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What is the best way to print a poster with: black and white image + color graphics?

Forum|Forum|1 year ago
January 22, 2025
3 replies
916 views

Hi guys,

I have some issues (both in digital and offset printing) with a poster that includes: a black and white image + color graphics.

– When I export my print .pdf file with a CMYK color profile, I get a deep black but I always end up with a color cast on the black and white image, as a result of the printing process (the color cast can be C, M or Y in different cases).

– I can't export the whole print file with a grayscale color profile, because the poster includes not only the black and white image but also some color graphics.

Also, even if the poster was only black and white: with a grayscale color profile there is no color cast on the black and white photo, but apparently I can't get a deep black, which is only achieved by adding C+M+Y (almost 70% of each color to reach a total black of 300%). Is this correct? Is there any difference if I import a grayscale .tif into my .indd file and then convert it to 300% black using the corresponding color swatch?

I have tried several export solutions but have not been able to solve the problem optimally, especially with typographies that do not specify a specific color profile to use with their machines.

– I converted the .tif image from grayscale to CMYK, using the Uncoated Fogra39 color profile (apparently still a European standard) and then exported the .pdf file with all the graphics using the same color profile, notifying the typographer that this specific profile was used. By providing this reference to the printer I hoped to get an accurate color match. Instead, the black comes out deep but I still end up with a color cast on the black and white image. On my screen, however, the color rendering is perfect and I do not see any color cast on the black and white image.

– I also tried setting the .tif image to grayscale and the artwork to CMYK, then exported the .pdf file without any color profile. But in this case, the file still requires a color profile to be opened, and when I choose a CMYK color profile (like Uncoated Fogra39) in Adobe Acrobat the grayscale image becomes much lighter and washed out, with the black looking more like a dark gray. I expect the same result in the printing process. Or does it only happen on screen?

I need to print the same poster with more than one typography, to produce multiple communication materials with different adaptations of the same artwork. So I need the colors of the various materials to be as identical as possible. For this reason I also chose to send the .pdf files to the various printers with the same color profile included (always specifying it). So for now the best way I found to solve this case is to convert everything with the Uncoated Fogra39 color profile and pray that the color cast is not too strong.

I wonder if it would be better to prepare the .tiff image in CMYK (color profile fogra39) and then export the .pdf file with image + artwork without including the color profile. My fear is that some typographers will not take into account my reporting of the color profile and perform a further conversion during printing.

Has anyone else had the same issues with this type of print? Have you found a better way to fix it? Thank you so much for sharing.

Cheers,

D

E

Eugene Tyson

Community Expert

Hi Didier

To avoid the colour cast on your black and white images, the best approach is to make sure they are prepared as grayscale in Photoshop and if you're converting them to CMYK to only the K channel active (which is the same thing as a grayscale image...). This ensures that no cyan, magenta, or yellow is added, which is the main cause of the colour cast.

You can do this with Edit>Convert to Profile> Select the colour profile and then perform an Gray Colour Removal (GCR) - which should move all the channels to the Black channel only

It would be best to leave your grayscale images as Grayscale - what you've done converting CMYK to grayscale isn't necessary but you've already done this - as your image was originally Grayscale placing that in InDesign would have been more efficient - and using PDF X4a to export your PDF as PDF X4a shouldn't perform any colour conversion - whatever your Photoshop settings are for your images should retain that.

This might be happening for you - which when converted to CMYK it's in all Channels and why you're having colour casts

Just to note - the result below is the exact same as a Grayscale image, it's just going to be a CMYK image with all the channels on the Black channel - which is the same thing as a grayscale image... so it's really pointless I think. As said earlier it's best to leave your images as Grayscale - and use PDFX4a when exporting the PDF.

To resolve your issue with CMYK grayscale images

Edit>Convert to Profile

Click Profile and choose Custom CMYK
Select your Colour Profile and then GCR and then Maximum
(Sorry for the bad screen shot it wouldn't work any other way)

Then you'll see all the other Colour Channels are empty - except Black

For a deep (rich) black, it is true that a mix of C, M, Y, and K is used, such as 50% of C/M/Y with 100% K. However, this is typically applied to large black areas in graphics, not black and white photos. For your images, sticking to pure K is better to avoid any colour issues.

When exporting, using PDF/X-4 is recommended. This format retains transparency and embeds your colour profile without forcing any unnecessary conversions. Including a standard profile like FOGRA39 is a good practice, as it provides a consistent reference for the printers. Make sure to clearly communicate this profile to the printing house and confirm that they will not convert it during their process.

For mixed content like grayscale images and colour graphics, you can place the grayscale images as is and ensure the colour graphics are CMYK using the same colour profile, such as FOGRA39. When exporting to PDF/X-4, this will keep both elements in their correct colour spaces.

Finally, I strongly recommend always requesting a print proof. It might be an extra step, but it is the only way to ensure the final result matches your expectations, especially when working with different printers. If you notice a colour cast in the proof, you can make adjustments or discuss with the printer before proceeding with the final run.

