How to photograph rice for the scanner

A two-minute setup. Get these right and the scanner becomes a measuring tool rather than a guess.

1. Take a fair sample

Mix the lot first, then take your sample from several places (or split it down by quartering). About 200–300 kernels — roughly a level teaspoon of milled long-grain rice — gives stable percentages. With fewer than 100 kernels, a handful of broken grains can move the result by several points.

2. Use a matte black background

White rice is easiest to separate from a dark, non-shiny surface: black card, black cloth, a black mouse mat. Avoid white paper (too little contrast), glossy surfaces (reflections look like grains) and patterned cloth.

3. Spread the grains so none touch

Touching grains merge into one shape, so the scanner excludes them and tells you how many it skipped. Slide grains apart with a card edge. Leave a margin around the photo edge: kernels cut off by the frame are not counted.

4. Add a coin for millimetres

Lay one coin flat, a little away from the grains, and choose it in the scanner settings. The scanner finds the coin automatically and converts pixels to millimetres. Common choices:

Without a coin you still get broken %, length/width ratio and colour — just no millimetre sizes or the 1.4 mm chip rule.

5. Light it evenly

Daylight near a window (not direct sun) or two lamps from opposite sides works well. Avoid the phone flash — it creates glare spots and hard shadows. Keep your own shadow off the sample.

6. Hold the phone flat, directly above

• Keep the phone parallel to the table, about 20–30 cm up. Tilting makes far grains look shorter.
• Don't use digital zoom — move closer instead, then tap the screen to focus on the grains.
• Each grain should be at least ~40 pixels long in the photo. A normal phone photo of an A5-sized area is plenty.
• Use the same setup every time if you want to compare colour between samples.

7. For chalkiness: light the grains from behind

Chalky (opaque, floury) parts of a kernel block light, while translucent parts let it through. A normal top-lit photo can't reliably tell them apart — a backlit one can.

1. Put the grains on a lightbox, or on a tablet or phone screen showing a plain white image at full brightness (protect the screen with a clean clear sheet).
2. Dim the room and turn off overhead lights so light comes only from underneath.
3. Photograph from above as usual and choose Lightbox / backlit in the scanner.

Chalkiness is a beta measurement. Use the sensitivity slider in Advanced to match a few kernels you have judged by eye.

Common problems

Scan a rice sample →