Re: [Gimp-print-devel] Halftoning algorithms

[Karl H. K. <kh...@kh...>]

On Mon, Mar 06, 2000 at 06:12:53AM -0800, Raph Levien wrote:
> This message was sent from Geocrawler.com by "Raph Levien" <ra...@ac...>

=2E.. wait a minute, I know you! ... or at least I know what you
did last summer :-)

You were involved in gcmm, is this correct? I downloaded the last
snapshot this week to see if I can use it in SANE. The print plugin
could also benefit from some ICC routines to do the RGB->CMYK=20
transformation. I noticed that the project is pretty dormant since
last year, is anybody using it? Are you planning to work on it any
time soon?

But now back to our actual subject:

>    I've done quite a bit of work over the years on
> screening algorithms. I'm trying to push some of
> them for commercial licensing, see
> http://www.artofcode.com/eventone/ for details.

This looks very interesting. You are however talking
about multiple algorithms and you want to push some
of them... Are there any good ones left that are=20
and will stay free? :-)

>=20
>    To this end, I've been building a testbed that
> includes RGB->CMYK conversion and actual device

I was looking into doing teh RGB->CMYK conversion based
on ICC profiles. I just started reading about all things
related to CMS systems. Can you either provide some=20
input or direct me to good literature. I was thinking
about getting the Giorgianni/Madden book.=20

>    Not to overstate things, but the quality is
> incredible. It is dramatically better than the gs
> and gimp-print drivers, and, while I haven't done
> serious comparison yet with the bundled windows
> drivers, my guess is that it's comparable or
> slightly better.

I did some one to one comparison of the print plugin and
the Windows driver on the weekend, and even though the
quality of Robert's code is quite good, it's still far=20
from what I can get under Windows. (Can I admit here=20
that I have vmware running just to print stuff?)

>    I want to do the right thing in terms of
> releasing this code as open source, but I'm moving
> cautiously on that right now. There are a number
> of companies who have stated that they're working
> on improving print quality (the VA - HP alliance
> and Corel come to mind), and I'd like to see if
> they can fund the project.

You hold the patent to the algorighms (at least that's
what I understand from reading your page), so you=20
should be free to license the stuff to open source
projects free of charge, but still charge for other
licensees. As Eric already mentioned, there is no
better resumee for you than to put the code out in
the open and use a project like Gimp or GhostScript
as "bill board" for the algorithm.

>=20
>    In the meantime, I want to keep you guys in the
> loop. I am happy to give you guys the code to play
> around with, with the understanding that it is not
> yet free software, but will be at some date in the
> not too distant future. I talked to Peter Deutsch
> a few days ago, so he's up to speed as well.

I am with Eric here: Don't make it available until
it's really free. If somebody walks up to you=20
tomorrow and offeres you a deal that's just too good
to resist for the exclusive rights we would have a=20
problem.=20

>=20
>    I've learned a lot by reading the gimp-print
> code. I think you might enjoy reading through my
> code. Among other things, I have _much_ simpler
> code for microweaving. At the moment, the code is
> specialized for the stc600 and needs to be
> parameterized a bit, but the entire Epson driver
> is 236 lines of code.

The weaving code is IMHO not the problem. It is now stable
enough to even work on my STC740 :-) So I would not tamper
with it. If you can offer something in regards to the=20
error diffusion algorighm, this would help the quality of=20
the plugin more than anything else.=20

I hope we can work something out together. I'm looking
forward to hearing some great news from you,

Karl Heinz

--=20
Karl Heinz Kremer                                      kh...@kh...
                                                http://www.khk.net