Free Color Isolator
Click a colour in your reference and see everywhere else that mix appears, within a colour difference you set; keep up to six labelled isolations at once and export each as a mask. Or keep one hue family in colour and send the rest to grey to judge its weight in the composition. Exports PNG. Free, with no sign-up, and your picture never leaves your device.
Drop an image here, or paste from clipboard
Your image stays on your device. Nothing is uploaded.
JPG, PNG, WebP, GIF, AVIF or BMP
Where else is this mix?Click a colour to keep every area within a CIEDE2000 tolerance of it in colour, averaged over 5 × 5 pixels.
Six labelled isolations.Each with its own name, tolerance and share of the picture; show them in their own colours or in label colours.
Mask PNG.Export any isolation as a full-size black and white mask, soft at the tolerance edge, ready to use as a selection.
Hue band.Keep one hue family in colour by angle, with eight presets, a tolerance of 5° to 90° and a coverage verdict.
- Free
- No sign-up
- Runs in your browser: your image never leaves your device
What is a color isolator?
A color isolator is an image filter that keeps chosen colors in full color and turns everything else gray, so a painter sees where a color lives and how much of the picture it covers. This one matches a sampled color by CIEDE2000 difference, or keeps a whole hue family by angle, which is selective color by hue.
How to use the Color Isolator
The tool takes 6 steps, all on your device.
Drop in your reference photo (it never leaves your device) or try a sample.
Click a colour in the picture, or focus the picture, move with the arrow keys and press Enter. Everything within its tolerance stays in colour; the rest drops to grey.
Widen or narrow each isolation's tolerance, name it (the shadow mix, the sky blue), and add more, up to six. Each pixel belongs to the nearest isolation within its tolerance.
Switch Matches to Label colours to see which areas belong to which isolation, and read each one's share of the picture.
Download an isolation's mask PNG to use as a selection, or export the view as a PNG.
For whole hue families rather than one mix, switch Isolate by to Hue band and pick a hue and a tolerance in degrees.
What the Color Isolator does
The Color Isolator selects by colour difference and not hue alone, lets the nearest isolation win, and labels in colours anyone tells apart.
The whole colour compared
A hue window cannot tell a dark red shadow from a pale pink of the same hue. Colour match compares the full colour, lightness, chroma and hue together, by CIEDE2000, the colour difference formula paint and print industries use; a difference of about 1 is roughly the smallest most people notice side by side. Its job among the color tools for artists is answering 'where else in this reference is this exact mix?'.
Fast on big photos
The picture's distinct colours are indexed once, in a background worker, and each difference is computed per colour rather than per pixel, so moving a tolerance slider updates the view without re-reading the image.
Nearest isolation wins
When a pixel is within the tolerance of two isolations, it belongs to the one it is closer to, so shares never overlap and add up to at most 100%. The view fades matches over the last quarter of the tolerance so edges do not flicker.
Label colours anyone can tell apart
Label colours come from the Okabe–Ito set, chosen to stay distinguishable with the common forms of colour-blindness.
Hue band with a verdict
In Hue band mode, hue is read on the HSV circle (red 0°, green 120°, blue 240°), near-neutral pixels under 12% saturation never count, the window fades over 12° past the tolerance, and coverage gets a verdict: under 2% a small accent, under 15% a clear minority, under 45% a major player, above that dominant.
Private, full-size export
Everything runs in your browser and your photo is never uploaded. Previews work on up to 1,600 pixels on the long edge; Export PNG and the masks are computed again on the full-resolution photo.
For painters who plan color by families
Beginners, working painters, illustrators and art teachers plan a picture's color by families.
Beginners
Click the red sphere on the Still life sample and see how its colour runs into shadow at a wider tolerance.
Working painters
Sample a mix you have already made and find every other passage it can serve before you mix anything new.
Illustrators
Export masks of two or three key colours to use as selections when adjusting a digital piece.
Art teachers
Show a class, with label colours, how few distinct mixes a strong reference really needs.
Where else is this mix?
