ChartThrob V1.01

[Vandorou]

Workflow with Chart Throb

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!

Hi Bjorke

I am about to install the script and try it. However I would be grateful if you could clarify the following points:

Photoshop Color Settings: what are the recommended color settings, especially RGB (ColorMatch or something else) and the gray gamma.

I presume that the positive of the calibration chart is inverted and printed as a negative on the substrate of choice (I am using Pictorico OHP)

What are the Photoshop and Printer settings (I am using a n Epson 2200)
Specifically in the Print with Preview window do you specify No color Management in the Color Handling?

In the Printer driver
i. What is the recommended Medium selection (Enhanced Matte, Premium Photo Glossy?)

ii. Recommended dpi? (1440 or 2880)

iii. High Speed on? Off?

Do you turn color management off at this point too?

When you scan the calibration target do you scan in color or in grayscale?
Once you develop a curve and you wish to apply it to your image at which point of the workflow do you apply the curve?

Specifically do you apply the curve to the positive of the B&W image and then invert or

Do you invert and then apply the curve?

Once you have printed your image, if you want to tweak the curve how do you go about it? And have you found it with your method that this is necessary?


Without even trying your method, I want to thank you on behalf of the community of users of digital negatives for going into the trouble of developing this method and making it available for free.

 

[mkochsch]

Colour Settings

Basically the rule with colour settings is just don't change them, remember you're working in monochrome anyway. But if you must know, I'll tell you mine, open the print preview:
Color Management [selected]
Print = Document (sRGB ICE...)
Options:
Color Handling = Let Photoshop Determine Colors
Printer Profile = SPR300 Premium Glossy (or whatever profile you want just don't change it or you'll have to recalibrate maybe)
Rendering Intent = Relative Colormetric, with Black Point checked.

Click "Print" go into your printer properties....

Now under "paper and quality" options:
Premium Glossy Photo Paper (or Luster perhaps, just don't change it!!)
Photo RPM (or your highest resolution)
Then select the paper size and turn on "Microweave"
High Speed OFF, if you want a tiny bit more quality and like waiting...

Use
ICM colour mode with "No Color Adjustment" selected.

Go into "Page Layout" and select "Mirror", this is so the ink side of the OHP is sitting on top of the emulsion (cyano, VDB, Silver etc)

Hit Print. Remember don't change the settings or you'll need to print a new stepwedge and curve...not the end of the world but a pain in the butt.

Apply the curve to the Positive in photoshop and then invert the adjusted image into negative and print (remember to make sure "mirror" is turned on).

Scan the calibration target in B&W on your scanner.

You may need to tweak the curve, hopefully not too much.

Good luck.

 

[Vandorou]

Colour Settings

Basically the rule with colour settings is just don't change them, remember you're working in monochrome anyway. But if you must know, I'll tell you mine, open the print preview:
Color Management [selected]
Print = Document (sRGB ICE...)
Options:
Color Handling = Let Photoshop Determine Colors
Printer Profile = SPR300 Premium Glossy (or whatever profile you want just don't change it or you'll have to recalibrate maybe)
Rendering Intent = Relative Colormetric, with Black Point checked.

Click "Print" go into your printer properties....

Now under "paper and quality" options:
Premium Glossy Photo Paper (or Luster perhaps, just don't change it!!)
Photo RPM (or your highest resolution)
Then select the paper size and turn on "Microweave"
High Speed OFF, if you want a tiny bit more quality and like waiting...

Use
ICM colour mode with "No Color Adjustment" selected.

Go into "Page Layout" and select "Mirror", this is so the ink side of the OHP is sitting on top of the emulsion (cyano, VDB, Silver etc)

Hit Print. Remember don't change the settings or you'll need to print a new stepwedge and curve...not the end of the world but a pain in the butt.

Apply the curve to the Positive in photoshop and then invert the adjusted image into negative and print (remember to make sure "mirror" is turned on).

Scan the calibration target in B&W on your scanner.

You may need to tweak the curve, hopefully not too much.

Good luck.

Thank you for the quick response. For the past 4 years, I have been making digital negatives using several methods so far.

When I was asking about color settings I was referring to the color settings in Photoshop that we access through the menu Edit Color Settings (in the Windows environment). Actually I was trying to figure out the color space. For example, Dan Burkholder recommends to set RGB to Color Match RGB etc.

