| 摘要 |
<p>A method 100 maximizes the contrast between light and dark markings 13 that carry information. The markings are illuminated by a variable output light source 16, and a reflected image is received by a detector 18 and processed by a controller 20. The method calculates a histogram of the reflected image at step 102, and the method determines at step 104 if the histogram has one peak or two peaks. The method increases at step 110 or decreases at step 112 the output of the light source 16 by adding or subtracting a small step amount to or from the current light level of the light source 16. The method 100 is a continuously repeating loop, and the method increases or decreases the light level of the source of illumination with substantially every loop to oscillate about an equilibrium light level that provides maximum contrast.</p> |
