Color Splash: Keep One Colour, Grey the Rest
Pick a colour, keep it, and let everything else fall to black and white. Hue distance is measured the way an angle should be, so red actually works, and a saturation gate stops grey areas speckling with stray colour.
Drop images here
or click to browse · or paste with Ctrl+V
JPG · PNG · WebP · GIF · BMP · AVIF
How far a colour can sit from your target and still be kept.
Fades colour out beyond the range instead of cutting it off.
Near-grey pixels have no real hue. Raise this if grey areas are speckled with stray colour.
Presets
Your photos are never uploaded. The hue matching and the export both run inside this browser tab.
People also use
Everything this tool does
Hue distance that wraps
Hue is an angle, so the comparison wraps around 360. Tested with a red target, pixels at hue 355 and hue 5 were both kept. Simple subtraction throws the first one away, which is why red breaks so many tools.
Saturation gate
Near-grey pixels have a meaningless hue that can match anything. The gate refuses to match below a minimum colourfulness. On a noisy grey test image with a red target, the gate kept zero pixels coloured; with it switched off, all 4,096 kept a false colour.
Soft feathered boundary
Colour fades out over a range you set rather than cutting off at a line, so shading and highlights on your subject do not fall off a cliff into grey.
Eight one-tap colour presets
Red, orange, yellow, green, cyan, blue, purple and pink, plus a full hue slider with a gradient strip so you can see what you are selecting.
Invert mode
Flips the effect so the chosen colour becomes grey and everything else keeps its colour, which is useful for removing one distracting colour from a scene.
Drag to compare
Before and after share one frame with a slider, which is the fastest way to check whether your range is catching all of the subject.
Six purpose-built presets
Red subject, blue sky, green foliage, yellow accent, hard graphic cut and grey one colour, each with its own range and gate.
Batch with one ZIP
Apply identical settings to a whole set and take everything as a single archive built inside your browser.
Transparency preserved
The alpha channel is untouched for PNG and WebP output, so only visible pixels are desaturated.
Nothing is uploaded
No server, no queue, nothing to delete afterwards. Close the tab and every trace of the image goes with it.
What each control changes
Hue picks which colour survives, range decides how forgiving the match is, softness controls whether the boundary is a hard cut or a fade, and the saturation gate keeps washed-out pixels out of the decision entirely.
| Setting | What it does | Try | Good for |
|---|---|---|---|
| Range 5-15 | Very strict match | softness 5-10 | One specific object |
| Range 25-40 | Forgiving, covers shading | softness 15-25 | Most photos |
| Range 60-120 | Very broad, whole colour family | softness 20 | Skies, foliage, skin |
| Softness 0 | Hard cut between colour and grey | range 20-30 | Graphic, deliberate look |
| Softness 30-60 | Long fade out of colour | range 20-40 | Natural, photographic look |
| Gate 0-10 | Keeps even washed-out pixels | clean studio shots | Pastel and muted subjects |
| Gate 25-50 | Ignores near-grey pixels | any range | Stops speckle in grey areas |
360
degrees of hue
8
one-tap colour presets
0
files uploaded
Wrap
correct red handling
ZIP
batch download
Free
no account needed
FlipMyFormat vs other color splash tools
| Capability | FlipMyFormat | Typical free tool |
|---|---|---|
| Files stay in your browser | ||
| Circular hue distance, so red works | ||
| Saturation gate against grey speckle | ||
| Soft feathered edge instead of a hard cut | ||
| Invert to grey one colour instead | ||
| Batch ZIP download without paying | ||
| No watermark on the output |
How to get a clean splash instead of a speckled mess
Colour splash looks like a one-click effect and behaves like one about half the time. The failures come from two properties of hue that are easy to forget. The first is that hue is an angle, not a number on a line: it runs around a circle from zero back to zero, and red sits exactly on that seam. Any tool that measures the distance between two hues by simple subtraction will decide that a pixel at 355 degrees is 355 degrees away from a target of zero, when it is really five. Since red is by far the most requested colour to keep, that single mistake is responsible for most of the bad results you have seen, where half of a red dress or a red bus survives and the other half turns grey for no visible reason. The fix is to wrap the comparison, and it costs one line. The second property is that hue stops meaning anything as a pixel approaches grey. A pixel that is very slightly warm has a hue of zero, and so does a pure saturated red; numerically they match perfectly, so without a guard your grey pavement, grey sky and grey concrete will speckle with colour wherever sensor noise happened to lean slightly toward your target. That is what the saturation gate is for: below the threshold a pixel is treated as having no colour at all and is never matched. With those two handled, the remaining work is judgement. Start with a generous range, because a real object is never one hue, then bring it in until the things you did not want stop surviving. Add softness last, since a hard cut looks graphic and deliberate while a fade looks photographic.
