Color Management & Quality Control
Color Management & Quality Control
- Subject: Color Management & Quality Control
- From: Kevin Muldoon <email@hidden>
- Date: Thu, 6 Jan 2005 15:29:46 -0500
When has the color output of your Ink-Jet printer drifted too far? How do you check to see if you've drifted at all? What is an acceptable tolerance level for 'too far'? In other words, I'm talking about maintaining consistent color on output devices and this requires quality control procedures.
I plan to implement a color QC procedure for our HP5500ps driven by ONYX Rips. I am very close to finalizing this with a step by step instruction on what to do when the color has drifted too far.
The QC procedure is essentially this... I have noted the LAB values of 8 rich gray patches for each media, these values being captured by a spectrophotometer just as soon as the media is profiled. The user would print these 8 patches every day (3 times a day, hourly, whatever) to specific media to determine the Delta-E value from the target LAB values. If the greyscale patches exceeds Delta-E of (insert value here), then re-linerization would be required to bring the printer back into known values. Sounds good, right?
Problem...
Humidity causes profound shifts in color. If a profile is created when relative humidity is 36% on a bond stock, I am unable to bring the patches back into <2Delta E when the humidity is over 85% even after relinerizing and creating new Media Model (grey ramp). So, should I say relin after if values exceed 3 Delta? 4 Delta? More? Would you use a gray ramp to test your color drift or would you prefer to measure CMYK patches?
Thank you for your time and sharing what experiences you have on this subject.
Kevin Muldoon
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