Re: matching paper white
Re: matching paper white
- Subject: Re: matching paper white
- From: Terry Wyse <email@hidden>
- Date: Fri, 11 Mar 2005 08:24:23 -0500
If you're doing this in Photoshop's ColorPicker, make sure you've
loaded your printer profile as a working space and set the rendering
intent to absolute.
Also, if you've got Measure Tool then I assume you've also got Gretag's
Color Picker. Why not simply load your printer profile in GMB Color
Picker and let it tell you what the optimum RGB value would be for
matching the paper tint? Just a thought.
Terry
On Mar 11, 2005, at 12:03 AM, Michael Fox News Accout wrote:
I’m hoping someone can help me with the following problem.
I’m trying to tint the paper to match the white of the mat board. My
issue is figuring out the exact, specific sequence to accomplish this
without lots of trial and error.
I have created several test prints and things just don’t seem to come
out the way I expect. With all the instrumentation available today,
surely there’s got to be a simple and straight-forward way to
accomplish this. I mean, what’s the point of all the multi-thousand
dollar instruments, profiling software, etc., if color matching is
still just trial and error?
Here’s what I did. Please correct me if I’m wrong:
1) Measure paper white of the mat board with a
Spectrophotometer. I’m using the Spectrolino with Gretag Measure
tool. For this particular mat board, I get LAB = (95.1, 0.6, -0.1)
2) Measure paper white of the print paper. For this particular
paper, I’m getting (91.4, 0.3, -1.9)
3) Determine the difference (paper – mat) = (-3.7, -0.3, 1.8)
4) Open a new document in Photoshop with the corresponding
printer/paper profile.
5) Edit > Fill with the above color (paper – mat). Photoshop
only accepts whole numbers for LAB colors so everything must be
rounded to the nearest integer value.
6) L: Since L is negative (paper is already darker than the mat
board), so L should stay at 100.
7) b: Since a* can be rounded to 0, no a* correction is needed.
8) b: I need a tint of 2 (1.8 rounded) in the b axis to offset
the -1.9 paper color.
9) LAB: So, I should aim to set the value to (100, 0, 2)
So, I go to the Photoshop Color Picker and enter LAB values of
100,0,2. This show the corresponding RGB value of (255,255,255) which
tells me that 100,0,2 is not a distinguishable color for this
printer/paper. However, if I enter RGB values of 255,255,250 to
255,255,248, then LAB values show 100,0,2. (Perhaps this is a bug in
Photoshop Color Picker).
So I printed a color patch of 255,255,249 – right in the middle of the
above values. Then I measured the result. But the color still reads
the same as the paper white.
So, I figure that there’s got to be a way to do this without creating
a test print of all the possible RGB combinations and then measuring
the output to find the right match, and then repeating that for every
type of paper/printer that I use.
Ideas?
Michael
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
email@hidden
This email sent to email@hidden
_____________________________
WyseConsul
Color Management Consulting
email@hidden
704.843.0858
http://www.colormanagementgroup.com
http://www.wyseconsul.com (coming soon)
_______________________________________________
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