CHROMiX

Interpretations of Graphs - (Neutral Behavior On Device)

I have supplied four charts from four of our CMYK presses I have calibrated and profiled in the last 5 or 6 months.
I’m trying to make better use of ColorThink and trying to figure how I can use it to quantify my profiles and calibration. I use Excel charts right now and they seem to work ok but I really prefer ColorThink’s visualization capabilities.

This is the exercise where I open the CMYK Neutral Test file in the stunt folder and then load a custom CMYK profile to determine how well calibrated the machine was at time of profiling. However I am not sure where the outer bounds of a quality calibration may be when looking at the ColorThink chart.

I was wondering if anyone could help tell me whether the plots of Neutral Behavior On a CMYK Device (not Neutral Behavior on Profile) would be considered within tolerance: As far as I could tell, each picture is oriented identically so there should be no visual skewing or anything like that.
home.hiwaay.net/~robrackn/color/150SC.jpg
home.hiwaay.net/~robrackn/color/3MEC.jpg
home.hiwaay.net/~robrackn/color/3MSC.jpg
home.hiwaay.net/~robrackn/color/IWEC.jpg

The CMYK profiles are very accurate based on all the PMS simulations I have to print out on these presses.

I assume these charts in this exercise would provide data detailing how hard each profile is having to work?

many thanks
Richard[/img]

Tolerance of any color should be determined mathematically and reported using Lab* Delta-E values.

Viewing it on a graph is helpful only if you’re wanting to visualize that Delta-E value. In addition, the Color Think graphing tool has no axis scales to refer to and you could not even quantify a plot if you wanted to.

First determine your target at each of those points and then calculate the Delta-E value. Compare that to your tolerance and then decide if your Neutral Behavior is acceptable.

Color difference calculator.

If I had to guess, I would say that you might be running your Solid Ink Density in Magenta a tad high, and are compensating in the 0% - 75% reigon with gain adjustments. When the open area starts to fill in and the ink goes solid, that trick doesn’t work anymore and you’re shifting the gray to Magenta. That’s just a guess based on your plots…

At 8:38 AM -0700 8/2/05, SonyDADC wrote:

Tolerance of any color should be determined mathematically and reported using Lab* Delta-E values.

Viewing it on a graph is helpful only if you’re wanting to visualize that Delta-E value. In addition, the Color Think graphing tool has no axis scales to refer to and you could not even quantify a plot if you wanted to.

mostly correct except for one thing. If you choose “Delta-E coloring” then you can move delta-E sliders to color the vectors according to how long they are. This can be an effective means of determining which vectors are worth worrying about and which aren’t.

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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