I hope this helps clarify things. Let me know if you need more details.

D

Didier_RigolletAuthor

Participating Frequently

Hello Eugene,

thanks for your reply, it was really helpful. I made a couple of attempts to check the result of different types of color profile and export.

1. I used the image in 2 versions: the original .tif with a grayscale profile (gray gamma 2.2) and the same .tif converted following your instructions for custom CMYK.

2. I placed the 2 images in different pages of my .indd file, adding CMYK colored squares on top of them.

3. 3. Then I exported the file (using the High Quality Print as profile + PDF/X:4-2010 as Standard) in 2 different ways: without color conversions and converted to destination (with Coated fogra39 color profile).

As a result, I noticed that the Grayscale versions look more washed out, both when exported with and without the converison to the color profile. On the contrary, the custom CMYK versions are slightly darker but still closer to the original image (with and without the converison to the color profile).

Another important thing I noticed is that when opened in Photoshop: the file with the grayscale version of the photo without a color profile is converted to CMYK using the 4 colors. The same does not happen to the grayscale photo with a color profile. Doesn't this imply the risk of getting a color cast? The printer still has to convert the file to a CMYK profile, so perhaps it is better to avoid this option. What do you think?

I encountered the same problem both using PDF/X:4-2010 as a Standard (with High Quality Print as the profile), and using PDF/X:4-2008 as the profile, with PDF/X:4-2010 as a Standard (which gets automatically selected).

There doesn't seem to be any difference in the output of these 2 different export settings. Do you think PDF/X:4 should be used as a Standard or a profile? Would it be better than using High Quality Print as a profile? Someone advised me to use High Quality Print as a profile and PDF/X-1a:2001 as a Standard, do you agree?

In conclusion, the best way to solve the problem seems to be: custom CMYK profile for the .tif + conversion to coated fogra39 when exporting from .indd to .pdf

This way the black and white image does not look washed out and the .pdf is already set to a standard CMYK profile, which keeps the CMYK color mostly consistent and the black image only on the K channel. What do you think? Thanks for your help!

Cheers,

D

E

Eugene Tyson

Community Expert

If you're controlling the CMYK profiles then pdfx4 exports without any further conversations.

You can assign a profile, which will be the PDF view you see.

If the printer is using a different furniture then it will be converted on their end to that profile.

If you end a profile it might guide them.

But you really need to talk to them.

Robert at ID-Tasker

Legend

@Didier_Rigollet

You should request "color proof" anyway.

D

Didier_RigolletAuthor

Participating Frequently

Thank you for this advice. I usually ask for a print proof and have corrections made on the color casts, which however fade but do not disappear completely. Furthermore, it is an extra step that is often annoying for the customer. Also for this reason I would like to understand if there is a better solution in terms of print profiles and export methods.

Robert at ID-Tasker

Legend

@Didier_Rigollet

ALWAYS request print proof - ALWAYS.

NEVER EVER let customer ignore it.

Who - if not you - will be financially reponsible if something goes wrong?

Unless, customer will sign a document, that he takes full reponsibility for the end effect - without his acceptance of print proofs.

James Gifford—NitroPress

Legend

You give every detail except what kind of printer — and what print technology — you're using.

Getting good results with an extreme range of tones like this from anything but a commercial printer with calibrated profiles and advanced features is a crapshoot; few SOHO printers can do more than a sort of generic. center-spectrum job.

But a starting point would be a calibrated print profile for your exact printer model, and possibly two-pass printing to handle K and then CMY separately.

ETA: And what might be the real solution is to have a print service print the poster for you, using pro-level file management and color calibration for a commercial-grade printer.

D

Didier_RigolletAuthor

Participating Frequently

Thanks for the reply. I happen to print the same poster (in various sizes and for different applications) with various professional printing houses – both digital and offset. I do not know the exact model of the machines they use for printing, so I have asked several times for a color profile suitable for their needs. In most cases I have not received a clear answer and I have been told that the standard color profile CMYK coated fogra39 was fine. However, I continue to encounter the problem of color cast on black and white images – espcially with digital printing (where I cannot separate K and CMY).

James Gifford—NitroPress

Legend

Okay. You weren't clear that this was via commercial printing, so not all of my reply is relevant.

But in the end —

Digital printing has its limitations, the more so when you push towards the limits of color gamuts and dynamic range.
You are completely dependent on the practices of a commercial printer; if they don't have a range of color profiles to suggest, including one or optmized for your project, there' s very little you can do. Any efforts at trying to "precorrect" or adjust the results from your end might actually backfire as the printer "re-corrects" your color curves according to its standard practices.

I suspect most of this comes down to the first item, though. If you're not using simple colors that fall 100% within the printer's gamut, and gradients that don't exceed the printer's dynamic range (and "steps") — you can only adjust your design to do better given those limitations.

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