A print shop that asks for a CMYK PDF wants colours defined for ink on paper, not for a screen. A PDF can mix both: a CMYK page layout with one RGB logo, a gray text colour, a spot colour for a varnish. This checker reads the page content, the colour spaces and the images of a PDF and tells you which colour spaces are actually used to paint, on which pages and by how many objects, so you know what to convert before the file goes to print.
It is a preflight colour inspection. It does not say that a PDF is print-ready: ink limits, overprint, fonts, bleed and your printer's own requirements are separate checks. The file is analysed in your browser and not uploaded.
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Overview
About PDF Colour Space Checker for Print
What is read. The page content streams are read operator by operator (pdf.js converts all colours to RGB internally, which would hide the originals), together with the resources they use: Form XObjects, patterns, shadings, images and ExtGState entries. The colour in effect when something is actually painted is recorded: vector fills and strokes, text, images, shadings and stencil masks. A colour that is set but never used for painting is not counted. Text with no colour operator is painted in the default DeviceGray black, which is reported as gray, and that is normal.
The families. RGB (DeviceRGB, CalRGB and ICC-based RGB profiles), CMYK (DeviceCMYK and ICC-based CMYK), gray (DeviceGray, CalGray, ICC gray), spot colours (Separation colour spaces, listed by name, with process-colour names and "All" recognised), DeviceN, Lab, Indexed palettes (reported with the family of their base) and patterns. ICC profiles are described from their header (data colour space and description). Images list their colour space, size, bits per component and filter; JPEG 2000 images whose colour space is defined inside the data are marked as such.
Print-related indicators. Output intents (type such as GTS_PDFX, identifier, condition, registry and the profile\'s components and description), the PDF/X version declared in the document information or the XMP metadata (shown as the file\'s own claim, not validated), transparency features (blend modes, soft masks, opacity, groups with their colour space), overprint settings, and per-page TrimBox, BleedBox and ArtBox, which PDF/X requires in part. A plain-language summary lists, for example, "RGB colour is used on 2 of 3 pages: 1, 3".
Use it with a conversion step. If RGB is reported, convert those objects in your layout application with the print shop\'s profile, export again and re-check.
Compatibility
Supported Formats
PDF files up to 80 MB and 500 pages, without a password. Not inspected: colours in annotation appearance streams and in Type 3 glyph procedures, and uncommon encodings. Raster images are listed with their colour space but their pixels are not analysed.
Guide
How to Use PDF Colour Space Checker for Print
- Drop the PDF onto the box (up to 80 MB).
- Read the summary: pages with RGB, CMYK, gray and spot colours, and the output intent.
- Check "colour spaces used to paint" and the page-by-page table to find what to convert.
- Fix the file in your layout program, export again and re-check. Download the JSON report if your printer wants a record.
Highlights
Features
- RGB, CMYK, gray and spot The colour spaces actually used to paint, per page and per object type.
- ICC and DeviceN details Profile descriptions, spot names and alternate spaces.
- Output intent and PDF/X claim What the file states about its printing condition, not validated.
- Images listed Colour space, size, bits and filter of each image.
- Preflight, not a promise A colour inspection that says what it does not check.
Applications
Use Cases
- Finding out whether a PDF for print still contains RGB images or text
- Listing the spot colours (for example PANTONE) a design uses
- Checking whether an output intent such as FOGRA39 is embedded
- Seeing which pages use transparency before choosing PDF/X-1a or PDF/X-4
- Comparing the colour spaces before and after a conversion
Good to Know
Limitations
This is a preflight colour inspection. It does not say that a PDF is print-ready, does not validate PDF/X conformance (the declaration is shown as the file's own claim), and does not measure total ink coverage, check overprint results, fonts, bleed, trapping or resolution. The final judgement belongs to your printer's own preflight.
Colour spaces are read from the content streams and resources, so a PDF with unusual or damaged structure may be reported incompletely. Gray in DeviceGray is normal for black text. RGB that is set but not painted is not counted, and RGB in a soft mask or an annotation appearance may not be seen.
This tool runs entirely in your browser — your file is never uploaded to our servers. See our Privacy Policy for full details.
Support
Frequently Asked Questions
Is my PDF uploaded?
No. The PDF is analysed in your browser and is not sent to our server.
Does this tell me my PDF is print-ready?
No. It is a colour inspection only. Ink limits, overprint, fonts, bleed, trapping and your printer's requirements are separate checks.
Why does my CMYK PDF show gray?
Black text is often set in DeviceGray, which prints with black ink only. That is normal and usually wanted.
What is an output intent?
An entry that names the printing condition the colours are meant for (for example FOGRA39 or a US coated profile). PDF/X files carry one; its absence means the file does not state a target condition.
Does the tool convert RGB to CMYK?
No. It shows what to convert. Do the conversion in your layout application with the profile your printer asks for.
What are spot colours?
Named inks such as PANTONE colours (Separation colour spaces). Each needs its own plate unless it is converted to CMYK.
Keep Going
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