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Guided workflow variation

RGB, CMYK or spot?See what each page uses.

Screens mix red, green and blue light, while presses lay down cyan, magenta, yellow and black ink. ProofSlip lists every color space a PDF uses with its pages, names the spot inks and output intent, and leaves conversion to you and the printer.

ProofSlip warns on RGB and Lab, notes spot colors and a missing output intent, and lists the pages for each color space. It reports and never converts.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Full ProofSlip overview
One-time purchase No telemetry Local-first

windows · one-page pass or fail · original never written · nothing uploads

If this sounds like your week

Vivid RGB greens and blues can turn dull on press.

Artwork made for screens is often RGB throughout: photos straight off a phone, brand shades picked by hex value, charts pasted from a spreadsheet. Process inks reproduce a narrower range than a monitor shows, so some saturated tones shift when the document is converted for printing. If nobody knew the layout was RGB, that shift happens somewhere downstream and the client is surprised by the result.

Where tooling usually breaks

Color hides in objects, pictures and transparency.

One PDF can mix several spaces at once: a CMYK background, an RGB photograph, a spot ink for a logo, a grayscale scan. Viewers reveal none of it. Inspecting objects individually in an editor is tedious, and a printer's question is broader anyway: which pages contain RGB, which named inks may need their own plates, and does the document declare an output condition at all?

Where ProofSlip lands

A color summary by page, with ink names and intent.

ProofSlip counts color from fills, strokes, pictures, shadings and transparency groups, then lists each family with its pages: Gray, RGB, CMYK, Lab, Spot, plus ICC-based variants. RGB and Lab are warnings, spot inks get an INFO note naming every one, and a missing output intent is noted. A declared PDF/X version is shown as what the document declares. Nothing is converted; ProofSlip reports.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Learn more about ProofSlip

windows · one-page pass or fail · original never written · nothing uploads

What you get

Feature highlights

One verdict, every finding graded

a single PASS or FAIL at the top, with each finding marked FAIL, WARN or INFO and the pages it affects, so the warnings are read as well as the verdict.

Fonts with the pages that use them

every font with its type, subset tag and embedding, and a FAIL when a font that paints visible text is not embedded, including the standard 14 base fonts.

Image ppi where it is placed

effective ppi for every placement, measured from the page itself and sorted lowest first, failing color and grayscale images below 150 ppi and 1-bit images below 300.

Trim, bleed and page size

size from the trim box or media box, named sizes such as A4 and Letter, and bleed on each side in millimeters, with a warning under 3 mm.

Color spaces page by page

Gray, RGB, CMYK, Lab and spot colors with their pages, every spot name and the output intent; RGB and Lab are warnings, and nothing is converted.

A report you can send, and an untouched original

a one-page PDF report or an HTML report saved as a new file, while the source PDF is opened read-only, never written, and nothing uploads.

Especially when

  • Check a client PDF for unembedded fonts, low-resolution images, RGB color and missing bleed on a Windows PC without uploading it
  • See the effective ppi of every placed image in a PDF instead of measuring each one by hand
  • Send a client a one-page report that names each problem and the pages it affects
  • Preflight print files without paying for professional prepress software or a PDF editor subscription

Who benefits

Real-world scenarios

A brochure with phone photos

A client's brochure uses CMYK for text and backgrounds but places six photos taken straight from a phone, which are RGB images.

ProofSlip shows a warning, RGB colour on pages 2–4, 7; not CMYK, and the Images table shows RGB in each photo's Colour column. The shop and the client decide whether to convert the photos before printing or let the print workflow handle it.

A letterhead in two spot inks

A letterhead for an offset run uses two spot inks for the logo, and the printer wants to confirm the ink names before plates are made.

The Colour summary and an INFO finding list both spot names exactly as the file spells them, so a misspelled duplicate or a third version of the same ink stands out before any plate is made.

An ad that declares an output condition

A magazine ad arrives with a note saying it was exported to a PDF/X standard for a coated paper condition, and the shop wants to see what the file itself says.

ProofSlip shows the output intent's condition identifier and the declared PDF/X version, followed by the line: ProofSlip reports the declaration and does not validate it. Conformance remains a separate check.

Deep dive

Reading a PDF's color spaces before it goes to press

Device, calibrated and ICC-based color. Every PDF object names the color space it is painted in. DeviceRGB, CalRGB and ICC profiles with three components are all RGB. DeviceCMYK and four-component ICC profiles are CMYK. DeviceGray, CalGray and one-component profiles are grayscale. ProofSlip groups these into families and marks the ICC-based ones, so the summary reads ICC RGB rather than a raw object name.

Spot colors. A Separation or DeviceN color space names inks outside the four process colors. ProofSlip lists each spot name, leaves out the process inks cyan, magenta, yellow and black, and reports the All colorant as registration. Spot colors are an INFO note rather than a warning, because many jobs use them on purpose.

Where color is counted. Fill and stroke colors, images, inline images, shadings and shading patterns, and the blending space of transparency groups all count. Indexed images count as their base space. That is why a file whose visible objects are CMYK can still show RGB: an image or a transparency group may use it. The Colour summary lists the pages for each family, so you can go straight to them.

Output intent and PDF/X. An output intent names the printing condition a file was prepared for, such as a coated paper standard. ProofSlip lists any output intents and adds a note when there is none. If the file declares a PDF/X version, ProofSlip shows it with the statement that it reports the declaration and does not validate it. A declared version is information, not proof of conformance.

