Expert: Kamal Krishna - 6/7/2007

Question
QUESTION: I am trying to convert a photo from color to grayscale in photoshop but I find that when I sample part of the image with the eyedropper tool and look at the color breakdown it still shows up in percentages of all colors. I even tried to create a halftone image and a bitmap image and the results are the same. Any suggestions?

ANSWER: Hi Eric,
I assume you have converted the image to greyscale using "Image > Mode > Greyscale" method.

The info palette allows you to see the color percentages in various modes like RGB, CMYK, Lab etc. etc.

Like you have said if you see percentages of all colors instead of only "K (black)". Then try doing this,
On the info palette you see a small eyedropper icon. Click on it to see a drop down of options, here select the first option "Actual Color".

Now you see only the percentage of the black color.

Let me know for further guidance.

---------- FOLLOW-UP ----------

QUESTION: First of all - thank you for answering my first question. I did as you suggested and did, indeed, see only percentages of black.

My follow-up question is this: If the image is truly a grayscale how does photoshop still manage to give a color breakdown if one so desires it? The reason I ask is that I am trying to create a graphic to be printed at a local print shop and they said that any photo requires four color printing as that is how photos are composed. So, is a grayscale image a grayscale image for all purposes or just for selected purposes?  

Answer
Hi Eric,
here's the explanation,
the breakdown because, the modes are all just different palettes of the same picture.

Usually a printer either uses RGB mode(laser printers) or CMYK mode(offset printers) to print any picture.

RGB printer - All the colors are generated using three colors Red, Green and Blue respectively.
CMYK printer - All the colors are generated using Four colors Cyan, Magenta Yellow and black respectively.

So When a black n' white picture is printed, the darkest black is just K, but all the other lighter shades are made of mixing other three colors(C,M,Y).

Its that way because having a printer with 16 million shades of greys is not practically a good idea. ;-)