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Graphic Design/Web Design

Calibrating a laser printer to reproduce halftones

This is an exercise to measure the ability of a Postscript laser printer to reproduce halftone dots, and adjust images to print a smooth spectrum of gray values.

Download the TIFF file of this test image.

How to proceed
1. Download the TIFF version of the test file. Print it to the laser printer as a "before" example.

2. Using a loupe or magnifying glass, examine the grayscale. Locate the point on the scale where you see the light dots become inconsistent and mark that point. Estimate the percentage value at that point, the smallest printable dot.

3. Convert your "0 to 100" percentages to the "255 to 0" levels numbers of the 8-bit grayscale.

4. Locate the point on the scale where you see the tiny white dots in the dark area become plugged and mark that point. Estimate the percentage value at that point, the darkest halftone to contain a printable dot.

5. Use the Levels adjustment or a Levels Adjustment Layer to change the Output values. Set the black value from pure black to a dark gray to your observed value. Set the white value from pure white to your observed value.

6. Print the file again and check the light and dark areas to determine if the changes were successful in creating printable dots from black to white.

7. Write your name and the Output values on the "After" print; staple the two together and hand them in.

 

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