Occasionally someone wants to know the dot gain of a CMYK output device, but they lack the density measurements needed by the Murray-Davies equation. All they have is Lab measurements. I have prepared two Excel spreadsheets that estimate the dot gain from the Lab measurements of sets of CMYK colors. They are available here as downloads:
|File Name||File Size||Description|
|LabDotGainCalculator1.sit||17K||Nine patches. Calculates dot gain at 50% points only.|
|LabDotGainCalculator1.zip||13K||Nine patches. Calculates dot gain at 50% points only.|
|LabDotGainCalculator2.sit||66K||84 patches. Calculates dot gain at 0%, 5%, 10%, …, 95%, 100%. Includes graphs.|
|LabDotGainCalculator2.zip||60K||84 patches. Calculates dot gain at 0%, 5%, 10%, …, 95%, 100%. Includes graphs.|
The method I use is documented here.
If you are working from a CMYK ICC device profile, you can obtain the necessary Lab values from the profile using Photoshop.