U of S | Mailing List Archive | alt-photo-process-l | Re: gum curves

Re: gum curves

Oh, I get it, sorry, David. I misread your note completely, didn't understand you were referring to a quote from someone else (which I don't remember seeing). Yes, I agree completely, now that I see what you're saying.

I don't have any reason to think ChartThrob isn't a great method for generating curves, and I don't doubt the claims that expert printers in other processes are making that they are getting great curves for these other processes with it, even an improvement on curves they've generated using other methods. So I don't know why I can't make it work for me for gum. But I hope you'll try it so we can compare notes. (I suppose this discussion should probably go to hybridphoto to the ChartThrob thread).


On Oct 29, 2006, at 7:31 AM, davidhatton@totalise.co.uk wrote:

Hi Katherine,

what I meant was, what is wrong with this statement

..... At the very > least, a good curve would have been able to
get a close match to > the uncurved print (possibly with some changes in
exposure, > etc.).

Surely if a good curve should be a close match to the uncurved print then why oh why use a curve in the first place..

I haven't used this particular software yet although I have downloaded it. But, it looks as though the algorithm which makes the curve adjustment is moving the end points of the curve away from 0 and 255. Just a guess. I know though that you will savage this until the problem is identified ! Which is good for us :)



On Oct 28 2006, Katharine Thayer wrote:

Hi David,
Well, obviously something's wrong here, but that was my question,
what is it that's wrong? If you have an idea what's wrong, I wish
you'd tell me. I didn't run just the one curve, I've run a dozen of
them, and I've run them on different pigments, and they all come out
flat like that; none of them come close to the print as printed from
the inverted, uncurved file. I have an offlist correspondent working
on gum curves from ChartThrob; I hope by comparing notes we can
figure out what's going on, but like I said, if there's anyone here
who has already generated good gum curves from ChartThrob, I'd like
to hear about it. Kees, you sounded knowledgeable about ChartThrob;
have you generated gum curves from ChartThrob?

If I sound a bit frustrated, it's because I've wasted a lot of time
on this for nothing, but I can't seem to let it go because I'm a
person who always needs to understand why something is the way it is
and keeps worrying at it, like a dog with a bone, til I figure it
out. I wish I could just give it up as a lost cause and go back to
gum printing; I've got prints to finish.

On Oct 28, 2006, at 7:23 AM, davidhatton@totalise.co.uk wrote:

> Er..Isn't there something wrong here

..... At the very > least, a good curve would have been able to
get a close match to > the uncurved print (possibly with some changes in
exposure, > etc.).


David H