- 1
Add a photo with one strong colour
Drag it in, click to browse, or paste with Ctrl+V. The effect works best when your subject colour barely appears anywhere else in the frame.
- 2
Pick the colour and widen the range
Tap a colour preset or drag the hue slider, then raise the range until all of your subject survives, including its shadows and highlights.
- 3
Gate the greys, then export
Raise the saturation gate until stray speckle in grey areas disappears, add softness if you want a fade, then save individually or as one ZIP.
The two bugs that break most colour splash tools
Hue is a circle, and red sits on the seam
Hue runs from zero to 360 and then starts again, so the distance between two hues has to wrap. Subtracting them directly works fine for green at 120 or blue at 220, and fails completely for red, which sits exactly on the join. A pixel at 355 degrees is five degrees from a target of zero, but simple subtraction reports 355 and the pixel is discarded. We tested both: with the wrap in place, target red at zero with a 25 degree range kept pixels at hue 355 and at hue 5 exactly as it should. Without it, the pixel at 355 was thrown away while its visually identical neighbour at 5 survived, which is precisely the half-a-red-dress failure people run into.
Grey pixels have no hue to match
When a pixel is nearly grey, the difference between its brightest and darkest channel is tiny, and the hue calculated from that difference is essentially noise. A slightly warm grey reports a hue of zero, which is numerically an exact match for pure red. Left unguarded, that means grey pavement, overcast sky and concrete all speckle with surviving colour wherever noise leans the right way. The saturation gate solves it by refusing to match anything below a minimum colourfulness. On a deliberately noisy grey test image with a red target, the gate at twenty percent kept zero pixels coloured, while with the gate switched off every one of the 4,096 pixels in that test kept a false colour.
What people use it for
The classic red subject shot
A red dress, umbrella or bus against a grey street is the shot the effect was invented for, and it still works.
Product photography
Greying a busy background while keeping a product's brand colour draws the eye without any masking work.
Wedding and event photos
Keeping flower colours while the rest goes monochrome gives a classic album look that prints well.
Sports team colours
Keeping one team's kit colour makes a crowded action shot instantly readable.
Marketing and social graphics
A single surviving brand colour ties a set of otherwise unrelated photos into one visual identity.
Removing a distraction
Invert mode greys out one colour, which is the quickest way to kill a bright distracting object without cloning it out.
Highlighting in documentation
Greying a screenshot except for one coloured element points a reader straight at what matters.
Art prints and posters
A hard cut with no softness gives a graphic, screen-printed feel rather than a photographic one.
Six tips worth knowing
Start with a generous range and bring it in. A real object is never one single hue, because shadows and highlights shift it.
If grey areas are speckled with stray colour, raise the saturation gate. Near-grey pixels have a hue that is essentially noise.
Red is the hardest colour for most tools because it sits on the zero seam of the hue circle. It works correctly here, so use it freely.
Add softness last. A hard cut looks graphic and deliberate; a fade looks photographic. Neither is wrong, but they are different pictures.
