mask

Isolate a PNG's dark/shadow pixels into their own transparent-masked image, by luminance threshold.

Mask a PNG down to only the pixels within a chosen hue, saturation, and lightness range.

Isolate a PNG's light/bright pixels into their own transparent-masked image, by luminance threshold.

Mask a PNG down to only the pixels near any of several target colors, within an adjustable tolerance.

Turn a PNG's alpha channel into a grayscale visualization: white is opaque, black is transparent.

Mask a PNG down to only the pixels matching its single most frequent exact color.

Mask a PNG down to only the pixels whose exact color appears nowhere else in the image.