Color Management & Monitor Calibration

PM
Posted By
Phil_M._Clark
Jul 26, 2004
Views
407
Replies
13
Status
Closed
We are using Colorvisions monitor calibration system to improve monitor color, and it is working. However we have come across a puzzling problem in Photoshop. When using the monitor calibration as a profile for the work space we see a hard edge when air brushing a light color on a dark background.

I am thinking that by having the monitors color space set to the calibrated profile AND having photoshop use the calibrated profile as its work space we are effectively applying the monitor calibration curve to an image twice, causing the hard edge. Is this true? If so, do you have a recommended color space to use for new images?

I am really stumped over this and several of our artists are getting frustrated by the appearance of the hard edge, so any help will be greatly appreciated.
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B
Buko
Jul 26, 2004
Don’t use the monitor profile as a working colorspace.

Working colorspace is sRGB, Adobe RGB, Bruce RGB.
GB
g_ballard
Jul 26, 2004
Don’t use a custom monitor profile as a working space!

AdobeRGB is preferred (if you understand HOW to Convert it to target device spaces) or sRGB.
R
Ram
Jul 26, 2004
Phil,

What Buko and G B say.

Whoever told you to set a monitor profile as a working space is a very confused individual. Monitor profile, working space and ink/paper/printer-combination profile are three different things, each one having its distinct place in your workflow.
BF
Bruce_Fraser
Jul 26, 2004
The hard edge is caused by working in a gamma-compensated space (which any rational working space will be). The fix is to activate the "Blend RGB Colors Using Gamma 1.0" checkbox in Color Settings>Advanced.

But don’t use the monitor profile as a working space!
R
Ram
Jul 26, 2004
Thanks for the reminder, Bruce.

Note to G B: –>

Here’s a potential wrinkle: Using "U.S. Prepress Defaults" in Color Settings > Settings disables the "Blend RGB Colors Using Gamma 1.0" check box in Color Settings>Advanced. Therefore, if one follows that part of the recommendation in your workflow page, maybe folks ought to be guided to checking the "Blend RGB Colors Using Gamma 1.0" check box right after selecting "U.S. Prepress Defaults".

I liked your suggestion to use "U.S. Prepress Defaults" as a visual check to make sure your color settings haven’t been messed up; but this blending thing could be critical to many users.
GB
g_ballard
Jul 26, 2004
Point noted, thanks.

US Prepress Defaults is a brainless setting that "quickly gets everyone on the same page" with functioning Color Management Policies in place.

I think I’ll leave the Advanced tab (and setting an appropriate CMYK) for my 202 rant. I’m still trying to get my 101 workflow right 🙂
GB
g_ballard
Jul 26, 2004
But now that it’s been brought up, does the "Blend RGB Colors Using Gamma 1.0" check box affect the actual source file-to-print (or does it only affect the monitor render)?
BF
Bruce_Fraser
Jul 26, 2004
It affects RGB blending, either when painting or when using layers set to Normal blending, so it can certainly have an effect on print—it’s not just a display thing.
PM
Phil_M._Clark
Jul 26, 2004
Thanks all. I am still new to calibrating monitors and using profiles and working with a color management workflow. So I was going from the assumption that since we had calibrated the monitors we should set that as the workspace. Now that I know better I can now get the problem fixed. Since we do work in an RGB environment I will try turning on the advanced options and blend RGB colors using Gamma 1.0 if just using the AdobeRGB colorspace doesn’t have the desired effect. I may even test what effect it does have to see if that is what we want to do anyway.

Thanks again for the help. You have saved what is left of my hair.
O
Oh2
Jul 26, 2004
While your already discussing Advanced Mode "U.S. Prepress Defaults" in Color Settings, I have one more quick question. In the Conversion Options area, under Engine:Adobe (ACE) do you recommend Perceptual or the default Relative Colormetric setting in PS7?
GB
g_ballard
Jul 26, 2004
Phil,

The theory goes:

CAPTURE as much color info as possible (in a 16-bit AdobeRGB or RAW camera), and PRESERVE that information during editing.

The trouble with bringing the color into a monitor-type space (sRGB, MonitorRGB, AppleRGB, ColorMatchRGB) is that they "clip" a small color gamut.

I like to think of the clipping process as flattened cookie dough (of color info). The cookie cutter clips out the shape (to make the desired color shape), and the remaining dough (the unused information) is disgarded (and irretrievable).

We can Convert (add a bigger shape around the clipped shape) back to a higher gamut, larger color space, but we gain no additional information (than what is left of the smallest clipped shape). Other words, all that is left between the clipped shape and the new space is empty space.

Further, it makes little sense to base our color on a custom calibrated monitor profile (it’s how Photoshop 4 works) because:
1) MonitorRGB is a small gamut, and
2) MonitorRGB is based on one unique specific device profile. Better to pick a high-gamut, device independent space like AdobeRGB…

I guess my point is:
Once the shape is clipped out of the source, Converting back to a bigger space only places a bigger cookie cutter around the shape — there is no gain in information, only empty space in a larger container.

Here’s more on 16-bit, scanning, RAW, Adjustment Layers: <http://www.gballard.net/psd/16bitworkflow.html>
R
Ram
Jul 26, 2004
Oh2,

Personally, I use Relative most of the time. Simplistically you can say that Perceptual compresses the colors; Relative clips the colors that are out of gamut if there are any. I find that Relative works best for the vast majority of my images.
AR
Andrew Rodney
Jul 26, 2004
It really doesn’t matter what intent you place here unless you use Mode Change which uses that setting. If you’re into "blind" conversions that’s a good way to fly. Much better is to use Convert to Profile, select the profile you intend to use for the output task at hand, toggle the various intents and pick the one you like best. Now I will say that 9 times out of ten I’ll usually pick RelCol and thus it’s a good default for color settings if you use Mode change. But every once in awhile, Perceptual or even Saturation might make a world of difference in the conversion. You just have to look! Since profiles don’t know anything about images (and you do), it’s usually worth the extra minute to look at all this either in Convert to Profile or by setting up a group of saved, custom soft proofs (for each intent).

Of course if you’re about to convert 800 widgets on a white bkgnd for the same catalog, I can’t fault anyone for loading the CMYK profile in color settings and simply automating Mode Change (action, batch, whatever). You don’t always have to look at each image…

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