Adjustments to the RIP....

Disappointed

Well-known member
We have a Harlequin Rip, and it is doing odd things with the export data from our press-sign software, here's the scenario...

Create a linear tone curve, set 60% at the 50% point on any curve, extrapolate the rest of the curve and save.

Edit the curve from calibrated and enter 45% at the 50% point, extrapolate and save.

This i would presume would give a net result of 55% at the 50% point????

Why do we get 52.86% ???

Its baffling me but will answer a lot of problems we have been seeing when feeding back adjustments from press sign.

Thanks

Dave
 
Try entering the desired percentage you want on the plate using "edit uncalibrated" instead of "Edit calibrated"...meaning if you want to see 55% on the plate at midtone, choose "edit uncalibrated", clear your previous values and enter 55% at the 50% tone and (if desired) extrapolate the rest. For plate curves, I've always used tone curves by themselves, and always entered the values I expect to measure with my plate reader. There are other ways to compensate using Press curves, etc, but its often invisible what value is actually being sent to the plate setter, and I like to know, so I use tone curves by themselves.
 
Hi Meddington,

i do always start off with a new curve then enter the data into edit-uncalibrated. I can also do the first fine adjustment that way but it gets really tricky when the values have been fine tuned and you just want say another half percent but spread out over maybe 20-60% range, then it gets really awkward doing the maths. It would be easier to use the edit-calibrated as it always starts on a fresh curve so you can see exactly what you are doing, but it does not do what i expect it to do.

Dave
 
If you are entering 60% in the 50% screen in your first calibration set, the RIP will adjust so it will say you are reading 60%, lets lower that down so now where you see a 50% dot the RIP would think it needs to print around a 40% or so in order to get you at the desired 50%.

Now if you edit from calibrated and enter 45% in the 50%, you just to the RIP that when you output a calibrated target the 50% reads 45%. This means the RIP is going to try and bump up the calibration around 5% so it would adjust up from 50%. That is why you are getting 52.86%.

Calibration is one of the most complicated parts of printing. You only want to use the edit from calibrated button if you are taking readings from a calibrated target. So if you reading an uncalibrated target you would not use the edit from calibrated button.

I would recommend starting over an print an uncalibrated target. From this target, create a new calibration in the calibration manager. Then apply it in your page setup and print a new CALIBRATED target. Take readings from this. If the values appear to be off then go in and EDIT FROM CALIBRATED and enter the values you are reading from the calibrated target. Next, save the calibration and print a new calibrated target. The values should be correct. If they are not, then you may want to check your exposure setting on your output device as it may be incorrect.
 

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