help with grey balances and US Sheetfed Coated

[Ken S]

Hi there, I'm after some guidance on how to go about fixing a colour issue with our printers, a HP Z6100 and a Seiko 64S. I did a quick search of the forum and didn't manage to find anything that was relevant, apologies if this has been covered elsewhere.

At the moment I am using the US Sheetfed Coated colour space, as the larger gamut helps with Production House 7's spot colour matching. I am noticing that greys, even plain black greys are printing with magenta cast through them.

Our profiles are built by the folks who service our machines, and although calibrating the head alignment on the Seiko helped slightly, it is still present on both machines.

Would this be a problem with the media profiles or the colour space? Is there a better colourspace for wide format inkjets? Any advice would be appreciated.

Cheers!

 

[rich apollo]

Re: help with grey balances and US Sheetfed Coated

In Photoshop, if you create a document in Lab, fill with L=50 a=0 b=0, and then convert to US Sheetfed v2 you'll get:

a) 51C, 40M, 38Y, 6K with the absolute colorimetric rendering intent
b) 51C, 40M, 40Y, 7K with the relative colorimetric rendering intent

in other words Photoshop is throwing in a little extra cyan to maintain neutrality.

Going the other direction, create a CMYK document in the US Sheetfed v2 colorspace, fill with 50c, 40m, 40y, 0k, and convert to Lab.

a) Absolute colorimetric rendering intent yields L=53, a=0, b=2 (slightly yellow)
b) Relative colorimetric rendering intent yields L=55, a=1, b=1 (slightly red)

So, the US Sheetfed v2 profile does have a warm gray balance.

+Is there a better colourspace for wide format inkjets?+ That all depends on what you're going for. I'm not a fan of the US Sheetfed profiles.