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How to scan a document without a scanner
The camera is not your problem. A page-filling shot from an ordinary phone carries more detail than most office flatbeds capture at their default setting. What ruins it is the light you shoot in, the angle you hold, and the flash you should not have used.
The short answer. Fill the frame with the page, shoot with light coming from in front of you, and keep the flash off. A page-filling photo from a 12 MP camera works out to roughly 340 DPI across a Letter sheet — comfortably above the 300 DPI most agencies ask for.
The arithmetic, so you can check it yourself
DPI is not a setting on a camera. It is pixels divided by inches. A US Letter page is 8.5 × 11 inches, so at 300 DPI you need 2550 × 3300 pixels — that is 8.4 megapixels.
| Camera | Pixels on a page-filling shot | DPI across a Letter page |
|---|---|---|
| 8 MP | ≈ 2450 × 3260 | ≈ 288 DPI |
| 12 MP | ≈ 3000 × 4000 | ≈ 353 DPI |
| 48 MP | ≈ 6000 × 8000 | ≈ 706 DPI |
Those numbers assume the page fills the frame. That is the whole catch. Shoot the same page from across a desk so it covers a third of the frame, and you keep a ninth of the pixels — a 12 MP camera drops to about 118 DPI, and no software can put the detail back.
The four things that actually go wrong
1. Your own shadow
You lean over the page to line up the shot, and your head and shoulders block the ceiling light. The shadow lands exactly where you are photographing. Put the page next to a window and stand so the light arrives from in front of you, not from behind your back.
2. The flash
A flash fires from a few inches away and lands as a hot circle on the paper. Inside that circle the sensor clips: every pixel reads maximum brightness, so there is no difference left between the ink and the paper. A shadow can be corrected because the letters are still there, only darker. A blown highlight cannot, because nothing was recorded. If a page has a flash hotspot across the text, take it again without flash.
3. The angle
Holding the phone at a tilt turns the rectangle into a trapezoid, and the far edge of the page ends up with fewer pixels per inch than the near edge. Perspective correction straightens this, but it works from the pixels you captured — the far edge stays the softest part. Shoot from directly above where you can.
4. Cropping in the gallery afterwards
Cropping a photo in the phone gallery keeps the pixels but usually re-saves the JPEG, and each re-save costs a little detail on the thin strokes. Crop once, at the end, not repeatedly.
The order that works
- Flat surface, page next to a window, light from in front.
- Phone parallel to the page, page filling the frame, flash off.
- Tap the screen on the text so the camera exposes for the paper.
- Straighten the angle, even out the lighting, then export at the size the portal asks for.
The last step is the one people skip, and it is the one the portal checks.
Turn a phone photo into a straight, evenly lit, 300 DPI file
Runs in your browser. Your document is never uploaded. First one is free.
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