Idea: Online Curve Calculator

mkochsch · May 7, 2007

Would anyone be interested in an "online" curve calculator. I've been toying with the idea and just recently thought it might be an interesting way to manually calculate "tricky" curves. I'm thinking either a java applet or active x based Excel table that allows the user to punch in 14 sets of data.

~m

roy · May 7, 2007

Might help me ! As a darkroom black & white worker who has never tried to use Photoshop and is about to delve into the mysteries of digital negative making for alt. processes, I find all this 'colour array' chat way above my head. Obviously I am going to have to get stuck into some sort of tutorial.
I do find it all sort of informative as one of the first things I am going to have to do is to get a printer to work alongside my document printer.

MVNelson · May 7, 2007

sounds interesting...will it compliment Array/ChartThrob or replace or the process is not related...?

Miles

mkochsch · May 7, 2007

roy said:
Might help me ! As a darkroom black & white worker who has never tried to use Photoshop and is about to delve into the mysteries of digital negative making for alt. processes, I find all this 'colour array' chat way above my head. Obviously I am going to have to get stuck into some sort of tutorial.
I do find it all sort of informative as one of the first things I am going to have to do is to get a printer to work alongside my document printer.

I was thinking of people like you Roy and people who don't use Photoshop CS2 also. I was thinking it could also have "sample" data so users could see how different data sets affect the curve. Don't fret about the colour array stuff, it's similar to using variable contrast black & white paper if that helps. Except because we don't have a projector/enlarger in alternative photography we have to colour the negative instead of putting a filter in the holder under the enlarger. It's really that simple.

~m

mkochsch · May 7, 2007

Mvnelson said:
sounds interesting...will it compliment Array/ChartThrob or replace or the process is not related...?

Miles

It's a slower method for sure, but sometimes that's good. I'm thinking it compliments ChartThrob because you'll be able to compare the results of the two systems. Also, it shows you the actual brightness values so there becomes some familiarity with the numbers....I'm working on the page as we speak...it's hard to say which is the best method (java or activeX) Can Mac users run ActiveX'es on IE? Also I've found some java code that writes the ACV curve format so there's the possibility at some point it can spit out the results as an ACV file too.

~m

MVNelson · May 7, 2007

Java is cool, cleaner code, much better multi-platform wise, Linux likes it. Active -x is closed and much more sensitive not only to platform but to hardware varience within platforms...

miles

dwross2 · May 7, 2007

mkochsch said:
Would anyone be interested in an "online" curve calculator. I've been toying with the idea and just recently thought it might be an interesting way to manually calculate "tricky" curves. I'm thinking either a java applet or active x based Excel table that allows the user to punch in 14 sets of data.

~m

Hi

Could you give a short outline of the basic idea? (and system/info requirements) Talk about 'over the head'!

Thank you,
Denise

mkochsch · May 7, 2007

dwross said:
Hi

Could you give a short outline of the basic idea? (and system/info requirements) Talk about 'over the head'!

Thank you,
Denise

OK. We need to apply a (PhotoShop) curve file to the negative when using an inkjet printer as the output device. Currently users either calculate curves with graph paper using the values obtained by printing a 101-Step Wedge or a spreadsheet or with ChartThrob. What we're noting is the difference between the values in the step wedge generated on the computer and the values returned after being contact printed to the process. The first set of values (on the computer) are the "input" values (the ideal) and the second set are the "output" values (what you get in reality print to paper). If what you asked for and what you got back was the same there would be no need to apply the curve. You would have a "linear" relationship. Ten percent grey would print to ten per cent grey, 20 per cent would print exactly 20 per cent....etc..This rarely happens. The curve purpose is to "map" the input values so that when the negative is contact printed the inputs land on the intended output values. For example, an input value of 50 percent may have to be mapped to 35 per cent in the negative to print at 50 per cent on the exposed paper. After you plot out the input and actual output values from a 101-step wedge by hand a few times you will begin to see how it works a little better.
~m

Katharine Thayer · May 7, 2007

mkochsch said:
Would anyone be interested in an "online" curve calculator. I've been toying with the idea and just recently thought it might be an interesting way to manually calculate "tricky" curves. I'm thinking either a java applet or active x based Excel table that allows the user to punch in 14 sets of data.

~m

Yes, I think that might be useful, and welcome, although I haven't yet come to a point where I need more than ChartThrob.
kt

dwross2 · May 7, 2007

Thank you. That's actually quite clear. My eyes didn't glaze once. I can see where it would cut down on my trial and error costs. That alone makes it a worthy venture.

donbga · May 7, 2007

mkochsch said:
Would anyone be interested in an "online" curve calculator. I've been toying with the idea and just recently thought it might be an interesting way to manually calculate "tricky" curves. I'm thinking either a java applet or active x based Excel table that allows the user to punch in 14 sets of data.

~m

FWIW, Huntington Witherill has a downloadable B&W calibration system for the Mac or PC on his web site. I've not used it but it may be worth taking a gander at.

Dead Link Removed

Don Bryant

Kerik · May 7, 2007

mkochsch - Sounds like a great idea.

mkochsch · May 7, 2007

Yes that's the kind of thing except it doesn't have to deal with density only relative density to the digital negative....and as a online app.

~m

MVNelson · May 7, 2007

I told you to write the book........Very good explanation

Idea: Online Curve Calculator

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