CHROMiX

Press Profiling and number of patches

I have a question about a profiling run we are going to be doing in a couple of weeks. First a little background in case it helps, we have one sheetfed Heidelberg press, print using G7 process, doing a new calibration\profiling run after everything being reset on press and new inks being used, I use Profilemaker and plan on doing a profile run also just to see if I get a better proofing result using a custom profile instead of just using the standard Gracol profile in the proofer also.

Anyway, my question is as far as number of patches go when profiling, is more always better? I ran across the larger targets that Bill Atkinson has on his sight, the biggest having 6,048 patches! I could use this for a proofer profile but don’t have room for it in one pass on our 1/2-sheet size press. So would it be beneficial to make 2 press runs to get all this 6k patch target or just use the smaller one that will fit on our sheet size which is 4k patches. When you compare the ECI target I’ve used in the past with 1700 patches, these just seem to have so much more to measure, but will the profiles be that much better or does Profilemaker make better profiles with more patches?

Any and all thoughts appreciated,
Thanks
Terry

I wouldn’t recommend splitting the target between two press runs… you’d be better off having all patches represented inclusivley on one sheet. Press conditions can change between runs and you would not have one or the other halves represented on a given run.

As far as the number of patches to include, the eci or it874 targets will do a decent job on an offset press, though they could perhaps use more patches near the gray axis… A larger patch count might result in a slightly more accurate profile, but has the potential to result in banding. Besides, extra profile accuracy in a device as variable as an offset press might not have value that is truly realized and just serve to increase measurement time. I think you’d do well simply using th it874 or a more reasonable sized yet larger patch count target and weighted averaging throughout the run.

Also, not sure if Atkinson’s targets are randomly ordered, but this is desirable for offset press profiling.

Mike

-----Original Message-----
From: prepper
To: PressProfilingForum@colorforums.com PressProfilingForum@colorforums.com
Sent: Sat Dec 27 14:29:50 2008
Subject: Press Profiling and number of patches

I have a question about a profiling run we are going to be doing in a couple of weeks. First a little background in case it helps, we have one sheetfed Heidelberg press, print using G7 process, doing a new calibrationprofiling run after everything being reset on press and new inks being used, I use Profilemaker and plan on doing a profile run also just to see if I get a better proofing result using a custom profile instead of just using the standard Gracol profile in the proofer also.

Anyway, my question is as far as number of patches go when profiling, is more always better? I ran across the larger targets that Bill Atkinson has on his sight, the biggest having 6,048 patches! I could use this for a proofer profile but don’t have room for it in one pass on our 1/2-sheet size press. So would it be beneficial to make 2 press runs to get all this 6k patch target or just use the smaller one that will fit on our sheet size which is 4k patches. When you compare the ECI target I’ve used in the past with 1700 patches, these just seem to have so much more to measure, but will the profiles be that much better or does Profilemaker make better profiles with more patches?

Any and all thoughts appreciated,
Thanks
Terry

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