Gray... ugh....

I've printed out a few pages titled "Grayscale Printing" which I found in the Knowledge Base section of the Roland Website... sorry, I don't have a link but a search should yield the same results ...hope this helps.

JP

 

If the image is completely grayscale use the "Density Control Only" option for your Color Management Preset. This will prevent the rip from adding in other colors and will only use the black ink cartridge.

 

Don't you love using color theory... If you make a global correction in photoshop to neutralize the gray does it throw off all the other colors?

 

I am not color expert, but I think that "custom profiling" would help with this issue.

I have also seen customers adjust the "yellow" out of the gray (to get rid of the green tint) with good results.

 

Quite often our greys turn out on the greenish side also. It's very frustrating, but we've created a few 'custom' greys as we did for metallic gold. I guess when you're trying to match a color, it gets even harder. I always say.... Jeremy, figure this out.... and fast.

The only thing I can think of is.... can you utilize only the black channel and leave CMY out of it ??

 

Have you tried:

To adjust for global, if too blue add yellow
To adjust for global, if too red add cyan
To adjust for global, if too green add magenta
To adjust for global, if too yellow subtract yellow
To adjust for global, if too cyan subtract cyan
To adjust for global, if too magenta subtract magenta

For a local correction to your gradient you could probably just do a layer color adjustment. Or can you redo the gradient with target colors you know are a non-biased gray?

Can you print just the layer, also what rendering intent are you using in the rip.

 

Can you attach the file or a screenshot?

 

I've read that proper way to deal with a grayscale with color image is to build a pdf so the RIP can manipulate and color process each "section" of the file independently.

 

Where is the problematic area again?

 

What you're experiencing is called metamarism. The colors appear different under different light sources. The easiest way to cure this to to rebuild the existing profile to use less GCR. This will build your neutral using more black than cmy to make up the neutral colors.

I had the same thing doing a 4x8' RGB black and white print. Looked great under the daylight florescents, but turned a greenish shade under natural sunlight. I called up the data from the original targets and rebuilt the profile where the black generation curve had a 45 angle from 0-100 and it eliminated 98% of the color shift.

You may see a little more graininess in the highlight areas than usual since the black dots are much more visible than the CMY, but the reduction in metamarism will be worth it.

 

Thanks for that explanation! That'll be very good to know.

 

+1 for Rooster's comment. Depending on the profiling package you have you may have few, maybe no options to adjust UCR/GCR. In the nicer packages you can tweak quite a bit. For the cheap and quick fix, if possible try different media. Different coatings, OBAs, etc can affect metamerism.

Bryan

 

GCR is key to this problem along with having a good profile.

I recreate my profiles every other month as the weather changes... Sometimes I just relinerize and sometimes I start over from scratch. Everything adjust the print, temp, wind, position of the moon, solar flares, supernovas, ink drops, who's president.