gizmobench

Document Scanner

Take a photo of a page with the camera, or choose photos you already have, then drag four handles onto the corners of the paper. The tool maps those corners onto the corners of an A4, Letter, Legal or A5 page, or of a page shaped by the corners themselves, so a sheet shot at an angle comes out square instead of as a trapezoid, and then applies one contrast curve in greyscale or colour. You see the photo and the finished scan together, put the pages in order, and download them as JPGs or as one PDF. It all happens in this browser tab, so photos and camera frames are never uploaded, and an outline whose corners cross, dent inward or fall on one line is refused with the reason rather than warped into something unreadable.

Straighten a photo of a page

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or drop photos anywhere on the stage. The camera asks your permission first.

Never uploadedNo accountFour-corner correctionJPG or PDF
Pages
none yet
Page size
A4
Corners
not placed
Contrast
1.4, greyscale
Page
Orientation
Resolution
Colour
1.4
Edge trim

A4 is 210 by 297 mm. Drag a corner, or focus it with Tab and nudge it with the arrow keys; Shift moves it ten times further. An edge trim cuts that percentage of the page off every side and scales the rest up to fill it.

  • Corners on the photo's own corners1000 x 800 photo, output 1000 x 800
    every pixel stays where it was
  • Trapezoid (100, 0) (300, 0) (400, 200) (0, 200)to a 400 x 200 page
    corners land on (0, 0) (400, 0) (400, 200) (0, 200)
  • Corners that cross or line uptop right and bottom right swapped
    refused: move a corner, nothing is warped
Your photos stay on this device. The four corners you place land exactly on the corners of the page you choose, or just beyond them by the edge trim you set, and the pixels between are resampled, so very fine print can soften; contrast is one fixed curve, (value - 128) times your setting plus 128, applied to each colour channel or to the grey. It does no OCR and cannot recover text that is blurred, in shadow or outside the photo, and corners that cross, dent inward or fall on one line are refused rather than warped. Photos over 16 megapixels are scaled down to 16 megapixels before correction, a JPEG, PNG, WebP, GIF or BMP file whose header states more than 120 megapixels is refused before it is decoded, and photos and camera frames are processed on your device and never uploaded. Up to 50 pages a document. The only things this page remembers between visits are the six scan settings above.

Common questions

How do I scan a document with my phone camera?
Press Use camera. The camera opens only once your browser has your permission, and the page asks for the back camera where the device has one. Fit the whole sheet in the picture and press Take photo: that frame becomes a page, and the camera stays on for the next page until you press Close camera. Nothing is recorded between presses. Then drag each page's four corners onto the paper and press Download PDF. If the camera is blocked or missing, the page says why, and Choose photos still works: on most phones the photo picker also offers the phone's own camera app.
How do I straighten a photo of a document taken at an angle?
Drag the four numbered handles onto the corners of the paper, going clockwise from the top left: 1 top left, 2 top right, 3 bottom right, 4 bottom left. With a mouse you can also click on the photo to bring the nearest corner there. From the keyboard, Tab to a handle and use the arrow keys, which move it a quarter of a percent of the photo's long side, or ten times that with Shift. The tool then maps those four points onto the corners of the page and fills everything between with a perspective correction, so a trapezoid becomes a rectangle. Rotate page turns the finished page a quarter turn clockwise for a photo taken sideways, Whole photo puts the corners on the photo's own corners, and Reset corners starts again.
Can I save several pages as one PDF, or as JPG files?
Yes. Every photo becomes a page in the list below the stage, where the up and down buttons set the order and the cross removes one. Download PDF writes all of them in that order, one scan filling each page: A4 pages are 595.28 by 841.89 points, Letter 612 by 792, Legal 612 by 1008 and A5 419.53 by 595.28. The JPG button saves a single page as scan.jpg, or several as a zip of scan-01.jpg, scan-02.jpg and so on, in the same order. Each page can also be saved on its own from the link under its scan.
What does the contrast setting do to my scan?
It applies one curve to every pixel: (value - 128) times your setting plus 128, rounded and held between 0 and 255. At the default 1.4, a paper grey of 200 becomes 229 and an ink grey of 60 becomes 33, so the page gets lighter and the writing darker; at 1.0 the curve leaves every level as it is, and the slider goes up to 3.0. In Greyscale each pixel is first turned into one grey level from its red, green and blue using the Rec. 601 weights (0.299, 0.587 and 0.114), then the curve is applied; in Colour the curve is applied to each channel. It is the same curve everywhere on the page, so a shadow across the sheet stays darker than the rest rather than being cleaned away.
Which page sizes and resolutions can I choose?
A4, Letter, Legal and A5, portrait or landscape, at 150, 200 or 300 dots per inch. An A4 scan is 1240 by 1754 pixels at 150 dpi, 1654 by 2339 at 200 and 2480 by 3508 at 300. Match gives a receipt or a card its own shape: the page takes the longer of each pair of opposite edges the corners measure in the photo, held to 16 megapixels, and the PDF page is that many pixels at the resolution you choose. Because the photo was taken at an angle, those measured proportions can differ a little from the real sheet's.
Does the scanner read the text in my document?
No. It straightens and adjusts the picture only, so the scan and the PDF hold an image of the page, and text in them cannot be selected or searched. It also cannot bring back words that are blurred, in deep shadow or cut off at the edge of the photo. To turn printed English from a picture into editable text, save the page as a JPG and open it in the Image to Word tool.
Are my documents uploaded anywhere?
No. Photos are decoded by this browser, straightened on a canvas in this tab, and the JPGs, the zip and the PDF are all written here too. The PDF and zip writers are loaded from this site, and from nowhere else, the first time you ask for one of those downloads. The only things remembered between visits are the six scan settings: page size, orientation, resolution, colour, contrast and edge trim. Photos, corners and scans are gone when you close the tab.
Why were my corners refused, and are there any limits?
The outline has to look like a page before anything is warped: every corner inside the photo, no two on the same spot, no three on one straight line, no edges crossing, no corner pointing inward, and the four going clockwise, because anticlockwise would mirror the page. Each rule has its own message saying what to move. As for limits, a document holds up to 50 pages, and a photo over 16 megapixels is scaled down to 16 megapixels, shape kept, before it is straightened, which is close to the largest canvas some phone browsers will draw and still more pixels than an A4 page at 300 dpi needs. A JPEG, PNG, WebP, GIF or BMP file whose header states more than 120 megapixels is refused before it is decoded, with the size it states in the message, because the browser would have to hold the whole photo in memory at 4 bytes a pixel. A photo in any other format, such as HEIC or AVIF, or one whose header gives no size, is refused as well, because its size cannot be checked before it is decoded: save it as a JPEG and add that.

The four corners you place land exactly on the corners of the page you choose, or just beyond them by the edge trim you set, and the pixels between are resampled, so very fine print can soften; contrast is one fixed curve, (value - 128) times your setting plus 128, applied to each colour channel or to the grey. It does no OCR and cannot recover text that is blurred, in shadow or outside the photo, and corners that cross, dent inward or fall on one line are refused rather than warped. Photos over 16 megapixels are scaled down to 16 megapixels before correction, a JPEG, PNG, WebP, GIF or BMP file whose header states more than 120 megapixels is refused before it is decoded, and photos and camera frames are processed on your device and never uploaded.