in greyscale, color picker sees grey as CMYK instead of % of black

[Ira Liss]

[FONT=Calibri, Verdana, Helvetica, Arial]I am working on a greyscale document
that uses specific shades of grey.

For example, shades of grey composed
of 10%, 20% or 30% screens of black.

I create these shades of grey using percentages
of black (in the color picker) and my document’s
mode is set at “greyscale.”

But then,
when I use the color picker to analyze or tell me
what percentage grey color I’m using, it shows
me a CMYK mix for the grey color I made only
with black just a moment before.

For instance,
a moment after I make it, a grey that I made
with 20% black will show up as c16, m12, y13, k0
in the color picker instead of c0, m0, y0, k20.

How do I get the color picker to see my
10%, 20% or 30% of black as a percentage
of black and not see it as a mix of CMYK?

I’m trying to keep my greys consistent in a greyscale
document. I would prefer being able to double check
and see what percentage of black is being used
instead of what combination of CMYK.

I appreciate your help with this.[/FONT]

 

[Dreamers]

Sorry if I don't know the answer to that

But welcome to the forum

 

[Tom Mann]

Do this:

 

[Ira Liss]

Thank you for the welcome! And for your info panel window info.
(I was not aware of these preferences.)
Unfortunately, it did not take care of my issue.
Color picker still sees my greyscale 20% black as CMYK.

 

[ibclare]

I don't work in CMYK but I am getting the same values as you, so I suspect that the values you're getting are correct for this mode. The 4 zeros for black are designations for RGB. Maybe someone can fill us in on how cmyk makes its measurements. As I see it, those are the percentages of each color that will create the greys, the blacks, etc.

 

[Steve]

You're working in RGB right?
Switch to CMYK mode and try again.

 

[Ira Liss]

I don't work in CMYK but I am getting the same values as you, so I suspect that the values you're getting are correct for this mode. The 4 zeros for black are designations for RGB. Maybe someone can fill us in on how cmyk makes its measurements. As I see it, those are the percentages of each color that will create the greys, the blacks, etc.

You are correct about CMYK. When using the color picker (or simply talking about four-color printing), the numbers in the boxes are percentages of their corresponding color. The CMYK color mix contains four colors consisting of Cyan (C), Magenta (M), Yellow (Y) and Black(K).

 

[Ira Liss]

You're working in RGB right?
Switch to CMYK mode and try again.

I was working in greyscale mode. Even in that mode, the color picker gives me a CMYK breakdown or interpretation of my 20% or 30% screen of black. When I switched my file to CMYK just now, I saw that the color picker continued to show me a CMYK breakdown. (I wonder if I need to work with swatches to assure a consistency of greys across a number of BW documents.)

 

[Tom Mann]

Folks, I don't have a clue why you aren't seeing what I am seeing. Look at the screen grab in my previous post. You will notice that right above the center of my red arrow (ie, in the right half of the info palette), there is the letter, "k" (standing for "black"), and no hint of a CMYK readout. If I had placed the eyedropper over some part of the image before I took that screen grab, there would have been an appropriate number next to the letter, "k".

BTW, the color space for this screen shot was grayscale. I don't know what one would see if the image was in some RGB or CMYK space, but grayscale is what the OP requested and this is what I demoed, so I don't see any need to look at any other color space.

I'll be happy to help get to the bottom of this.

The best way to proceed is if one of you could post a full sized (ie, 1:1 ... don't down rez it) grab of your entire photoshop window showing all the palettes you have on display, but especially, the info palette. Please also zip up your problematic PSD file (so that the forum uploading software will accept it) and post that, as well.

Tom

 

[ibclare]

Color me confused. Here's a screenshot of my greyscale image and the cmyk percentages are there.

 

[Tom Mann]

Hi Clare: There are two color readouts in the info palette -- one on the left and one on the right. You have set the one on the left to display grayscale values. It seems to be reading them correctly. However, the right one is set to read out in CMYK values appropriate to the CMYK color space you selected in Edit / Color Settings.

