB formula, then save the result as PNG, JPEG or WebP without changing its pixel dimensions.
Color information is discarded by this operation and cannot be reconstructed from the grayscale output. Keep the original file separately.
For every pixel, the calculated Y value is written into red, green and blue, removing hue while preserving relative brightness.
The alpha channel itself is not changed. PNG or WebP can therefore retain transparency better than JPEG.
If your source relies on transparent areas, choosing JPEG changes that capability even though the grayscale math itself leaves alpha untouched.
The output canvas uses the same width and height as the loaded source image.