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The resolution that mattersis the one on the page.

The ppi tag inside an image file says little about print. What counts is how many pixels land on each inch of paper once the picture is scaled in the layout. ProofSlip measures that for every placement and sorts the lowest first.

ProofSlip reports effective ppi for every placed image, fails color and grayscale images below 150 ppi, warns below 300, and applies stricter limits to 1-bit art.

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

A sharp picture on screen can still print soft.

A logo copied from a website, or a photo enlarged to fill a panel, looks crisp at screen zoom, because a monitor needs far fewer dots per inch than paper. Printed at full size, that same picture turns soft or blocky. Its pixel count never changed; it was simply stretched across more inches than it can cover, and the exported document gives no hint that anything is wrong.

Where tooling usually breaks

Image properties answer a different question.

Open the original picture and its properties often say 72 or 300 ppi, a tag written by a camera or editor that ignores how large it was later placed. Working it out manually means finding pixel dimensions, measuring the printed width, and dividing, then repeating for every placement on every page. Scaled, rotated or reused artwork slows that arithmetic further, and overlooking a single small one is enough to spoil a run.

Where ProofSlip lands

Every placement measured, the coarsest at the top.

ProofSlip follows each image to wherever it is drawn, through nested forms and printable annotations, and computes pixels per inch from the space it occupies. Color and grayscale images fail below 150 ppi and warn below 300; 1-bit graphics such as scanned line art fail below 300 and warn below 600. The Images table sorts coarsest first, and selecting a row reveals pixel size, filters and each placement.

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 photo cropped and enlarged in layout

A designer places a 1,200-pixel-wide photo and enlarges it until the whole image would span 15 inches, so that only the face shows inside a 6-inch panel on a flyer. At fit-to-window zoom it looks fine.

ProofSlip measures the image at its placed scale, 1,200 pixels over 15 inches, and reports 80 ppi with a FAIL under rule I-01. The designer places the original camera file instead and checks the new export.

A scanned signature as line art

A form includes a signature that was scanned as a 1-bit image at 200 ppi and placed at its original size, next to body text that prints crisply.

One-bit images have hard edges and need more pixels than photos, so ProofSlip judges it against the line-art limit and fails it under rule I-03 at 200 ppi, naming the page it sits on.

One texture used on every page

A booklet repeats the same background texture on every page, placed larger on the cover than on the inside pages, and the designer wants to know which uses hold up.

ProofSlip records each placement separately and judges the image by its lowest effective ppi. The Detail pane lists every page with its own ppi, so it is clear that only the cover enlargement is too coarse.

Deep dive

What ProofSlip measures for each image, and what it leaves out

Pixels and placement. An image inside a PDF is stored once, with a width and height in pixels. Each time a page draws it, a transformation matrix scales it to a size on the page. ProofSlip reads that matrix for every placement, turns the placed width and height into inches, and divides the pixel counts by them. The smaller of the two results is the effective ppi it reports, so an image stretched more in one direction is judged by its weaker side.

Rounding and limits. The figure is rounded to a whole number before it is compared with a limit, so the number on screen and the severity always agree. Color and grayscale images count as continuous tone: under 150 ppi is a FAIL, and 150 to 299 is a WARN. Images stored at 1 bit per pixel, image masks, and images compressed with fax or JBIG2 encoding count as bitmap line art: under 300 is a FAIL, and 300 to 599 is a WARN. The limits are fixed in this version. If your printer asks for 300 ppi on photos, treat every image WARN as a failure for that job.

Where it looks. Images placed directly on a page, inside reusable forms, inside forms nested within forms up to 32 levels deep, inside printable annotation appearances, and inline images written into the page content are all measured. Placements too small to measure, images inside tiling patterns, and anything past the nesting limit are counted in an INFO note rather than guessed at.

What the number does not tell you. Effective ppi is about pixel density only. ProofSlip does not decode image data, so it cannot judge JPEG compression, blur or noise, and it does not evaluate the resolution of soft masks. A photo that was upscaled before it was placed can show a healthy ppi and still look soft, because enlarging pixels in an editor adds no detail. Compression filters are reported by name, such as JPEG or JPEG 2000, with no claim about quality.

Reading the Detail pane. Select an image row to see its object number, pixel size and bit depth, color, filters, whether it has a soft mask, its category, and every placement with its page, placed size in millimeters, and ppi in each direction. In a long document, that list is the quickest way to find the one oversized placement.

Raising a low figure. ProofSlip does not resample or replace images. Place a larger original, or print the image smaller, then export a new PDF and open it again. 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 the resolution of images in a PDF?

Find each image's pixel size and the size it is printed at, then divide pixels by inches. Doing that by hand means opening the source images and measuring the layout. In ProofSlip, choose Open PDF and read the Images table: each image shows its pixels, placed size in millimeters and effective ppi, lowest first. Select a row to see every placement when the same image is used more than once.

What ppi does an image need for print?

Your printer sets the figure that counts, usually on its spec sheet, and it can differ by product: a banner seen from across a room needs less than a business card held in the hand. ProofSlip applies fixed limits in this version. Color and grayscale images fail below 150 ppi and warn below 300; 1-bit line art fails below 300 and warns below 600.

Why does my image say 72 ppi in an editor but more in ProofSlip?

The ppi stored in an image file is a tag that suggests a print size, and it changes nothing about the pixels. ProofSlip ignores that tag and divides the real pixel count by the size the image occupies on the PDF page. A 3,000-pixel-wide image tagged 72 ppi and placed 5 inches wide is 600 effective ppi, which is why the two numbers disagree.

Can I change the limits, for example to require 300 ppi?

Not in this version. ProofSlip uses fixed limits: color and grayscale images fail below 150 ppi and warn below 300, 1-bit images fail below 300 and warn below 600, and bleed under 3 mm is a warning. Compare them with your printer's or your shop's spec sheet. Where the spec is stricter, treat the matching WARN rows as failures for that job; the effective ppi of every image is listed, so the comparison takes a glance.

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. Trim, bleed and page size, read from the file itself. Every font in the PDF, and whether it is embedded.

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