Hi Sandy
--
I'm reluctant to keep this thread going but I think it worth pointing out a couple things.
ABW has two issues that are important:
1) the obvious one -- there are multiple "dark/light" options -- darkest,darker,dark,normal,light
so you can pick different "curve" targets when printing. Darker is the default.
2) the hidden one -- in general the printing is trying to match the L-values of the target --
using either the real embedded profile or the assumed one -- its pretty likely to be matching
GG2.2 or sRGB both of which are darker in the shadow area compared to linear.
(this is true unless App you are using to print happens to have No CM with ABW)
I also think ABW is designed to match these popular editing spaces.
Roy
On Sun, Aug 7, 2016 at 4:45 PM, sanking@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
I *think* there was an earlier comment in this thread from Eugene to the effect that ABW wasn't that far from linear. That's not what I found when I've measured it, not by a very long shot. I don't understand what Epson were trying to achieve when they designed its behaviour. But there are a lot of people out there who think it's wonderful. I guess you can adapt to anything.
I am a bit late in replying, but my experience in comparing ABW with QTR is the same as that of Brian, i.e. ABS is far from linear.
I compared step wedges printed with the Epson 7880 using ABW and QTR on Epson Enhanced matte, both with Warm tone selected. I then scanned the step wedges with an iOne and ran the data through QTR Linearize Data. As you can see, the QTR print is almost perfectly linear and requires no correction, whereas the ABW print needs a significant curve to make the output completely linear.
The A and B values are so similar it looks to me that both ABC-Warm and QTR-Warm are using only all gray inks, MK, LK and LLK.
I posted the QTR Linearize .out data in the zzMisc folder in the Files section if anyone is interested in looking at them.
Sandy