Rainbow banding in drop shadows, light midtones.

[Andy_warp]

Wondering if anyone has ran into this issue. I built an icc profile through Onyx Production House. The solid pantone matches and CMYK photos are coming out extremely accurate. We are getting a rainbow banding in any type of solid to white gradient, or a very light color (ie: c=1,m=0,y=1,k=0)

We are seeing this even when we convert vector to raster, our current solution is to throw a little noise at it.

I'm hoping there is a more elegant solution out there...

Any comments or tips are welcome.

Thanks!

 

[genericname]

Welcome to the forum.

We use noise to get rid of pesky banding in gradients as well. Typically (unless it's a crappy customer supplied file), the banding is due to the ICC. Either too much of a difference between two readings on the same scale, or you've clipped your saturation of a particular colour too short, or started too high. The usual suggestion would be to re-profile, but if you've come up with a profile that performs well in other areas, a bit of noise now and then might be tolerable.

If you're getting it more in your black-white gradients as opposed to the coloured ones, be sure to save your files with PostScript level 3.

 

[P Wagner]

It sounds like you are experiencing gradient banding, and it is particularly noticeable in highlights. Have you attempted to print a file that is 16-bits (2-bpp) deep rather than 8-bit? Onyx 10 now supports files that use 16-bit color depth, and their primary benefit is more tonal gradations...256 discrete steps for 8-bit vs. 65,536 for 16-bit.

 

[Andy_warp]

We've tried running in 8bit, 16bit, smart 16bit...
I think the key is to build another profile...I just didn't want to hear that I had to scan/measure 1500 spot colors...twice, again!

 

[genericname]

We've tried running in 8bit, 16bit, smart 16bit...
I think the key is to build another profile...I just didn't want to hear that I had to scan/measure 1500 spot colors...twice, again!

You measure by line though, right? And 1500? Too low. Go for a pattern that prints more patches, with linearization, and be sure to scramble them.

 

[Andy_warp]

Thanks Genericname, I will give that a shot. Since I am profiling onto fabric, and within the limited dyesub gamut, any other tips? I think I did try a 2500 spot color scramble...I'll dig into it again!

 

[genericname]

...any other tips?

Not for the gradients, but for profiling with Onyx in general. When you've finished your profile, print an image with sharp, high-contrast shadows and highlights as a test. Look for clipping, and if you see dull spots where you should have rich Black (they may even look duller than the Gray that precedes them), open up your profile again, and enter a higher number for Black Ink Compensation, in the advanced ink limit area.

 

[Andy_warp]

We're still getting some pretty nasty clipping in our shadows. (really the color to shadow blends) I've dialed the black compensation all the way up, but to no avail. I guess I need to loosen my ink restrictions to gain adjustment via black compensation, right?

 

[Andy_warp]

I finally have a workable icc profile for my HP! It's a different machine now that it's linearized and profiled.

I thought an icc workflow was not possible with it (the option was grayed) but I finally figured out how to reconfigure the Onyx workflow options.

Our Mimaki and HP are now producing pretty nice color, but I think I need to get my eye one overhauled. It won't pass diagnostics now.

Has anyone out there had that done? X-Rite said $365.
Is this something that has to be done often?
Is there a more industrial grade instrument (that's NOT 10 grand)?

Our color testing per job is still dwindeling, and I'd like to keep improving my profiles.