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How do you convert a grayscale bitmap a to one CMYK color in Photoshop for printing, eg. C61, M41, Y58, K16 green?

enter image description here

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3 Answers

up vote 7 down vote accepted

The easiest way to do this is to open your image in grayscale mode in Photoshop (or convert to grayscale mode if it opens it in RGB/CMYK format).

From there, choose Image->Mode->Duotone.

Make sure the type is set to Monotone. Ink 1 will be set to black. Click on the black box, to access a color picker. Choose the color you want (use the color libraries button to get to the list of Pantone colors.) Click okay, and you are done!

Here's how it would look using the RGB values you specified.

Using the RGB values specified to make a monotone image

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Hey, I want to convert it to #6c7a6c not a Pantone color. –  Josh Nov 20 '12 at 2:27
    
In the color picker, there should be a place to put in your hex value. What version of Photoshop are you using? –  Anne Nov 20 '12 at 2:41
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#6c7a6c is an RGB color which is inappropriate for print. You need to pick a Pantone color. –  Scott Nov 20 '12 at 2:46
    
According to Photoshop's algorithm, PMS 5625 is a fairly close match to your RGB value. –  Anne Nov 20 '12 at 2:52
    
Why not just use CMYK? –  Josh Nov 20 '12 at 3:22
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For completeness, I'll add here that is not always necessary to alter the greyscale bitmap file. If it is in TIFF format and greyscale, and you are using a layout program (indesign, Quark, foo etc) you can use your layout program to tint the image to an exact swatch.

For indesign, you place the image, set the background color of the box to whatever (paper, black, red, purple etc), and then switch the context to the content of the box (aka the image is highlighted brown) and set the foreground color.

The greyscale image essentially acts as an alpha channel for the foreground color. (does not involve clipping paths etc.)

I like this method because it does not alter it (same as the accepted answer,which I upvoted), and it also ensures that the layout program uses the same CMYK or spot color values as all other items in the document (eliminates any chance of a profile or {magic} color adjustment).

In addition, if you change the swatch, it cascades the change throughout the document without the need to edit individually placed files.

Additionally in addition, you can use the same image without alteration with muliple color values. (Think Andy Warhol)

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I completely forgot you could it that simply. Although you might not want to do this if you need to use the colourised image file in other contexts, e.g. output an RGB PNG for web. –  e100 Nov 21 '12 at 10:53
    
probably even then it will work (milage may vary): presumably you will be exporting a page (etc) and all the items will be afflicted with color drift to the same degree. In this sense it may be desirable for color consistency (consistently inaccurate . . .). Your logo will match the spot color shapes, etc. –  horatio Nov 21 '12 at 15:32
    
I meant an individual image, not a page - I used to have to regularly produce a monotone banner images which would then be used included both in a printed page layout and in a companion web page. –  e100 Nov 21 '12 at 15:36
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An alternative method, if you're not needing to print, is to use blending modes, this way you can pick your exact color:

enter image description here

enter image description here

Simply fill a layer and switch out your blending mode!

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One thing to be careful of if you're using this method is that if you give it to a printing service, it will still be RGB/CMYK format (they will show up in your channels tab). Additionally, this isn't truly one color, as there are areas that are black, or have black mixed with the color. –  Anne Nov 20 '12 at 18:44
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Right, and it's not meant to be a solution for printers, your answer is much more qualified for that. The aim of my answer was to show how to use an exact hex-value color (or any other valued color) and easily blending it on top of something. I figure it'll help someone out in the future :) –  Johannes Nov 20 '12 at 18:46
    
Definitely! It wasn't stated whether the OP would be using a printing service, so this is definitely useful information. :) –  Anne Nov 20 '12 at 19:07
    
But this question does now specifically mention printing, and so I have to say it is poor advice in this context. –  e100 Nov 21 '12 at 10:52
    
I made my answer more clear in the fact that this isn't designed for print. The original question made no mention of print and it is a perfectly valid way to add color to a grayscale image and my answer may help someone out in the future who doesn't care about printing. At the time my answer was perfectly valid and I'm not going to retract my answer just because the question was changed making my answer "poor advice." Down voting after the question's context has changed just doesn't make sense to me. The important answer is accepted and most voted on. –  Johannes Nov 21 '12 at 18:53
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