Two-plate separations
Screen printing with two colours needs two pieces of artwork that do not overlap. Invert one channel to get the second plate without redrawing anything.
Browser tool · 6 modes · 0 uploads
Image Negative
The negative of an image swaps light for dark on every channel. Printers use it for separations, designers for negative-space checks, and it costs one subtraction per pixel.
Drop an image, paste it, or click to choose
JPG · PNG · WebP · GIF · BMP — decoded on this device, never uploaded
Mode
Intensity
Output
Nothing is uploaded
The bytes stay in the tab. Clear the network panel, then invert a photo: no request appears, because the work happens in page memory.
Full resolution
No 2 MP preview cap, no server-side resize. A 48 MP frame comes back at 48 MP.
Six modes, not one
Whole image, a single channel, skin-safe, or dialled back to any strength between 0 and 100%.
About
What this conversion actually does
In prepress an "image negative" is a film or mask where the densities are reversed: the areas that will hold ink are clear and the areas that will stay paper are black. The purpose is practical — a plate, a stencil or a photoresist layer is built by removing material, so the artwork has to be delivered backwards.
In design the same operation is used to check composition. Invert a layout and figure-ground problems jump out: a shape that read as foreground becomes a hole, and a headline that was held up only by contrast disappears. The tool below does both jobs, and the single-channel modes matter more than they look — most separations are one colour at a time.
Specification
What it accepts, and what it returns
| Input formats | JPG, PNG, WebP, GIF (first frame), BMP, AVIF where the browser decodes it |
|---|---|
| Maximum size | No fixed cap. Tested to 8000 × 6000 (48 MP) on a machine with 8 GB of RAM |
| Speed | 1920 × 1080 in well under a second; 48 MP in about four seconds |
| Transparency | Alpha is never touched. PNG output keeps it, JPG output is flattened onto white |
| Output | PNG (lossless, alpha preserved) or JPG at quality 0.92 |
| Uploads | None. The file is read with the File API and drawn to a canvas that never leaves the page |
Modes
Six modes, and when each one is the right call
| Mode | What it does | When to use it |
|---|---|---|
| Full invert | 255 − value on R, G and B | A true negative. Also the base layer for duotone and print work. |
| Red channel only | R inverted, G and B untouched | Pushes the whole image toward cyan-green. One plate of a two-colour screen print. |
| Green channel only | G inverted, R and B untouched | Magenta shift. Good for testing how a muted palette reads in print. |
| Blue channel only | B inverted, R and G untouched | Yellow shift. Useful for warm/cool split toning without a curve tool. |
| Smart invert (keeps skin) | Skips pixels inside the skin-tone range | Portraits. Faces stay recognisable while the background turns into a negative. |
| Intensity 0–100% | Blends the negative with the original | Anything that needs a hint of the effect rather than a full inversion. |
Method
Three steps
Start from the artwork, not the photo
Flatten transparency before inverting if the file is going to a RIP. A semi-transparent edge inverts into a semi-transparent edge of the opposite colour, which is rarely what a printer wants.
Invert the channel you are separating
For a two-colour job, invert the red channel only: the result is a usable cyan plate while green and blue keep the image readable. Full invert is for a single-plate stencil.
Check the edges at 100%
Inversion does not anti-alias anything. Edge pixels that were blended between subject and background keep their blend, which can produce a thin halo after printing. Zoom in before you send the file.
Use cases
What people actually use it for
Photoresist and PCB masks
Etching removes copper where the mask is clear, so the mask is the negative of the trace layer. Invert a board render to preview what the etchant will see.
Negative-space audits
Invert a poster or a slide and the holes become shapes. If the inverted layout still balances, the composition is doing real work rather than relying on the background.
Stencils and vinyl cuts
A cutter follows the paths you give it, but a stencil needs the gaps cut out. Invert the design, trace the result, and the bridges fall in the right place.
Displacement and roughness maps
3D texture maps care about tonal range, not colour. Invert a concrete or fabric photo and it becomes a usable height map with the highlights where the pits were.
Legibility testing
Set a block of text on its own background, invert it, and read it again. Text that survives the inversion is text with enough weight and spacing to survive a bad projector.
Under the hood
Why channel-independent inversion is useful
Inverting all three channels is a point reflection through mid-grey: every colour moves to its complement and the luminance histogram reverses. Inverting one channel is a different operation — it leaves two dimensions of colour untouched, so the image keeps its tonal structure and rotates in hue instead.
That distinction is why "invert" in a print context usually means "invert the separation", not "invert the picture". If you invert the whole frame before separating, the densities of the other two plates are wrong and the print comes out muddy.
Questions
Answered plainly
Is an image negative the same as a grayscale invert?
No. A grayscale invert throws away colour first and then inverts one channel, so the result is monochrome. This tool inverts each channel in place, so colour survives — a red area becomes cyan, not dark grey.
Is a negative the same as a complementary colour?
In RGB, yes: the complement of a colour is exactly 255 minus each channel, so inverting a red pixel gives cyan. In paint the complement is defined on a different wheel, which is why the two answers disagree.
Can I invert an SVG?
Not directly — the browser rasterises it first. Open the SVG at the size you need, screenshot or export a PNG, then invert. Vector paths themselves are untouched by a pixel operation.
Does inverting change the file size?
The pixel count is identical, so PNG size barely moves — the data is just as compressible. JPEG size can shift either way, because the encoder meets different frequency content.
Which channel should I invert for a cyan plate?
Red. Cyan ink absorbs red light, so the cyan separation is the inverse of the red channel. Invert red only and leave green and blue alone to preview it.
Does it handle CMYK files?
Browsers decode to RGB, so a CMYK file arrives already converted and the fourth channel is gone. For contract proofs, do the inversion in the RIP or in a CMYK-aware editor.
What comes next
A server-side API and a desktop batch runner are planned. The browser tool above stays free and unlimited: no account, no watermark, no file cap.
Free, permanently
Full resolution, all six modes, batch and ZIP. If a page ever asks you to register to invert an image, it is not this one.
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