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jstotz
08-16-2010, 03:46 PM
Can someone explain how ColorFlow handles adjustments to printing conditions? Assume a typical setup with a press set up to match the Gracol standard. I can see two scenarios and I was wondering how they can be addressed and if Colorflow made a distinction between them.

1. After profiling a press in Colorflow and running for a few weeks, we determine that one color is consistently gaining too much and needs a slightly different curve.

2. A job goes on press and the color doesn't match because of some transient issue with the press such as ink temperature, bad water control, slurring, blanket problem, etc. The immediate result is that the Cyan and Black are gaining too much. The cause may or not be known at the time, but it can only be addressed later, not while the job is running. For now we just need to make some new plates with a revised but temporary curve.

I'm assuming that press calibration in Colorflow is usually made with curves. Is this correct or does it use profiles?

david.herder
08-16-2010, 07:32 PM
1. After profiling a press in Colorflow and running for a few weeks, we determine that one color is consistently gaining too much and needs a slightly different curve.

2. A job goes on press and the color doesn't match because of some transient issue with the press such as ink temperature, bad water control, slurring, blanket problem, etc. The immediate result is that the Cyan and Black are gaining too much. The cause may or not be known at the time, but it can only be addressed later, not while the job is running. For now we just need to make some new plates with a revised but temporary curve.

I'm assuming that press calibration in Colorflow is usually made with curves. Is this correct or does it use profiles?

Hi Jamie,
Adjusting the device behaviour in the cases that you describe would be done with curves. In ColorFlow, this is done particularly by adjusting the Device Curves.

1. Most people follow the approach of adjusting the device curve to compensate for the consistent problem (in your example, gain increase). This gives you the immediate ability to correct for the device condition anomaly in a very timely manner. Another approach would be to recharacterize the press condition. Kind of like wiping the slate clean and starting over, involving much more time. Doing this really depends on your production bandwidth.

2. This case would definitely involve making a device curve edit, taking a snapshot, and outputting plates with the new snapshot. This way, your production workflow retains the old device curves in the Approved ColorFlow snapshot, while your transient issue is addressed by utilizing the newly captured device curve in the latest snapshot. Note: in versions of Prinergy 5.1.2.1 and earlier, the snapshot on output must match the snapshot used during refine. In 5.1.2.2, this constraint has been relaxed so that you do not have to re-refine your files to align snapshot numbers between refine and output processes.

regards,
dave

jstotz
09-23-2010, 08:06 PM
Thanks for that info. Here is a third scenario.

3. Customer decides that they don't like the proof and wants to make some correction that is too big to make using press ink moves. Therefore we need to make some number of plates over with different curves. Because these moves are not in response to a changing press condition, they need to be saved and used with the job the next time it prints.

In harmony, we would save a new curve and name it with the job number. It would stay in the harmony database until we needed it again. How would we handle this in ColorFlow?