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Trying to figure out how to print this image of a motorcycle so that it doesn't have this halo effect (if thats what its called) when printed on top of 100% K. Tried a few different things but nothing seems to make much of a difference and it just clearly sits on top of the black without blending at all.
The black in the bike needs to match the background black.
If the background is 100% K, the bike needs to also be 100%k.
If the background is 40C0M0Y100K, then the bike needs to be 40C0M0Y100K
It may be easier to just add a transparency gradient to the bottom of the bike rather than adding a black gradient.
1. You need to edit your bike image in RGB. Adjust the levels so you have what is called a "black point" on the tires. This is one spot (or a zone) that is r0g0b0.
As you will probably darken the overall bike you probably need to duplicate the layer and use some gradient between the dark part and the light part. But that is another issue.
You can confirm this is black looking at the histogram or levels.
2. After this, you need to define the correct color profile in which your print should be. If it is a digital print you can use Fogra 39 for example, but for offset, you probably need another, like Swop2 or Fogra 27. Ask your provider.
3. When you convert the image to CMYK it will give you specific CMYK values of this dark RGB black to that specific conversion. For example, the values I know are c75m68y37k90 which are from using the Swop 2 profile.
4. These are the exact values you need to use in your black swatch. Not k100% alone or any empirical value like c50%k100%.
As the tires are grayish there is a chance your program is converting the r0g0b0 to only k100% This is only needed in a strange case where you have a black text.
P.S. (Do not use c100m100y100k100)
This answer was originally to be a response to your comment, but it would have been too long and it does (I hope) help answer the question.
I actually tried a gradient feather in InDesign on the bottom and it didn't seem to affect the printed appearance of the bike, which surprised me a little because I thought it would get rid of that grayish appearance at least a little. I'll try it again though. – alxmntrvl 9 hours ago
I recall discovering many years ago working as a printer that with Adobe InDesign CS5, a color image or color layout element placed in conjunction with (overlapping) a black border or text or background design would alter the printing (CMYK) of the black to be CMYK instead of just K. Regardless of transparency effects.
In other words, the blending of a transparent CMYK element with a plain black line or piece of text produced a black that was printed (on the Xerox 700 Digital Color Press I was using) with four colors of toner. This made that part of the line or text look glossy, in contrast to the portion outside of the color blended area.
From your photo, it appears that the bottom part of the motorcycle is being printed as a process color (CMYK, probably 100% of all four) and the rest of the black background is just black ink (K). (This is the reverse of what Rafael's answer describes, but that's what it looks like to me. I worked as a printer as well as graphic designer, but I could be wrong.) :)
One possible solution is to make the entire black section (the background) CMYK black. I've used that solution, but I prefer the other solution:
The other is to force that part of the image to grayscale so InDesign won't print it with CMYK but just with K. The quick way I would use to do this would be to:
When you print the resulting file the halo should be gone. (It's been a while and this was on an older version of InDesign, so please let me know how it goes.)