The reason that the K value on the LHS does not equal the K value in the CMYK set of numbers is because the particular version of CMYK that you selected (ie, in Edit / Color Settings) makes gray tones out of a combination of all three of the CMY inks PLUS a bit of black. For certain combinations of printer, ink and paper, this approach gives deeper, more true gray and black tones.

So the two panels of the info palette are giving you on one side (a) it's best guess as to how much pure black ink must be used to get a particular gray level, and, on the other side, (b), the amounts of the four different colors that would be sent to a cmyk printer to get a particular gray tone.

HTH,

Tom

 

[dv8_fx]

I have no way to explain it fully but I hope this helps....... You have to use the 5% -100% shades of gray in the default color swatches. This will give what I think you need to see in your info - the exact percentage of black (represented as K),



If you were to create these color swatches yourself, PS will give you a percentage approximation of the color based on the default color modes. In which case wouldnt be an exact 5, 10, 15, 20 .... etc.

In the second image, I created the 75% black swatch. But the info shows it at 69%.



Same goes with the 3rd image. the 4th layer shows 91% black rather than the full 100% black as created.

 

[Tom Mann]

From the title of the thread, it seemed that the OP was unhappy because his eyedropper readout was displaying all four cmyk values, not a single "k" value, and, to make matters worse, when he turned on the the single "k" value eyedropper readout, its "k" value did not match the "k" in the cmyk readout.

However, other posts in this thread suggest that people are also concerned that when you set a neutral gray, say, R=G=B=128, the single "k" value often is not 50%.

The reason for this is because the color profiles chosen for RGB and for Grayscale differ in either gamma (or dot-gain). If you want to see for yourself that these color profile settings have an enormous impact on the eyedropper numerical readouts, do the following little exercise.

1. In Edit / Color Settings, make sure you are using the following standard settings, ie, RGB working space is sRGB, the CMYK working space is US Web Coated SWOP v2, and the Gray working space has a dot gain of 20%.

2. Perform the same experiment that you did before: Open a new canvas in Grayscale and fill it with R=G=B=128, say, with a color fill layer and using the color picker to get the desired mid-gray level.

3. Make sure the info panel display options are set to show RGB in the left half and Grayscale (ie, a single black value) in the right half of the panel.

4. As before, you should see that the "k" value is not 50%.


5. Now, we'll make one simple change that will put the RGB and "k" eyedropper readouts into perfect or near perfect agreement.

6. Go to Edit / Assign profile, click on the last option, ie, the one that allows you to select from various color management profiles on a drop-down menu, select "Gray Gamma 2.2", and hit "OK".

7. The brightness of your image will change substantially, and if you use the eyedropper, you will see that the RGB values have changed, but the "k" value has not.

8. Go back to the color picker for the color adjustment layer and re-adjust it to R=G=B=128 again.

9. Now, when you use the eyedropper tool, you will see that R=G=B=128 corresponds to a "k" value of almost exactly 50%.

The reason for the above behavior is that for agreement between the two eyedropper readouts, the color management profiles for each must have the same gamma, and we started with a situation where they did not.

The reason that this complexity exists is because different output devices have different properties. For example, two different printers may produce grays of different brightness even if you send both of them a command to produce 50% gray. To try to ensure that your image has the same brightness whether it is sent to your monitor or to different printers, Adobe introduced color management into PS, specifically, the ability to have different output device color profiles.

I hope the above explained why a difference can exist, and how to force the two readouts to agree.

I'm sure there are other opinions on this, but personally, for consistency, I would set my output device profiles to what they need to be to represent my particular monitor, printers, etc. and not worry that the two eyedropper readouts do not agree. In such a situation, to get reproducible grays, just be consistent. Always use swatches, or always use the RGB eyedropper readout, or always use the "k" eyedropper readout, etc -- just don't mix methods.

HTH,

Tom