Auto-crop got it wrong? Here’s how to fix it fast

Edge detection is very good and still not psychic. Low contrast, clutter and folds can fool any scanner. The design goal in ToPDF is different from “never wrong”: it's never silently wrong — uncertain detections are shown to you before they become a bad crop.

The 10-second fix

1. If the result is already on screen with a bad crop, tap Adjust crop.
2. Drag the corners onto the paper's true corners — the magnifier loupe shows exactly where you are.
3. Tap Apply crop. The page is re-straightened and re-enhanced from the original photo, so nothing was lost in between.

Why crops go wrong

• White-on-white: paper on a pale table gives edges nothing to grip. Fix: darker background.
• Clutter: other papers, cables or a keyboard next to the page offer competing rectangles. Fix: clear 10 cm around the document.
• Folds and creases: a sharp fold can read as the page's edge. Fix: flatten, or expect a visit to the editor.
• Partial page in frame: if a corner is cut off in the photo, no software can restore it. Re-shoot with margins.

Meet the editor halfway

When ToPDF isn't confident, it opens the corner editor pre-filled with its best guess — most “failures” are two corners already correct and two needing a nudge. That confirmation step exists precisely because a confident-looking wrong crop (the top of a form sliced off, an ID's MRZ clipped) is the worst outcome a scanner can produce.

Frequently asked questions

Will re-cropping degrade the image?

No — every Apply re-derives the page from your original photo, not from the previous crop.

The scanner keeps cropping a sub-region (like the photo on my ID). Why?

High-contrast inner rectangles can attract detectors. ToPDF has containment rules against this, but if it happens, one visit to Adjust crop fixes it — drag corners to the card’s real edges.

Can I turn auto-crop off?

Practically, yes: open Adjust crop and place the corners at the photo’s extremes to keep everything, or crop any region you want manually.