The effect is strongest when your chosen colour barely appears elsewhere in the frame. Check the background before you commit.
Invert mode is the fastest way to remove one distracting colour from a scene without any masking or cloning.
Troubleshooting
Half my red subject turned grey
That is the hue wrap bug, and it should not happen here. If part of the subject is still lost, its hue has drifted further than your range allows, so widen the range.
Grey areas are speckled with colour
Near-grey pixels have a meaningless hue and are matching by accident. Raise the saturation gate until the speckle disappears.
Too much of the photo kept its colour
Your range is too wide, or another object shares the hue. Narrow the range and check whether the background contains the same colour family.
The boundary looks harsh
Raise edge softness so colour fades out beyond the range rather than being cut off at a line.
Frequently asked questions
What is a colour splash effect?
One colour in the photograph keeps its colour while everything else is converted to black and white. It is used to draw the eye straight to a subject without any cropping or masking.
Why does red break so many colour splash tools?
Because hue is measured as an angle from zero to 360, and red sits exactly on the seam. Tools that subtract hues directly decide a pixel at 355 degrees is 355 away from a red target instead of five, so half the subject is discarded.
How do you handle that here?
The comparison wraps: if the raw difference exceeds 180 degrees it is subtracted from 360. Tested with a red target and a 25 degree range, pixels at hue 355 and hue 5 were both kept, as they should be.
What is the saturation gate for?
A nearly grey pixel has a hue calculated from a tiny channel difference, so it is essentially noise and can match any target by accident. The gate refuses to match anything below a minimum colourfulness, which stops grey areas speckling.
What range should I use?
Start around 25 to 40 degrees. A real object is never one hue, since shadows push it one way and highlights the other, so a strict range will lose parts of your subject.
What does edge softness do?
It fades colour out over a range beyond your tolerance rather than cutting it off. A hard cut looks graphic and deliberate; a fade looks photographic.
Can I keep more than one colour?
Not in a single pass. Widening the range can cover neighbouring hues, such as orange along with red, but two colours on opposite sides of the wheel need two passes or a different tool.
What does invert mode do?
It flips the decision, so the colour you chose is the one that becomes grey and everything else keeps its colour. It is the quickest way to remove a single distracting colour from a scene.
Why did the background keep its colour too?
Something in it shares your target hue. Narrow the range, and check the picture before you shoot next time, since the effect is strongest when the chosen colour barely appears elsewhere.
Does it select by object or by colour?
By colour only. There is no subject detection here, so anything in the frame that shares the hue survives. That is also why it is completely predictable and never invents an edge.
Which photos work best?
Photos with one strong, saturated colour that does not repeat elsewhere. A red umbrella on a grey street is the archetype. Scenes where everything is warm-toned are the hardest.
Are my photos uploaded to a server?
No. The hue matching and the export both run in your browser using the canvas API. Nothing is sent anywhere and the tool keeps working if your connection drops after the page has loaded.
How is the grey calculated?
With Rec. 709 luminance weighting, which counts green far more than blue because that is how human vision works. It gives a much more natural monochrome than averaging the three channels.
Which format should I export?
PNG if you want the boundary between colour and grey held exactly, since JPEG stores colour at half resolution and can soften it slightly. Keeping the original format is fine for most photos.
Is transparency preserved?
Yes for PNG and WebP output. The alpha channel is untouched and only visible pixels are desaturated. JPG has no alpha, so transparent areas are filled with the background colour first.
Can I process a batch?
Yes. Add as many photos as you like and the same hue, range and gate are applied to each. Download individually or take the set as a single ZIP built in your browser.
Can the effect be undone?
No. The desaturated pixels lose their colour information permanently. Your uploaded file is never modified, so keep it, but the downloaded result cannot be reversed.
Does it add a watermark or need an account?
No to both. No sign-up, no email wall, no daily limit and no watermark on the output.