ChartThrob V1.01

[Bjorke]

Click "Save Link As...." here to get a new version of ChartThrob.

What it is: a Photoshop script for CS2+ -- install it in your CS2/Presets/Scripts directory and restart Photoshop. It will appear in the File->Scripts menu.

What it does: It creates (positive) grayscale charts. If you print these charts via digital contact printing (or any other process), you can scan the results, run ChartThrob a second time to analyze the scan, and it will automatically create a Photoshop "Curves" adjustment profile that you can apply to digital positives before printing to ensure that they get the full range of available grays from your wet process.

Caveats: your process must be consistent between prints, and the tones should not vary wildly depending on location on the print (that is, 50% gray should always be 50% gray whether it's in the center, corner, bottom, top, etc)

Feedback most appreciated!

[Bjorke]

BTW, here are the changes from the previous version:

1. In some cases, slight numeric errors (eight bits can only hold so much!) would cause some colors to be calculated as slightly brighter than Photoshop's permitted color range, which would cause a script error. These errors are now correctly avoided. This occured principally in circumstances where the print had been made on very dark or unevenly-toned paper, or the original chart had been accidentally printed as a negative (it's meant to be a positive).
2. The chart text and 'Help' dialog box have been modified to make it clear which images and prints are positives, and which are negatives
3. The ChartThrob main dialog box was upgraded for clarity
4. A DPI setting for new charts was added, though it's a bit superfluous -- you can always resize the chart as you see fit from the Photoshop 'image size' dialog, because what matters are the color values of the patches -- not the pixel counts
5. When analyzing scanned prints of charts, ChartThrob now lets you know where in the grayscale range it found the dmin and dmax of your scan. Generally, if these are at the extremes of the chart range, then you may be served by adjusting your exposure to get a wider range of tones

[David A. Goldfarb]

Sounds very cool. I'll be interested to hear how it works for those who are printing from digital negs.

[tom_micklin]

Will this work in Photoshop CS, or is it just for CS2?
Thanks,
Tom

[Bjorke]

I have updated to Version 1.02 - same link as above.

ChartThrob uses the 'jsx' script rather than plain 'js' -- so CS2 is required, since some of the UI elements are not present in CS (or PS-7).

The latest revs correct some weirdness at the upper or lower ends of the scale (particularly when the scanned exposure range goes past either end of the scale due to underexposure or overexposure), improved layouts for the dialogs and more constructive online help.

kb

BTW, it's funnest to run the script if the Histogram panel is exposed.

[David A. Goldfarb]

I don't make digital negs or own any kind of photo quality printer, but just for the sake of seeing how this script works, I ran it using my HP5L, and heck, ya know, it does what it's supposed to do. Of course the result in this particular case still looks like something off a crappy desktop laser printer, but with the right process, I can see how this would be a very handy thing. Well done, Kevin!

[ann]

ok, i take david's word, but how does one download this to even test it out.

all i see is code when i click on the "here".

[Bjorke]

Originally Posted by ann

ok, i take david's word, but how does one download this to even test it out.

all i see is code when i click on the "here".

I've made a wee page for it: ChartThrob Instructions and FAQ.

Basically, right-click on the ChartThrob code link and choose "Save As..." or "Save Link As..." and save it as ChartThrob.jsx.

Or follow the more detailed instructions I just mentioned.

cheers,
KB

[Digidurst]

Hey, just curious to know... is there a particular color space you suggest for this? What about printer settings? Thanks!

[SanFranciscoNudes]

Very cool! I printed a test negative and will try it out on new cyanotype first...