Halftone films
without a RIP

What a RIP actually does

RIP stands for raster image processor. On a screen printing bench it earns its keep in two ways, and they are worth separating because only one of them is hard to replace.

Job one: screening. Your artwork contains tones — a 40% grey, a gradient, a soft shadow. A screen printing press cannot print 40% of anything. It puts ink through an opening or it does not. So every tone has to be converted into a pattern of dots whose size varies with the tone: big dots for dark areas, small dots for light ones. This is amplitude-modulated screening, and mathematically it has been settled since the 1970s.

Job two: ink density. Films need to be genuinely opaque, or UV light leaks through the "black" areas and your emulsion hardens where it should have washed out. RIPs talk to the printer directly and dump far more ink than a normal photo print would.

Job one is a calculation. Job two is a driver setting. That distinction is the whole reason a browser can replace most of a RIP.

The three routes people actually take

1. Buy a RIP

Reliable, and expensive. Entry-level dedicated screen printing RIPs now run $200 to $500 a year as a subscription rather than a one-time licence, and full wide-format suites with colour management climb well past $1,500 a year. If you print daily, this is a sensible business expense. If you burn six screens a month, it is a lot of money to keep paying for.

2. The Photoshop bitmap route

Free if you already own Photoshop. Split channels, convert to greyscale, then Image → Mode → Bitmap → Halftone Screen, and fill in frequency, angle and shape. It works. It also asks you for numbers nobody teaches you, gives no feedback until you print, and has to be repeated for every ink on every job. Most people who post about it are asking which values to type.

3. Screen in the browser

A modern browser can do the pixel work fast enough to screen an A4 film in seconds. That is what PrintFilmReady does: it separates the artwork into inks, then converts each ink into a 1-bit film — pure black, pure white, no grey — sized to your mesh count. No install, no licence, no upload.

What "1-bit" means and why it matters

A 1-bit image has exactly two possible pixel values: black or white. That is what a film must be. If your film file contains grey pixels — because it was saved as a normal greyscale image, or because antialiasing softened the dot edges — those greys expose as partial hardening. The edges of your dots become mushy, fine dots wash away and shadow dots bleed together.

Any tool that hands you a "separation" as a flat colour layer has not done this step. You are holding artwork, not a film.

Getting the density right without a RIP

This is the part a browser cannot do for you, and anyone who says otherwise is selling something. The file leaves your machine as pure black; how much ink lands on the transparency is between you and the printer driver.

• Media type: choose a glossy photo paper setting. It tells the driver to lay down the most ink.
• Quality: highest available. Speed settings starve the film.
• Black ink only: if your driver offers it, use it. Composite blacks built from colour inks are less UV-opaque than pure carbon black.
• Colour management: off. You want raw values, not a profile trying to be tasteful.
• Scaling: 100%, never "fit to page". Scaling changes your dot size and your artwork dimensions in one go.

Hold the printed film up to a bright light. If you can see the lamp through the black, add density before you blame the file.

Where a browser genuinely cannot replace a RIP

Being honest about this is more useful than a longer feature list:

• Process colour work. Four-colour separations need dot gain curves per channel and careful angle management to avoid moiré and rosettes. That is RIP territory, and calibration takes weeks.
• Ink limiting and printer calibration. A RIP can be profiled to your exact printer and film stock.
• Very large formats where the file sizes and print pipeline need dedicated software.

For spot colour work — logos, type, bold illustration, two to six inks — none of that applies. The screening is the same mathematics either way.

A quick sanity check before you burn a screen

Print your first film, then run these three checks. They catch the overwhelming majority of problems and take a minute.

1. Measure it. The film should physically measure whatever width you asked for. If it does not, scaling was applied somewhere.
2. Look at the dots with a loupe. They should be crisp circles with hard edges, growing evenly from light to dark. Fuzzy edges mean the file was not 1-bit or the print quality was too low.
3. Hold it to the light. The black must be genuinely opaque.

Common questions

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