Why RGB is a warning, not a failure. Some print workflows accept RGB and convert it with a known profile; others ask for CMYK only. ProofSlip cannot know which applies, so it warns and lists the pages. If your printer wants CMYK only, treat the RGB warning as a failure for that job. Lab color is warned for the same reason.

What ProofSlip will not do. It never converts color, never turns a spot ink into process, and never applies a profile, and the original PDF is not written. Conversion belongs in the design app or the printer's workflow, where the right profile for the paper and press is known. The report is a check, not a fix.

How it is built

Built to read the file and leave it alone.

Read-only by design

The PDF is opened read-only through the Windows file picker and never written. Reports are new files, and saving over the file being checked is refused.

Nothing leaves your PC

ProofSlip runs in a Windows app container with no network capability. There is no account and no telemetry. One-time purchase in the Microsoft Store.

A check, not a fix

It reports what the file contains and declares. It does not embed fonts, convert color, resample images or flatten, and it does not validate PDF/X.

FAQ

Straight answers—no glossary dump

How do I check if a PDF is RGB or CMYK?

A PDF can be both, so look for every color space it uses rather than one setting. In ProofSlip, choose Open PDF and read the Colour summary under the tables: it lists Gray, RGB, CMYK, Lab and Spot with the pages for each. RGB anywhere in the file is a warning that names the pages, and the Images table shows each image's color space in its Colour column.

Will ProofSlip convert RGB to CMYK?

No. ProofSlip reports color and never changes it, and the original PDF is never written. Convert in the application that made the file, using the profile your printer asks for, or ask the printer whether its workflow will convert RGB on its own. Then open the new export in ProofSlip and check that the RGB warning is gone, or that it remains only where you meant it to be.

What is an output intent, and does my file need one?

An output intent is a declaration inside the PDF naming the printing condition the colors were prepared for, such as a coated paper standard, often with an ICC profile. PDF/X files carry one. Many print jobs do not need it, which is why ProofSlip only adds an INFO note when it is missing. If your printer asks for PDF/X or a specific condition, check the Colour summary.

Does a PASS mean the file will print as intended?

No. A PASS means ProofSlip found no failing finding: every font that draws text is embedded, no image is below the fail limits, and every page could be read. RGB color and thin or missing bleed are warnings, so read them too. ProofSlip does not render pages, so it cannot see artwork that stops short of the bleed, text too close to the trim, overprint, transparency or ink build-up, and it does not validate PDF/X conformance. Your printer's spec sheet has the final word.

Will ProofSlip change my PDF?

No. The PDF is opened read-only and is never written. ProofSlip is a check, not a fix: it does not embed fonts, convert color, resample images, add bleed or flatten anything. Each report is saved as a new file with a suggested name such as brochure-proofslip.pdf. If you pick the PDF being checked as the destination, ProofSlip refuses with a message that it is the file being checked, so the original cannot be overwritten by mistake.

Does anything leave my PC, and how do I get ProofSlip?

Nothing uploads. ProofSlip has no account and no telemetry, and it runs in a Windows app container that declares no network capability. It reads only the PDF you pick in the Windows Open dialog and writes only the report you save. It runs on Windows 10 version 2004 or later and on Windows 11, on x64 and ARM64 PCs. ProofSlip is a one-time purchase in the Microsoft Store, and the Store gives you a 15-day free trial of the full app, so you can check your own files before you buy.

Related pages

A preflight check for client PDFs, run on this PC. Every font in the PDF, and whether it is embedded. Trim, bleed and page size, read from the file itself.

The PDF looks fine on screen.
Check it before the press does.

ProofSlip reads a client PDF on your PC and reports embedded fonts, page size, trim and bleed boxes, color spaces and effective image resolution, with one PASS or FAIL and a report you can send. It is a check, not a fix, and nothing uploads.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Open full product page

Technical specifications

Technical specifications for procurement

Spec Implementation
Data Sovereignty Reads only the PDF you pick in the Windows Open dialog, read-only; writes only the report you save as a new file; the Recent list (up to 20 files) and window size stay in the app’s own settings on this PC
Telemetry Status None; no account, no analytics, and no crash upload (a local error log keeps error types only, never file names or contents)
Core Runtime .NET 10 and WinUI 3 (Windows App SDK), packaged as MSIX; runs in an AppContainer that declares no capabilities
Network Requirements Fully functional offline; no network capability is declared, and the app makes no network connections
Deployment Compatibility Windows 10 version 2004 or later and Windows 11, x64 and ARM64; one-time purchase on the Microsoft Store with a 15-day free trial
Checks Embedded fonts, page size and named size, trim and bleed boxes with bleed per side, color spaces with spot names and output intent, and effective image resolution per placement
Verdict FAIL for a used font that is not embedded, color or grayscale images under 150 ppi, 1-bit images under 300 ppi, or unreadable content; WARN and INFO for the rest; limits are fixed in this version
Reports One-page PDF report (Letter or A4, matched to the file) and a self-contained HTML report with the full lists, both saved as new files
Originals Opened read-only and never written; saving a report over the file being checked is refused
Input One PDF at a time; files that need a password to open are refused, and files with only an owner password open read-only
Not included No fixing, color conversion or flattening; no page preview, batch checking or PDF/X validation