benri-ni
Language: English

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Straighten a document photo

Line up the four corners of a document photographed at an angle and get a straight, rectangular image. Shadows on the paper can be whitened. Save as JPG or PNG.

Choose a photo → line up the markers with the corners of the paper → check the result and save. Your photo is not saved or sent.

or drop a file here

JPEG, PNG, WebP or other images this browser can show, up to 50 MB. You can also paste with Ctrl+V (⌘+V).

How the correction works

  • Line up the corners: place markers 1–4 on the top-left, top-right, bottom-right and bottom-left corners of the paper. Drag them, or select one and use the arrow keys (Shift moves 10 pixels), or type the coordinates. The corners are not detected automatically.
  • Straighten: the area inside the four corners is mapped onto a straight rectangle with a perspective transform. Each pixel of the result is interpolated from the four nearest pixels of the original photo.
  • Aspect ratio: “Estimate” uses the longer of the top and bottom edges as the width and the longer of the left and right edges as the height. Photos taken at an angle can be slightly off, so choose A4, Letter or a custom ratio when you know the paper size.

Whiten background

The tool estimates how bright the paper is in each area and divides by that brightness, which brings the paper back to white. Paper darkened by shadows or uneven light turns white, while thin lines stay because they are darker relative to the paper around them. “Strong” also turns light gray into white, so faint text or pencil lines may disappear. Black & white picks its threshold automatically from the brightness distribution.

What it cannot do

  • Flatten curved book pages, or restore missing or blurred text.
  • Recognize text (OCR).
  • Make a single PDF. Combine the saved images with “Images to PDF”.

Size and saving

  • Images up to 50 MB and 50,000,000 pixels can be loaded. Photos over 16,777,216 pixels are reduced, keeping their aspect ratio, before correction.
  • The result is limited to 8,192 pixels per side and 16,777,216 pixels; larger results are reduced, keeping their aspect ratio.
  • You can save as JPG (three quality levels) or PNG. Camera information such as location is not included in the saved image.
  • Your photo is processed on this device and is not saved or sent. Only the aspect ratio, background, color and format settings are stored on this device.

This tool processes your input and files on this device (in your browser) and does not send them to a server. See Privacy and ads for details.

  • Images to PDF

    Put JPEG, PNG, and WebP images into one PDF, one image per page. Choose A4 or Letter paper, orientation, margins, and whether to fit or crop each image.

  • Image resizer

    Convert JPEG, PNG and WebP images one at a time or in batches. Resize, adjust JPEG/WebP file size, and save successful results as a ZIP.

  • Make a solid background transparent

    Turn a white or single-color background transparent and save logos, signatures and line art as transparent PNGs. Choose the color, tolerance and area, and check what will be removed before saving.

  • HEIC to JPG converter

    Convert HEIC (HEIF) photos from an iPhone or other devices to JPG on this device and save them. The orientation stays as you see it, and location and other camera data are not included in the JPG.