CTP Glossary: CTcP Meaning and Prepress Terms Explained

By Peter Zhang, Sales Manager, CTPPress

Last updated: October 2026

Quick answer: CTcP means computer-to-conventional-plate: a computer to plate method in which a UV light source images UV-sensitive, conventional-type offset plates directly from digital files, without film. It differs from thermal CTP, which uses 830 nm infrared lasers and thermal plates. CTcP plates are handled under yellow safelight and developed in a plate processor.

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Key takeaways

CTcP = computer-to-conventional-plate: UV imaging of conventional-type plates without film.
CTP is the umbrella term; thermal, CTcP (UV) and violet are its main branches.
Each platesetter type needs its matching plate type and developer.
Use the A to Z sections below to share consistent terms with your team and suppliers.

Supplier quotes, plate data sheets and machine specifications are full of abbreviations: CTP, CTcP, PS, RIP, LAMS. If you are confused between CTP and CTcP plates, or your new operators don’t know the prepress terms yet, this glossary is for you. We kept the definitions short and practical, and where a term affects what you buy, we say how. Terms also differ between suppliers, so where two names mean the same thing, both are listed. It is plain prepress terminology for buyers and operators, not a textbook, and you can share it with your team. It covers:

Offset plate terminology: plate types, coatings, substrate, grain and anodising.
Imaging terms: platesetter, RIP, exposure, linearisation and dot gain.
Processing and pressroom terms: developer, gum, baking, scumming and toning.
A few flexo terms buyers meet in quotes, such as LAMS.

What does CTcP mean?

CTcP meaning: CTcP stands for computer-to-conventional-plate. It is a form of computer to plate (CTP) imaging in which a UV light source exposes a UV-sensitive, conventional-type offset plate directly from digital files, with no film. The plates are similar in chemistry to traditional positive PS plates, and they are handled under yellow safelight and developed in a plate processor.

Many people think CTcP is just another name for thermal CTP. It is not. Thermal CTP uses 830 nm infrared lasers and thermal plates; CTcP uses UV exposure and CTcP plates, imaged on a UV CTcP platesetter. Knowing a few key terms like this helps buyers compare quotations on the same terms and choose the right plate for their machine.

A CTcP plate: a UV-sensitive conventional-type plate imaged directly on a UV platesetter.

CTP vs CTcP vs PS plates at a glance

Term	How the plate is imaged	Handling light	Our related products
Thermal CTP	830 nm infrared laser in a thermal platesetter	Daylight / normal room light	Thermal CTP plates
CTcP (UV CTP)	UV light source in a CTcP platesetter	Yellow safelight	Single-layer CTcP plates
Violet CTP	Violet laser diode in a violet platesetter	Yellow safelight	Violet photopolymer plates
PS plate (conventional)	UV contact exposure through film	Yellow safelight	Positive PS plates
Processless plate	830 nm thermal laser; no chemical processing	Daylight / normal room light	Processless CTP plates

The terms buyers mix up most often:

CTP vs CTcP: CTP is the umbrella term; CTcP is the UV branch of it.
Platesetter vs imagesetter: a platesetter images plates; an imagesetter images film.
Processless vs chemistry-free: used loosely in the market; check whether a processor or gumming unit is still needed.

Glossary A to C

Ablation: Removing a thin layer with laser energy. In flexo, the laser ablates the black LAMS mask on a digital plate; some offset plates are also ablation-type.
Anodising (anodizing): An electrochemical treatment that builds a hard aluminium oxide layer on the grained plate surface. It gives the non-image area wear resistance and water receptivity.
Baking: Heating a developed, bakeable plate in a plate baking oven to harden the image for longer runs. Only some plate grades can be baked; check the TDS.
Coating: The light- or heat-sensitive layer on the plate. Single-layer and double-layer thermal plates differ in how this coating is built.
Conductivity: A measure of developer activity (and of fountain solution strength). Falling developer conductivity usually means the bath is getting tired.
CTP (computer to plate): Imaging printing plates directly from digital files, without film. Covers thermal, CTcP (UV) and violet systems. See what CTP printing is.
CTcP (computer-to-conventional-plate): CTP with UV exposure of conventional-type plates. See the definition above.

