Extract Palette

Extract Palette decodes your image onto a canvas, walks it at a fixed stride collecting pixels that are at least half opaque, and groups those samples into the number of colours you asked for. An image under roughly 48,000 pixels is read in full; above that the stride grows in whole pixels, which lands the sample somewhere between 24,000 and 48,000 of them. Each group comes back as HEX, RGB and HSL, alongside its share of the pixels that were read and the closest match from a short built-in list of names.

There are two ways of doing the grouping and they answer different questions. Median cut splits the colour space into boxes along each box's widest axis, choosing what to split next by both spread and population, so a small area of strong colour survives more often than it does under the alternative; every sampled pixel ends up in some box, so those shares add up to the whole. Most used slices each channel into fixed blocks of sixteen values and ranks the blocks by how many samples fall in them, which favours what dominates — but two shades one step apart still separate when a block boundary runs between them, and anything outside the top few blocks is dropped, so its percentages do not total 100. Median cut also cuts at an obvious gap when it finds one rather than always at the median, which stops two clearly separate colours being averaged into a third that appears nowhere.

Three things are worth knowing before you trust a swatch. Every colour returned is the mean of a cluster, so a HEX code may not correspond to any single pixel in the photo — for the literal value of one point use Image Color Picker, and for the single strongest colour use Dominant Color. The percentages are measured over the pixels that were sampled, and with the neutral filter on they are measured over whatever survived it, not over the whole frame. And the stride counts pixels in reading order rather than stepping across rows and columns, so when the width divides into it neatly — 4000 × 3000 gives a stride of 500, 6000 × 4000 a stride of 1000 — the samples land on as few as six or eight vertical lines, and a narrow upright feature between them is never seen at all. Decoding, sampling and grouping all run in this browser tab, so the image is not uploaded, and once the page has loaded the work carries on with the network off.

The results panel shows the swatches with their hex codes, a table, and the three files below it. No palette is kept between runs: a result is not stored, not set against a previous one, and not reorderable by hand, and there is no way to pin a colour you like and re-run for the rest.

Runs on your device. Your file is processed directly in this browser.