How do I photograph a document so it is easy to read?

A phone photo can replace a scanner

If you have no scanner, you photograph invoices, letters and forms with your phone. The camera in a current phone resolves fine enough to show an A4 page legibly. What makes a photo unusable is hardly ever the resolution. It is shadows, glare, holding the phone at an angle and a page that barely stands out from the surface it lies on. All four can be fixed before you press the shutter, and that takes less time than a second attempt.

Even light without shadows

The best light is bright daylight near a window, but out of direct sun. Direct light casts hard shadows and makes glossy paper reflect. In the evening a lamp shining onto the sheet at an angle from the side takes the place of daylight. The flash is usually the worse choice, because it leaves a bright spot in the middle of the sheet in which the text disappears.

The most common shadow is your own. If you stand between the lamp and the sheet, your head and the phone fall onto the page as a dark patch. Turn so that the light comes from the side rather than from behind you.

A background that stands out from the paper

A white sheet on a white table has no visible edge. For the eye that is a small problem, for a program that has to find the edges of the page a big one. Put light paper on a dark surface of a single colour, such as a wooden table or a piece of dark card. A patterned surface gets in the way, because its lines can look like edges.

Straight above the sheet, with a little margin

Hold the phone as parallel to the sheet as you can and directly above it. The more the camera is tilted, the more the page turns into a trapezoid in the photo, and the more a program has to correct it later. That works, but the half of the page further away loses sharpness in the process.

The whole page belongs in the picture, with a narrow margin all round. A corner that is cut off cannot be added later, and with a corner missing no software can straighten the page reliably. Tap the middle of the sheet before you take the photo, so that the camera focuses there. Press a curved page, for example from a bound booklet, as flat as you can without putting your fingers on the text.

What a program can still correct

A photo taken at a slight angle is no reason to take another one. Document programs find the four corners of the page and transform the image back into a straight rectangle. This correction has limits, though. It cannot fix blur, glare over the text or a corner that is cut off. With very little contrast to the background, or with strongly curved pages, detection does not always find the corners correctly either, and then you set them by hand.

If you want to search the text of the page later, the care pays off twice. OCR reads a sharp, evenly lit photo far more reliably than one with a shadow across a line.

Where Quorvyn Docyra helps

Quorvyn Docyra is meant for the step after the photo. You transfer the picture from your phone to your computer and import it there. Docyra looks for the four corners of the page and straightens it. If a corner is off, you drag it to the edge of the sheet with the mouse. If a photo looks blurred, too dark, skewed, cut off or covered by glare, Docyra points this out and says how a new photo will turn out better. All of this is free and runs on your computer, without the picture being uploaded. Docyra is still in development and not available yet. The product page lists the systems it is planned for and what it deliberately does not do.