Painters mix a puddle and then ask where else this mix belongs. A photograph hides that answer: the same colour under slightly different light reads as different, and a nearby colour reads as the same. Clicking a colour and seeing every area within a set difference of it turns the question into a map. At a narrow tolerance you see the passages one puddle can paint as it is; at a wider one, the areas it can reach with a small adjustment.
Several isolations at once show how a reference divides into mixes. Name them after the puddles on your palette, and the shares tell you how much of each to mix: on the Still life sample, the lit side of the red sphere at a tolerance of 14 covers 5% of the picture.
Reading the isolated image
Look first at the shape of what survives, not its size: one connected mass reads as deliberate, while the same share sprayed across the frame reads as noise. Label colours make several isolations readable at once, and Gray keeps every other pixel at its own value, so you can see whether a colour mass sits on a value mass.
An intended accent, the red scarf or the orange umbrella, should claim only a small share of the surface. If its isolation spreads across a third of the frame, it is no longer an accent. Neighbours also change how an isolated colour reads; the simultaneous contrast lab shows by how much.
Choosing a tolerance
Start narrow, around 3 to 6, to find the same mix; widen toward 10 to 15 to gather the passages a small change of the puddle would cover. In Hue band mode, tolerance is an angle instead: narrow (5–15°) finds one tube colour, wide (40–90°) a whole warm or cool family. For the warm and cool balance of the whole frame at once, the color temperature and saturation map sorts every pixel into warm, cool or neutral.
From isolation to mixing plan
Isolate the major mixes in turn and note their shares. The largest is your base puddle; mixes under a few percent are accents, mixed in small amounts and guarded. Then run your own painting, photographed in even light: if an accent's share has crept above the reference, you know which passages to calm.
Once a colour is located, its chroma is the next question. The hue value chroma separator shows where chroma peaks inside the territory you found here.
Further reading
The page below goes further into the ideas the Color Isolator works with, and opens on the site named beside it.
- Color families and harmony for painters (ArtisticMasterclass.com)
Tips from a working artist
From Sujith Puthran, artist and founder: what I actually do at the easel.
Sample the middle of an area, not its edge; the sample averages 5 × 5 pixels.
A mix that shows up under 2% of the picture is an accent: protect it by keeping everything around it quieter.
Name each isolation after its puddle; the names travel into the mask files.
If an isolation grabs the shadow side too, narrow its tolerance before adding a separate shadow sample.
Check your own painting against the reference's isolations; drift in the shares is the clearest sign a colour has been overused.
Use Label colours to see at a glance which mix covers which area when isolations sit side by side.
Why your picture stays on your device
The Color Isolate is a program your browser downloads and runs by itself. When you choose a picture, the browser reads it from your files and does the work on your own phone or computer; no copy is sent to this site or to anyone else, and what you export is saved straight from the browser. That is why there is nothing to upload and nothing to sign up for. The privacy page says what the site does collect.
Questions about the Color Isolator
The 6 questions below cover tolerance, several colours and the share figure, then mask files, export size and privacy.
Using it
What does the tolerance number mean?
In colour match the tolerance number means a CIEDE2000 colour difference. A difference of about 1 is roughly the smallest most people notice side by side, and each area within the number you set of the sampled colour counts as a match. In Hue band mode it is the angle either side of the chosen hue.
Can I isolate several colours at once?
Yes, you can isolate several colours at once: up to 6 in colour match, each with its own tolerance. A pixel within reach of two goes to the nearer one, and each isolation shows its share of the picture.
How is the share counted?
It is the share of the picture's opaque pixels whose colour is within the isolation's tolerance, measured on the preview. Below 1% it shows one decimal place.
Files and privacy
What is in a mask PNG?
A mask PNG holds a full-size black and white image: white where the isolation matches, fading to black over the last quarter of its tolerance, black everywhere else. Most image editors can load it as a selection or layer mask.
Does the exported PNG keep my photo's full size?
Yes, the exported PNG keeps your photo's full size.
Does the Color Isolator upload my photo?
No, the Color Isolator does not upload your photo. The isolation runs entirely in your browser on your device; nothing is sent to a server.
Drop in a reference, click a colour and see where else it lives before you mix the next puddle.
Free · No sign-up · Runs in your browser