# Straighten document photo

> Correct document perspective using four corners you supply.

[Open tool](https://www.toolcabana.com/tk/document-unwarp) · [PDF and documents](https://www.toolcabana.com/tk/category/pdf-and-documents)

Tool ID: document-unwarp. Requested language: tk. Description language: en. Complete guide translation: no; untranslated sections use English.

## Overview (en)

Straighten document photo corrects the perspective of a photographed page using four corner points you supply. Enter the corners in source-image pixels as JSON, in top-left, top-right, bottom-right, bottom-left order, and the tool maps that area to a flat rectangle saved as document-flat.png. It corrects perspective only, not curved or bent pages.

## Supported tasks (en)

Enter four document corners in source pixels, ordered top-left, top-right, bottom-right, bottom-left. Applies a browser perspective transform; curved-page dewarping is not supported.

## Steps (en)

1. Choose a source file. If the tool accepts multiple files, arrange them in the order you want.
2. Set four corners in source pixels: top-left, top-right, bottom-right, bottom-left (json [[x,y],...]).
3. Run straighten document photo, review the output, then use the available copy or download controls.

## Settings

- Four corners in source pixels: top-left, top-right, bottom-right, bottom-left (JSON \[\[x,y\],...\]) (en; key: corners; type: textarea)

## Limitations (en)

Image inputs: up to 32 megapixels, batches up to 10 images. Audio/video uploads: 50 MB; transcription: 120 seconds. Edited videos: 20 seconds, 4 fps and 640 pixels wide. Translation: English/Spanish, 30,000 characters; subtitles: 200 cues. Neural speech: 1,000 English characters. Model downloads and memory requirements vary by device.

## Example input

```text
A useful tool makes everyday work easier. Review the results before sharing.
```

## Privacy and connections (en)

Processes source in your browser. Copy and download are explicit actions; source is not saved to account history.

## Questions (en)

### How do I enter the corners to straighten a document photo?

Use a JSON array of four [x,y] pairs in source pixels, ordered top-left, top-right, bottom-right, bottom-left, for example [[40,60],[900,50],[920,1250],[30,1240]]. Every corner must lie inside the image.

### Can it flatten a curved book page?

No. The tool applies a perspective transform between four corners, which fixes a flat page photographed at an angle. Pages that bend or curve, such as open book spreads, are not dewarped.

### How big is the straightened image?

Width and height come from the longer of each pair of opposite edges you marked. The corrected area must be under 8 megapixels, and corners forming a degenerate shape are rejected.

### Where is my input processed?

Processes source in your browser. Copy and download are explicit actions; source is not saved to account history.

### What are the input limits?

Image inputs: up to 32 megapixels, batches up to 10 images. Audio/video uploads: 50 MB; transcription: 120 seconds. Edited videos: 20 seconds, 4 fps and 640 pixels wide. Translation: English/Spanish, 30,000 characters; subtitles: 200 cues. Neural speech: 1,000 English characters. Model downloads and memory requirements vary by device.

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