A photograph of a document is recognisably a photograph — grey paper, uneven lighting, a visible desk edge. Offices notice, and some reject it. This adjusts contrast, brightness and the white point so the paper comes out white and the text comes out black, which is what makes it read as a scan.
Your images never leave your device. They are read and processed by your browser and written into a PDF in memory. Nothing is uploaded.
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Result
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What the Photo to Scanned PDF does
Three processing modes cover the useful range. Greyscale removes the colour cast that makes paper look grey. High contrast additionally forces near-white to pure white and near-black to pure black, which produces the crispest text and the smallest files. Colour keeps everything, for documents where the colour matters.
What no browser tool can do is correct perspective — a page photographed at an angle stays trapezoidal. Photograph square-on and the rest of the processing does its job.
How to use this tool
- Photograph each page square-on in even light, with the page filling the frame. Avoid shadows across the paper.
- Add the photos and check the page order.
- Start with greyscale. Switch to high contrast if the paper still looks grey.
- Raise contrast if text is faint; lower the white point if the background is still not white.
- Press Create scanned PDF and check the result before submitting.
What the processing does
1. GREYSCALE — remove the colour cast
L = 0.299 R + 0.587 G + 0.114 B
2. CONTRAST — separate ink from paper
factor f = (259 × (C + 255)) ÷ (255 × (259 − C))
new = f × (old − 128) + 128 + brightness
3. WHITE / BLACK POINT (high contrast mode only)
luminance above the white point → pure white
luminance below the black point → pure black
midtones left alone, which keeps text edges readable
Worked example
Example: three phone photos of a letter
| Before | grey paper, warm cast, 2.8 MB each |
| Mode | greyscale, contrast 40, brightness 6 |
| After | 3-page A4 PDF, white paper, about 700 KB |
The file is much smaller as well as cleaner, because greyscale and higher contrast compress far better than a colour photograph.
What your result means
Greyscale suits most documents. High contrast is better for plain printed text and produces the smallest files, but it can lose faint stamps and light pencil marks.
If the paper is still grey, lower the white point in high contrast mode — anything lighter than that value becomes pure white.
If text has broken up, the black point is too high or contrast too strong. Reduce both.
Important considerations
- Lighting matters more than any setting. Even daylight near a window, with no shadow across the page, gives the best starting point.
- Photograph square-on. Perspective distortion cannot be corrected here and looks obviously wrong on a document.
- High contrast mode can erase faint official stamps or light ink. Check the result before using it on anything important.
- For a document that will be read by OCR, high contrast usually improves recognition accuracy.
- Colour mode is right for documents where a coloured seal, signature or highlighting carries meaning.
Limitations of this tool
- Images are capped at 2400–3000 pixels on the longest side to keep memory use manageable on phones.
- Photographs are embedded as JPEG, so PNG transparency is flattened onto white.
- Perspective distortion cannot be corrected — photograph the page square-on for the best result.
- Perspective and skew correction are not available — the page must be photographed square-on.
- Automatic edge detection and cropping are not included; crop the photographs first if needed.
Frequently asked questions
How do I make a phone photo look like a scan?
Photograph square-on in even light, then use greyscale with contrast around 40. If the paper still looks grey, switch to high contrast and lower the white point until the background goes pure white.
Why does my document look slanted?
Because it was photographed at an angle. Perspective correction is not possible here — retake the photograph directly above the page, with the camera parallel to it.
Which mode should I use?
Greyscale for most documents. High contrast for plain printed text where you want the smallest, sharpest file. Colour when a seal, stamp or highlighting matters.
Why did my stamp disappear?
High contrast mode forces light pixels to white, which can erase a faint stamp. Use greyscale or colour mode instead.