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Grayscale in CMYK image?


JohnnieB

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Dear gurus.
Did not find the answer anywhere else.
I am preparing a image for print with will be printed in CMYK, thing is I want the background to be in grayscale. When I test print on a Epson p9000 the background appears to have a tone that i can't get rid of.
You got any ideas what to do ? See attached images.

Best
/ Johan

Skärmavbild 2019-07-03 kl. 16.53.20.png

Skärmavbild 2019-07-03 kl. 16.53.27.png

Its for a record cover.
 

Redz166

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Hi JhonnieB Most digital printers dont really support Greyscale very well, as it is in itself a separate color space, away from CMYK,
you can replicate the same affect using the black separation adjusting the black percentage to simulate grey?
 

thebestcpu

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HI Johan
It would be easier to give good advice if you posted the image and not a screen shot. The screen shot comes with your display color space which may or may not be a good representation of the colors in your image.

I took your screen shot and pulled out the Hue (at full Saturation in middle image) and the Saturation (amplified to see the details) and noted that most of the image has a suble color cast.

If you want a good grayscale and the minimum, you need to start with an image background that is neutral color. The screen shot indicates it is not.
You can test the neutrality of course by using the info panel and hovering over pixels.

If you start with a measured neutral background and have an excellent ICC profile for the printer ink/paper combination, you should get a lot closer to a neutral background on the test print.
I am assuming that the record cover will be done by even a third printer. In that case, you need to ask them what color mode and color space then need the image. If they are doing the conversion from you RBG image to CMYK, they should have the already covered in their process yet best to specifically ask them since a gray tone background is important to you

To give better advice, would need to see the original image or a crop of it in the color space of the file you are creating (e.g. sRGB, Adobe RGB etc

Hope this helps
John Wheeler

Orig,-Hue,-Sat.jpg
 

JohnnieB

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Hi JhonnieB Most digital printers dont really support Greyscale very well, as it is in itself a separate color space, away from CMYK,
you can replicate the same affect using the black separation adjusting the black percentage to simulate grey?
Ok, If I desaturate the background, (which is what I have already done) the background will be like grayscale and the tone won't show in print? Or under which adjustment could I change the black percentage as C=0 M=0 Y=0 K100% ?
 

thebestcpu

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Hi JohnnieB
I will be the first to admit that I am not the expert on printing in CMYK.
For a given CMYK color space though I do know that C=M=Y does not necessarily yield a gray tone.
This excludes any issue with calibration with any given particular printer.

I have included a screen shot with three individual pixels in the background that have various brightness levels set with a a color sampling point. I have the info panel set to show the results in Lab space. A pure neutral tone would be when the "a" and "b" components are both zero and they are not. This is even given all three of those same points in CMY values are identical.

So I could be wrong, yet the assumption the C=M=Y makes a gray tone I think is incorrect.

As far as any actual prints on your printer, to get a good proof you need to have excellent color management from Photoshop out to the printer. That can throw things off as well even if you have a correct gray tone in PS.

Hope this helps
John Wheeler

Screen Shot 2019-07-03 at 6.13.56 PM.png
 

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