Before you consider purchasing an expensive colorimeter to use to match colors, check your computing equipment. You might be able to use your document scanner as a colorimeter. The following are reasons why this can work:

  1. A scanner is cheap, and you may already have one.
  2. The device already accurately scans photographs and other printed material.
  3. The scanner contains a standard light source, eliminating the need to calibrate for the light source used for the measurement.
  4. A scanner is already calibrated for proper color balance. There is no need to make any adjustments for this.
  5. The RGB content of the object is easily obtained from the scanned image.
  6. Multiple colors on the same object can be analyzed with the same scan.

There are a few things to watch for with this method:

  1. Be careful to use a lossless file format (e.g. .bmp), rather than any lossy format (e.g. .gif, .jpg).
  2. Make sure the transfer from the scanner to the file is not managed by any color management system except the calibration settings.
  3. Some objects might be hard to scan (e.g. a car fender).
  4. Some pigments produce faulty RGB scans. The wrong color is produced in the file.
  5. Some scanners have the equivalent of the "automatic tint control" found on older color TV sets. It sacrifices greens and magentas to provide better tones for human faces. This can be corrected with an art or photo editor. Or the readings can be used as they are.

The Procedure:

  1. Place the object to be analyzed on the scanner.
  2. If the object is bulky enough that the cover won't close, make a mask out of black construction paper so only the part against the scanner will be scanned.
  3. Scan the object at the highest resolution and 24 bit color.
  4. Save the file in a lossless format.
  5. Open the file in any program that lets you see the RGB values. One such possibility is Corel Photo-Paint.
  6. Use the tool that lets you see the RGB values. In Corel Photo-Paint, the tool is the eyedropper color picker.
  7. All colors analyzed with the same scanner can be directly compared.
  8. The R (red), G (green), and B (blue) values will each be a number from 0 to 255. A higher number indicates that the object reflects more of that color.

Excel can be used to analyze the various colors.