Apply CMYK separation, halftone screening, registration misalignment, ink density variation and paper texture to your artwork so it looks like a sheet that came off an offset press, a newspaper web press or a risograph. The processed result can be compared against the source image side by side.

What this tool does

The image you load is split into per-plate ink amounts and screened again with a halftone dot grid, each plate at its own ruling and screen angle. Three printing methods are available: CMYK four color process, single plate monochrome, and spot color with two or three inks in the manner of a risograph or a screen printing shop. Presets cover offset printing on coated stock, newspaper printing, a doujinshi monochrome interior, a risograph duotone and a retro print look. The screen angle and registration offset of every plate can be set by hand. The result exports as a PNG at the resolution of the source image (up to 4000px on the long edge) and the settings export as JSON.

Where this fits in your workflow

Mocking up a doujinshi cover, a zine or merchandise so a client or a printer can see it with the character of the final print.
Treating halftone grain and registration misalignment as a deliberate part of the illustration instead of an accident.
Checking, before you commit to a print method, how a drawing holds up once it is reduced to two risograph inks or to a single black plate.

How to use it

Pick the preset closest to the print method you have in mind, then drop your image onto the picker.
Switch the printing method between CMYK, monochrome and spot color. Spot inks can be chosen from the list of standard risograph colors or set freely with the color swatch.
Under Halftone screen, set the screen ruling, the print width, the dot shape and the dot gain. A narrower print width magnifies the screen so the individual dots become visible on your display.
On the Plates and paper panel, add misregistration, density variation, dry-out, and the color and texture of the stock.
In the plate list, type an angle and an offset for any single plate. Only the plates you touch leave the automatic distribution, and Reset plate adjustments puts them back.
Flip the preview between Processed, Source and Split to judge how far the treatment has gone.
Read the Warnings block, then export the PNG with Export at high resolution and the settings as JSON.

What each control means

Screen ruling (lpi): How many halftone dots sit in one inch. The higher the number, the finer the screen. Around 175 lpi is typical for offset on coated stock, 85 lpi for newsprint, and 60 lpi for a doujinshi monochrome interior.
Print width: How wide this image will physically be printed, in millimeters. Together with the screen ruling it decides how many pixels one halftone cell occupies on screen, and the current cell size is shown right under the field.
Dot gain: How much the ink spreads into the paper and fattens the dots. Coverage of 0% and 100% is preserved and only the midtones darken, which is what a tone value increase curve does on a real press. Uncoated and newsprint stocks gain the most.
Misregistration (offset and jitter): How far the plates sit out of register with each other. In CMYK the black plate is the reference, so line art stays put while the color plates shift around it.
Per plate angle and offset: Values you can override one plate at a time in the plate list, up to plus or minus 90 degrees and plus or minus 3mm. Any plate or field you leave alone keeps following the offset, the jitter and the random seed.
Density variation and dry-out: How much the ink laydown wanders across the sheet, and how much a solid breaks up and skips. The variation scale sets the size of the mottling pattern in millimeters.
Sampling: How many samples are evaluated per output pixel. Two or more removes the false moiré that appears where the rotated halftone grid interferes with the pixel grid of your display.

Reading the result and taking it into Clip Studio Paint

The plate list on Plates and paper shows the screen angle and the registration offset of every plate. Misregistration is invisible in flat solids; it only shows along edges and at the border of the image.
If you see fine stripes instead of dots, the screen is not being resolved at this preview size. Lower the ruling, reduce the print width so the screen is magnified, or raise the preview limit.
Export at high resolution re-renders from the source image (up to 4000px on the long edge) rather than from the preview, so the grain is finer than what you were looking at. A large image can take tens of seconds. The exported PNG can be imported into Clip Studio Paint and stacked as a layer over your artwork.
In spot color mode black never becomes a neutral black; it settles into a deep navy or violet. Two inks cannot mix a neutral, and that limitation is precisely what a risograph print looks like.

How the halftone and ink model works

For a cell of side s and a requested coverage a, the dot is drawn at the radius whose area matches exactly: r = s × √(a ÷ π) for a round dot, r = s × √a ÷ 2 for a square and r = s × √(a ÷ 2) for a diamond. Past 50% coverage the polarity flips and the paper is knocked out of a solid, the same way AM screening behaves on a real plate. Without that flip the corners of the cell survive and a 100% solid only reaches about 91% of the area with round dots, which reads as a muddy gray. Dot gain is applied as the coverage curve a + g × a × (1 − a) rather than by inflating the radius, so 0% and 100% stay put while only the midtones lift. The CMYK screen angles are 15, 75, 0 and 45 degrees, the classic arrangement that minimizes the rosette moiré between four plates. Color is composited as a product of measured ink transmittances in linear light instead of the idealized ink formula, which is why a solid of cyan, magenta and yellow lands on a warm dark brown-black rather than a pure black, exactly like a real three color overprint.

Accuracy, beta status and what is out of scope

This tool is in beta. The halftone, ink and paper models are simplifications tuned to reproduce the look, not a color managed simulation, and the real sheet will change with the press, the stock and the platemaking. Do not use it to decide whether data is ready for submission; check that with the print preflight tool instead. It is not a substitute for a contract proof either.

The CMYK estimate used for separation is an sRGB based approximation, not a conversion through an ICC profile. Because black is built from all four inks, the theoretical total area coverage goes past the usual submission limit.
Only AM screening, that is a regular halftone dot grid, is modeled. FM or stochastic screening and hybrid screens are not reproduced.
Export is capped at 4000px on the long edge, so the output is not usable as full size submission data.
Spot mode is limited to two or three inks. Beyond three there are not enough well separated screen angles left to avoid moiré.

How your image and settings are handled

Loading and processing both happen entirely inside your browser, and your image is never uploaded anywhere. The heavy rendering runs in a Web Worker in that same browser, so no network request is involved at any point. Your settings are kept in localStorage on this device so the tool comes back the way you left it; the image itself is never stored.

Frequently asked questions

I only see fine stripes, not halftone dots. What is wrong?

The preview resolution is too low for the ruling you asked for, so the screen cannot be resolved and you are looking at moiré instead of dots. Lower the screen ruling, make the print width smaller so the screen is magnified, or raise the preview limit. The Warnings block reports the same thing.

Can I send the processed image to a printer as submission data?

No. This is a look development tool built on a simplified model, and the export is capped at 4000px on the long edge. Build the data you submit from the original artwork and verify it with the print preflight tool.

I changed an ink color and the artwork almost disappeared.

An ink close to the color of the paper is indistinguishable from the bare sheet even as a solid, and the separation can no longer decide how much of that ink is needed, which is why the Warnings block calls it out. Choose a darker ink or lighten the paper color.

Will the same settings always produce the same image?

Yes. The registration jitter, the density variation, the dry-out and the paper grain are all derived from the random seed, so a given set of settings is fully reproducible.

Does this work for screen printing or a risograph zine?

Yes, that is what spot color mode is for. Choose two or three inks such as fluorescent pink and blue, raise the dot gain and the misregistration, and tint the paper towards an uncoated stock.