Re: Finding CIELab Values from Target Chart TIF
Re: Finding CIELab Values from Target Chart TIF
- Subject: Re: Finding CIELab Values from Target Chart TIF
- From: Joseph Yates <email@hidden>
- Date: Thu, 29 Apr 2010 15:53:48 -1000
- Thread-topic: Finding CIELab Values from Target Chart TIF
on 4/29/10 2:13 AM, Terence Wyse wrote:
> Joseph, what I think you've got (the 140 patch TIFF file) is a *linearization*
> or calibration file, not a file for creating a *profile*. In any case, as
> others have explained, you've got *device* values (CMYK) but no Lab values.
> The Lab values is something that needs to be discovered from printing a
> profiling chart.
>
> There wouldn't be Lab values associated with a linearization/calibration file
> as the behavior of the device is unknown. In simplest terms, you print the
> linearization file, measure it using something like an EyeOne Pro or similar
> (maybe even a densitometer) and then that data gets fed into their software.
> At that point, the software has some sort of expected "linear" behavior for
> your device and does a basic curve adjustment to bring the device into
> conformance with that expected behavior. Linearization is rarely done using
> Lab values (although it can be) but is typically done using density values or
> "dot gain" via density and a dot area formula (Murray-Davies typically).
>
I suppose then what I'm after is some way to evaluate the results of this
PhaserMatch calibration - how well (or if at all) - it brings the device, as
you describe - into conformance with this expected "linear" behavior.
I was headed in the direction of CIELab values - since the PhaserMatch
software shows me the results of the measured patches as CIELab values - and
I can also see the results of the post-calibration re-printed & re-measured
patches as CIELab values.
But it seems to me - evaluation or comparison of these 2 sets of Lab values
- pre-calibration and post-calibration - only shows the color difference
between the 2 states - and not how close or far away it brings the device
into conformance with - it's repeatable linearized state.
Regards,
Joseph
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden