Re: MeasureTool Compare question
Re: MeasureTool Compare question
- Subject: Re: MeasureTool Compare question
- From: bruce fraser <email@hidden>
- Date: Wed, 16 Mar 2005 10:10:32 -0800
At 12:36 AM -0800 3/16/05, Marco Ugolini wrote:
In a message on Tue, 15 Mar 2005 12:45:28, Matt Nelson wrote:
That is a clever script: I tried it and it works, but I think that I have an
alternative procedure which, compared to this one, is definitely less
time-consuming.
Marco,
This is a procedure I've used on and off for several years. On and
off because ColorLab, as unsupported freeware, often gets broken by
new OS releases.
The key functionality that ColorLab offers is the ability to turn
text into pixels and vice versa. I keep 'pixels' versions of all my
testcharts, where each patch is a single pixel, which I make by
loading the target reference files into ColorLab, as you outlined,
and save them as TIFFs. Conceptually, you can do the conversions in
ColorLab, but...
I prefer to do the actual color conversions in Photoshop, because
that's where my color conversions happen in the real workflow, and
I'd rather use Adobe's ACE CMM and have access to their Black Point
Compensation than do the color conversions in ColorLab. On the
testcharts in pixels form, the color conversions are very quick, and
it's pretty easy to bounce back and forth between Photoshop and
ColorLab.
I'm a bit leery of steering people towards ColorLab simply because it
IS unsupported freeware, but it's by far the easiest way I kow to
turn pixels into text and vice versa.
The things that currently seem to be broken are
Export to Lab TIFF (the signs on a* and b* are reversed, and the
values from 0 to 128, with either sign, are inverted).
The Comparison function, which is similar to MeasureTool's, crashes
for me every time.
So here's my somewhat streamlined version of your procedure.
1.) Launch ColorLab.
2.) Open ECI2002V.txt reference file
3.) Choose File>Export, choose TIFF image as the output format,
change the extension manually to .tif (ColorLab won't do this for
you), and click Save.
4. Open the TIFF in Photoshop.
5.) Assign the profile you're testing.
6.) Convert to Lab, Absolute colorimetric
7. Save the Lab TIFF.
8.) Open the Lab tiff in ColorLab.
9.) Choose Filters>Conversion>Spot Colors
10.) In the ensuing dialog box, click Enable (ColorLab automatically
enters the correct dimensions).
11.) Choose File>Export, choose text as the output format (again
changing the extension manually), and save.
You now have a text file representing the Lab values predicted by the
profile you assigned in step 5, that you can open in MeasureTool.
You can print the pixels-format Lab TIFF created in step 7 by setting
the resolution to 4 ppi. That gives you 0.25-inch patches, which are
typically big enough to measure.
Bruce
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