Ben Goren wrote:
Is Photoshop's color engine really that bad, or is Argyll that good?
I think that Photoshops CMM is actually very high quality, but the difference is in using a device link, rather than linking the A2B and B2A tables of two profile. Photoshop doesn't support device links. Directly generating a device link from the A2B tables of the two profiles just cuts out all sorts of information loss and inaccuracy, as well as allowing a specific gamut mapping. The device gamut fills almost 100% of the A2B table, since it is indexed by device color value combinations. In contrast, the device gamut is lucky if it occupies 20-30% of the B2A table, since it is indexed by an L*a*b* cube, much of the volume of which are "imaginary" colors that aren't realizable in the real world. This means that for a given size, the B2A table is not able to hold as much information, and is simply "coarser". Another issue is that currently the Argyll B2A tables are probably not as good as they could be - there are some tricks that can probably improve their accuracy, and this is the project I am hoping to complete to release with V0.70.
I've wished for such on a couple occasions. I don't suppose you have any suggestions for one that works with a Canon i9900 on OS X (or a free Unix (preferably OpenBSD))? I sure haven't found any that cost less than four times as much as the printer that looked like they were any good....
That's the nature of such things. They are a more specialized product, and someone has to pay for such things to be developed and supported (I should know, since that's what I used to do !). Something like the Linux inkjet drivers offers the scope to do this (ie. Gutenprint), but it's not very well setup from the color point of view in my opinion (too much of the old style hand tweaked curves and equations, rather than modern instrument based calibration and profiling), so it mightn't give any better control or result than the built in RGB drivers. I have a project to write a driver for the Epson R1800 I own, but haven't found a chance to do much work on over the last 12 months. Such a driver might be adapted to other printers, if the print protocol is documented. Graeme Gill.