Glossary D to L

Developer: The alkaline chemistry that removes the soluble coating after exposure. Thermal, CTcP and PS plates each need a matched CTP or PS developer.
Dot gain: The increase in printed dot size compared with the dot on file or plate, caused by ink spread and press conditions. Process standards such as ISO 12647-2 give dot gain (tone value increase) targets for offset printing; the RIP compensates with curves.
Double-layer thermal plate: A thermal plate with two coating layers, designed for better chemical resistance and longer runs than single-layer grades.
Exposure: The energy delivered to the plate coating by the laser or UV lamp. Set it with a test wedge for each plate grade.
Format (4-up, 8-up, VLF): How many letter or A4 pages fit on one plate. 4-up matches B2 presses, 8-up matches B1 presses, and VLF (very large format) covers presses above B1. See the plate size chart.
Gauge: Plate thickness. Common offset gauges are 0.15 mm, 0.20 mm, 0.25 mm and 0.30 mm.
Grain (graining): The fine, rough texture given to the aluminium surface before anodising. Grain holds water in non-image areas and anchors the coating.
Gum: A protective film applied after development to keep non-image areas water-receptive and protect the plate before printing.
Imagesetter: A device that images film, used before CTP. Film was then contact-exposed onto PS plates.
LAMS (laser ablation mask system): A thin black mask layer on digital flexo plates. The flexo imager ablates the mask, then the plate is UV-exposed through it. See digital flexo plates.
Linearisation: Calibrating the RIP so that a requested dot value is reproduced accurately on the plate.

Glossary M to R

Negative-working plate: A plate where exposed areas become the image. Violet photopolymer and processless plates are negative-working. Note that we do not supply negative PS plates.
Platesetter: The CTP machine that images plates from digital files. Platesetter meaning in practice: the thermal, UV or violet “engine” of the CTP line. See our CTP machine range.
Plate processor: The machine that develops, rinses, gums and dries plates after imaging. See plate processors.
Positive-working plate: A plate where exposed areas are removed in the developer and unexposed areas form the image. Most thermal, CTcP and PS plates are positive-working.
Preheat: A heating step before development, used mainly with photopolymer (for example violet) plates to harden the exposed image.
Processless plate: A thermal plate that needs no developer: the non-image coating is removed on press by ink and fountain solution.
PS plate (presensitised plate): A conventional plate exposed through film with UV light.
Punching and bending: Making register holes and bending the plate edges so it mounts accurately on the press. Done with a plate punch and plate bender.
Replenishment: Adding fresh developer automatically, per plate area and over time, to keep activity stable.
RIP (raster image processor): Software that converts PDF pages into the screened bitmap the platesetter images. It also applies curves and imposition.
Run length: How many impressions a plate gives before image wear. It depends on plate grade, baking, press, ink and paper; check the grade TDS.

Glossary S to Z

Safelight: Filtered (usually yellow) light that does not expose UV- or violet-sensitive plates.
Scumming and toning: Ink in non-image areas. See our CTP plate troubleshooting guide.
Slip sheet (interleaf): Paper between plates in the box to prevent scratches. Automatic loaders remove it.
Substrate: The base material of the plate, usually grained and anodised aluminium; polyester or paper for some low-cost offset plates. See aluminium plate substrates.
TDS (technical data sheet): The document listing a plate grade’s sensitivity, processing conditions, storage and other properties.
Thermal plate: An offset plate imaged by 830 nm infrared laser heat. Can be handled in normal light.
UV CTP: Another name for CTcP.
Violet CTP: CTP using a violet laser diode and violet-sensitive plates; today mainly used in newspaper production.

Glossaries can feel too technical, and definitions alone don’t tell you what to buy. If you want to know which plate type your machine needs, these pages go further:

Our resources hub, with size charts, compatibility checks and selection guides.
The CTP plate compatibility guide, to match plates to your platesetter.
The types of CTP plates explained side by side.

FAQ

What does CTcP mean in printing?

CTcP means computer-to-conventional-plate. It is a CTP method that uses a UV light source to image UV-sensitive conventional-type offset plates directly from digital files, without film.

What is the difference between CTP and CTcP?

CTP (computer to plate) is the general term for imaging plates without film. CTcP is one type of CTP that uses UV exposure and conventional-type plates; thermal CTP uses 830 nm lasers and thermal plates.

What does platesetter mean?

A platesetter is the CTP machine that images printing plates directly from digital files using a laser or UV light source. Thermal, UV (CTcP) and violet platesetters each need their matching plate type.

What is a RIP in prepress?

A RIP (raster image processor) is software that converts PDF pages into the screened image a platesetter writes onto the plate, applying curves, screening and imposition.

What is dot gain in offset printing?

Dot gain is the increase in printed dot size compared with the file or plate, caused by ink spread and press conditions. It is controlled with RIP curves and process standards such as ISO 12647-2.

What does LAMS mean in flexo?

LAMS stands for laser ablation mask system: a thin black mask on digital flexo plates. A flexo imager ablates the mask and the plate is then UV-exposed through it.

What is a processless plate?

A processless plate is a thermal CTP plate that needs no developer or processor. After imaging, the non-image coating is removed on press by ink and fountain solution.

Not sure which plate your platesetter needs? Request a quote — send your platesetter type, press size and current plate grade. 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.