Last updated: October 2026
Quick answer: A CTP RIP (raster image processor) turns print-ready PDF files into the 1-bit screened data a platesetter images. Along the way it applies imposition, trapping, screening and calibration curves. Those curves, not just the plate, decide how tints print, so a plate change usually needs linearisation and a press curve check in your existing RIP rather than a new workflow.
Key takeaways
- The RIP controls screening and calibration curves, so it decides how tints print as much as the plate does.
- A typical workflow runs preflight, normalise, impose, trap, RIP, proof and output to the platesetter.
- Changing plates usually needs linearisation and a press curve check, not a new workflow.
- Most “plate problems” with tints are curve or screening problems; check the RIP before changing exposure.
Every CTP plate starts as a file. Between the designer’s PDF and the imaged plate sits the RIP and its workflow server, the part of prepress most printers know least about. When the tints on press do not match the proof, or files fail at the RIP and the platesetter waits, the cause is often in this chain. This guide explains the steps in plain terms, without tying them to any particular software product. New to CTP? Start with what CTP printing is, and keep our CTP glossary open for terms.
What a RIP does in a CTP workflow
Many people see the RIP as a file converter that sends jobs to the platesetter. It does more. The RIP interprets the page description (PDF), separates colours, converts every tone into dots through screening, applies calibration curves so the plate carries the right dot sizes, and outputs a 1-bit image per colour. The platesetter then simply switches its laser on or off for each pixel.
In most plate rooms the RIP runs inside a workflow server that also handles preflight, imposition, proofing and job queues. When you buy a platesetter from us, RIP software is normally included or offered as an option (confirmed in the quotation), and an existing RIP can drive the new machine through 1-bit TIFF output. The CTP platesetters we offer are supplied with our partner factories; output connection options are listed on the machine specification sheet.
The CTP RIP workflow step by step
- Receive and preflight. Check incoming PDFs for missing fonts, low-resolution images, wrong colour spaces, missing bleed and overprint settings.
- Normalise. Convert files into a consistent PDF standard so every later step behaves predictably.
- Impose. Place pages on the press sheet according to the press, sheet size, folding and binding. Add marks, colour bars and the plate control strip.
- Trap. Add small overlaps between touching colours to hide press misregistration.
- RIP and screen. Separate colours, apply screening and calibration curves, and render 1-bit data for each plate.
- Proof. Make a contract or imposition proof from the same RIP data so the proof matches the plates.
- Output. Send the 1-bit data (often as 1-bit TIFF, also called TIFF-B) to the platesetter queue, with the correct plate size and punch layout.
- Verify. Measure the control strip on the processed plate and log the result.
Screening: AM, FM and hybrid
| Screening | How it works | Strengths | Watch out for |
|---|---|---|---|
| AM (conventional) | Dots vary in size on a fixed grid and angle | Familiar, forgiving on press, easy to control | Moiré and rosettes in some images |
| FM (stochastic) | Same-size small dots vary in frequency | Fine detail, no moiré, smooth images | Needs a stable plate and press; small dots must hold on the plate |
| Hybrid | AM in midtones, FM-like in highlights and shadows | Fine detail with AM stability | Needs its own calibration |
Which screening a plate can hold depends on the plate grade, exposure and processing. Check the resolution capability on the grade TDS and run a test before switching screening on production work. Our thermal CTP plates and CTcP plates each list their TDS test conditions.
Calibration curves: linearisation and press curves
Two different curves are often confused:
- Linearisation (plate curve). Makes the dot on the plate match the value in the file, for example a 50% tint measures as 50% on the plate. It compensates for the plate, exposure and processing.
- Press curve (dot gain compensation). Adjusts plate values so the printed result matches a target print condition. It compensates for paper, ink, blankets and press.
When a new plate made everything print darker, the usual cause is a missing or outdated linearisation. Changing plates rarely means changing the whole workflow. A new plate usually needs only linearisation and a press curve check in your existing RIP. That is exactly what a structured plate trial covers; see our plate test protocol and CTP compatibility guide. If you were told the RIP only works with one plate brand, ask what is actually locked; thermal platesetters image 830 nm thermal plates, and curves are created per plate in the RIP.
“Recalibrating takes too long” is a fair objection, but a linearisation is a short task with a plate densitometer once exposure and processing are stable. Skipping it costs more on press.
Workflow server, output formats and connection to the platesetter
Most platesetters accept data either directly from a connected RIP or as 1-bit TIFF files from a workflow server. Things to agree before installation:
- Which RIP drives the platesetter, and whether output is direct or via 1-bit TIFF.
- Plate sizes, image position and punch layout defined as output presets per press.
- Network connection, file storage and backup of curves and presets.
- Who owns calibration: the prepress operator, the platesetter supplier or a service bureau.
Prepress service bureaus that make plates for many presses usually keep one preset and one press curve per customer press; see our page for prepress service bureaus.
Troubleshooting RIP and output problems
| Symptom | Likely RIP or workflow cause | Check |
|---|---|---|
| Tints print too dark or too light | Wrong or missing curve | Plate linearisation, press curve, curve assigned to the job |
| Proof does not match press | Proof and plates from different settings | Same RIP data and colour settings for both |
| Missing text or objects | Font or transparency problem | Preflight report, normalised PDF |
| Moiré in images | Screen angles or frequency | Screening set; consider hybrid or FM |
| Image off-centre or wrong size | Output preset | Plate size, image position, punch layout |
| Jobs stuck in queue | Connection or storage | Network, disk space, platesetter status |
What not to do
- Do not change laser exposure to fix a tint problem that belongs to the curve.
- Do not linearise while the processor developer is exhausted or unstable; fix the processor first.
- Do not stack several press curves on one job.
- Do not overwrite curves without a dated backup.
- Do not skip preflight on “urgent” jobs; they are the ones that fail.
Keep the platesetter itself in good condition too; see our CTP machine maintenance routine.
FAQ
What is a RIP in CTP?
A RIP (raster image processor) converts PDF pages into screened 1-bit data that the platesetter images. It also applies imposition, trapping, screening and calibration curves.
What file format does a platesetter need?
The RIP takes print-ready PDF and sends 1-bit screened data to the platesetter, either directly or as 1-bit TIFF files. Check the supported input on the machine specification sheet.
What is a 1-bit TIFF in prepress?
A 1-bit TIFF, also called TIFF-B, is a screened image where each pixel is either on or off. It is the final per-colour data a platesetter images.
Why do I need calibration curves for CTP plates?
Linearisation makes the plate dot match the file value, and the press curve makes the printed result match your target. Without them, tints print too dark or too light.
Does a CTP machine come with RIP software?
It depends on the configuration. Our platesetters normally come with RIP software included or as an option, confirmed in the quotation; if you already run a RIP, the platesetter can also take its 1-bit TIFF output.
AM or FM screening: which is better for CTP?
AM is familiar and forgiving; FM gives finer detail but needs a stable plate and press. Many printers use hybrid screening. Test on your plate and press before switching.
Changing plates or adding a platesetter? Request a quote — send your RIP output method, plate sizes, screening and press list, and we will plan trial plates and calibration with you. Or request trial plates / contact us.
Disclaimer: values on this page are typical and for reference only; final specifications, MOQ, price and lead time are subject to the grade TDS and the quotation.
