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I'm new to the forum and I would like to ask a question.

To print a postcard I have to submit my design using a CMYK template provided by the printer (Moo printing).

The design is a grayscale image made in Photoshop RGB mode. I tried some things:

1/ converting the image in Image Mode > Grayscale and then dragging & dropping in the CMYK template

2/ converting the image by Edit > Convert to profile > CMYK and dragging & dropping in the CMYK template.

In both cases the image CMKY template does not look perfectly grey. There's always a hint of red or blue/green.

I also don't find a way to objectively test this, what looks just a bit red on my screen may be perfect neutral grey on print. How do you know that there's not going to be any color on the print? Using the hue/saturation in CMYK also not takes the color out...

What is the best practice for these types of images?

Thanks.

Gigi

  • Are you working with a calibrated monitor? Also could you post an example of the problematic part of the image in CMYK, so that others can check it? – Billy Kerr May 31 '17 at 13:08
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    Can you ask for a test print? If it prints fine your file is correct, your screen is not. Have you checked the CMYK values? – Luciano May 31 '17 at 13:38
  • The monitor is calibrated with the windows utility. It's not exact science, but from experience, what I see on the screen corresponds perfectly with my inkjet printer. When I use a local printer, the quality is mostly good. But sometimes we need to correct some small things (like add a little brightnes, ...). – Gigi Jun 1 '17 at 16:53
  • The image is a black and white photograph. There's not really a problematic part but just a general color shade. I'm also not used to work in CMYK space, i.e. when you lower the saturation with the hue/saturation command, the saturation is not removed but at -100 the image turns red and at +100 it turns blue. Using the brightness/contrast command has a similar effect. – Gigi Jun 1 '17 at 16:55
  • Hi Luciano, where can you check the CMYK values? – Gigi Jun 1 '17 at 17:23
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Double click each color so it brings up the attributes, remove all Cyan, Magenta, and Yellow; make sure only the Black (K) is all the way up.

To see if it looks good, save it as a PDF and open it, the reddish, greenish color should be removed.

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    Where do you double click a color to open the attributes? I'm working with a photograph (not a logo with a few colors) so it's not really possible to double click each individual color. Or do you mean using an adjustments layer 'selective color' and take out the cyan, magenta and yellow for all the color channels? – Gigi Jun 1 '17 at 17:00
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I am not really worried about how do you see it on your screen. Your screen could be turned off and your file could be right or wrong.

I am sure that does not make feel you better. Sorry for that n_n

Ok. First of all, Calibrate your monitor, at least with a gamma pattern calibrating the 3 channels separately.

Your computer should have a program to do so. On windows look for the Calibrating Color application.

As you say removing saturation does not remove your color tint your monitor simply does not have this minimum calibration.


But that is just to see things better. The printing process is a more complicated part.

Option 1

  1. Change your image to grayscale. Select it and copy it to your clipboard.

  2. Open the template and choose the black channel. Paste your image on this channel only.

This will give you a grayish image because the black is not black but a dark gray. You could adjust the levels to darken a bit the image.

Option 2

Just paste the grayscale image to your CMYK template directly and trust the template will truly have the correct profile and the printer makes an awesome work controlling the ink.

Option 3

Just prepare a grayscale image and ask the printer (probably not this one) to print your file in a deep black spot ink.

Option 4

Use option 2 and live with some degree of colorization on the image.

You are using 4 inks so any error can happen, but there is some level of tolerance we must accept unless you pay the Option 3 and stand on the penthouse when they print your work.

  • I think option 2 above is best. If you convert the image to grayscale and are pleased with how it looks, save it and then convert it to CMYK, you should have only black in the final image. – ispaany May 31 '17 at 15:15
  • Hi, thanks for your answer, there's a lot of good info in it. Option 1 is pretty good, but the image is somewhat 'duller' than the original one, even with levels and contrast edited. But I think it also gives a good base to compare what 'true' gray looks like. I think I'll go for option 2 and 3. I'm using an online printing service, so test printing is not ideal since it's both expensive and takes time to ship the test prints. But it might be a good idea to print a set of images with different colors to have a 'color checker' as a tool to compare future prints with. – Gigi Jun 1 '17 at 17:30
  • The thing with removing saturation for a grey image in CMYK mode in Photoshop is that it doesn't remove the saturation, i.e. at -100 the image has a red shade and at +100 it turns blue. Using the brightness/contrast command has a similar effect. If this is related to the screen calibration, then I should lower the red values on the screen, right? But since the last prints I made had also this red tint, then it does mean that the screen is correct. So this is why I get a bit confused by using the CMYK mode... – Gigi Jun 1 '17 at 17:40
  • No. You should not touch an image on CMYK. Converting an image to CMYK is the last step. You should not manipulate it furrther (Unless you are really an expert). You either desaturate a RGB image or simply convert it to grayscale and only then convert it to CMYK. – Rafael Jun 1 '17 at 19:25
  • Ok that's clear, thanks. Just one more thing: I want to print a color checker to have a set of colors to compare the output from the printer with what I see on the screen (for future prints). Does anybody have a standard color checker? I can also google one, but apart from something that looks like a nice set of colors I don't really know what's important here... – Gigi Jun 6 '17 at 9:06

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