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My print knowledge has gone a little rusty so I was wondering if someone might be able to clear something up for me.

I am designing a box which has a photo that fades into black around the edges/in the photo background around the product. The client wants the background of the box to also be black.

From the few prints I've done a while back I used 100% K for the black. However, the photo is RGB in Photoshop. Obviously, the blacks don't match up.

Can/should I print using a rich black background for the rest of the box using % blend of CMYK that blends into the photo from Photoshop or should I convert the photoshop file RGB black into 100% K black? If I were to use the CMYK rich black, I'd convert the photo before print for press but would I lose the quality of the black (and photo) if I converted the photo to 100% K and went that route.

The route I am looking into is to CMYK rich black the box background and insert and convert the RGB photo. Would this be okay at print with plates and alignments?

To overview, excluding images, the rest of the box has some red and white text.

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    Why mix up CMYK and RGB, can you convert your photo to CMYK? How about print the image with the black being transparent, or if you're printing directly on the box just don't print the black? – Luciano Jun 30 '17 at 12:17
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    Possible duplicate: graphicdesign.stackexchange.com/questions/93572/… (Although it refers to InDesign rather than Illustrator the methodology is the same) – Scott Jun 30 '17 at 18:13
  • I was looking that post... :o) – Rafael Dec 28 '17 at 1:05
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Use transparent edges for the black edges in PS AND use rich black in InDesign for the background.

Here is an example of neutral rich black: C50%,M30%,Y30%,K100% I would convert the PS-Image in your desired CMYK-ICC-Profile and place it in InDesign. You could also sample the black with the Eyedropper in PS and use this as a background in InDesign. There is not ONE solution and NO totally right.

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One way to do this is to work in RGB until the point where you export a CMYK pdf (I assume you do the box design in InDesign/Illustrator).

  • In Edit/Color Settings... (in either InDesign or Illustrator) take a look at the Working Spaces/RGB setting and make sure that is is set to something standard (it is probably set to sRGB which should be fine).
  • You should also make sure that the Working Spaces/CMYK is set to a CMYK profile recommended (and provided) by your print shop.
  • Now check if the RGB profile of your image is the same as the Working Spaces/RGB setting. If not convert the image to that profile.
  • Do the fading of the image in Photoshop. Make sure that the edges of your image are entirely RGB black (0, 0, 0). Do not let the fading start at the edge of the image. Maybe you have to expand the canvas with a black margin to be 100% sure.
  • Now place the RGB image in InDesign/Illustrator and make an RGB black background and place additional text and boxes in RGB as well.
  • When you export/save a pdf, set Output/Color/Color Conversion to "Convert To Destination". And set Output/Color/Destination to "Document CMYK", which should be the CMYK profile you chose earlier. Profile Inclusion Policy is set to "Include Destination Profiles" so the print shop can easily identify the profile you have used.

When converting an RGB black to a CMYK profile, you are making the darkest neutral black possible using that color profile (which ideally fits the capabilities of the physical device doing the print). No need to fiddle with the CMYK values yourself unless you know exactly what you are doing.

The downside of this approach is that this rich black color totally saturates the paper with ink which could be a problem with some printing method because of longer drying time, smearing etc. There is also a risk of negative text becoming blurry if the print is a little out of register.

You should really ask your print shop for support. If you are printing the box yourself, just forget about CMYK. Work in RGB, and make test prints to make sure it looks like you want it to look. Most printers convert your CMYK file to RGB before converting it back to its own secret CMYK profile, so your initial CMYK values are gone.

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There are two parts of this question. Take a look at this answer about what is a rich black.

When should I use rich black?

In your specific case, there are a couple of options.

Depending on what is the content of the image and how important is that black on it you could choose either option.

I. Use the CMYK values given by the color profile.

My approach is that the CMYK values SHOULD be determined by the color profile you are using. This is similar to @Wolff's answer.

This is extremely important.You need to define this profile. As the black is going to dominate the print, I recommend that you use a color profile that has a max TAC of 300%, like Swop2. Some others like fogra 39 put some more ink, about 330%.

  1. Define the profile.
  2. Convert your RGB image to that profile. 3 Use the same CMYK values you have on the darkest places of the photo.

II. Work all on RGB

Especially if this print is going to be in a digital print.

III. Cut the box, and leave the background as a separated ink

This could be the case if you can use for example a special black ink as a 5th one. But probably will give you a dull black if you are not careful.

A variant of this is that you actually make the image blend using some transparency mode.


As I explained in the other answer I linked. I do not recommend that you use "old school" values of Rich black like c50m50 etc. This values should beeing given by the color profile.

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