In Photoshop's Print with Preview dialogue I have been selecting Color Management in the drop down menu and then under Options for Color Handling I have been selecting No Color Management.

The rest of the settings make sense, and given that I have developed curves for various processes with various methods, I will be happy to provide you my feedback once I use your system.

Regards,

maro

 

[mkochsch]

Don't thank me thank Kevin

The top ones were Photoshop settings...Not my system BTW, Kevin's system.
And like I said we're working in monochrome if you're talking "Working" space I choose Adobe 1998, but that's just my choice don't really know why anyone would use ColorMatch unless they had bought into it early on, it doesn't really matter for this stuff since we don't really need a colour managed workflow (ie. four-colour offset press work).

 

[bjorke]

I got font errors too

Wacky! I can only imagine that this is a Photshop bug because all text goes through the same function and every last bit of it is explictly set to "Arial." I have a hunch: is this a brand-new installation of CS2?

For some reason, when Photoshop is first installed the default font is set to 'Myriad Pro' -- even if you don't HAVE it. The solution is probably to open the character window. See 'Myriad Pro'? Set it to Arial or any other font that's actually present on your system, and see if the 'font not found' errors ever return.

 

[Vandorou]

Thanks directed to Kevin

The top ones were Photoshop settings...Not my system BTW, Kevin's system.
And like I said we're working in monochrome if you're talking "Working" space I choose Adobe 1998, but that's just my choice don't really know why anyone would use ColorMatch unless they had bought into it early on, it doesn't really matter for this stuff since we don't really need a colour managed workflow (ie. four-colour offset press work).

Thanks for the clarification.

Kevin, warm thanks directed to you.


Regards,

maro

 

[bjorke]

Photoshop Color Settings: what are the recommended color settings, especially RGB (ColorMatch or something else) and the gray gamma.

I presume that the positive of the calibration chart is inverted and printed as a negative on the substrate of choice (I am using Pictorico OHP)

What are the Photoshop and Printer settings (I am using a n Epson 2200)
Specifically in the Print with Preview window do you specify No color Management in the Color Handling?

In the Printer driver
i. What is the recommended Medium selection (Enhanced Matte, Premium Photo Glossy?)

ii. Recommended dpi? (1440 or 2880)

iii. High Speed on? Off?

Do you turn color management off at this point too?

When you scan the calibration target do you scan in color or in grayscale?
Once you develop a curve and you wish to apply it to your image at which point of the workflow do you apply the curve?

Specifically do you apply the curve to the positive of the B&W image and then invert or

Do you invert and then apply the curve?

Once you have printed your image, if you want to tweak the curve how do you go about it? And have you found it with your method that this is necessary?


Without even trying your method, I want to thank you on behalf of the community of users of digital negatives for going into the trouble of developing this method and making it available for free.

First, Maro, I hope you found the FAQ

You are probably doing a lot of the right things already. Basically, as long as your printing and color is repeatable (avoid automatic settings - "No Color Management" is a good idea), which it sounds like you're doing, then the other issues, such as dpi and high speed, will work themselves out. The analyzer will work with what you give it (though I'd recommend high speed off, for the sake of quality). Just use your pictorico setup as it already exists.

When you scan, you can scan in color or grayscale. Scanning in color will let the analyser try to correct for the base paper color.

 

[Keith Taylor]

Oh here's a neat trick. Use a "pre-selection" colour for your particular process and standard print time as you might do with one of those "other" digital negative systems and overlay the chartthrob grid using a colour layer in "screen" "mode" in the new layer dialog. You now should be looking at the ChartThrob step wedge as a nice green or orange pyro coloured negative...
Holy cow! You're now using colourised negatives! And all the advantages they give! ie. tuning the 0% square to be just dense enough to produce the white you want on the page for your highlight white point...more to follow...I think I can hear the sound of coffee being spit out...

I did the same last night, colourised it using my figures from PDN - although I've yet to print it. I was having trouble retaining tones in the print in the top two lines (whitest areas). It looks as though the tones in this new chart are more evenly spread out and should print with a greater range. Other than this, it's working great.

 

[sanfrancisconudes]

Wacky! I can only imagine that this is a Photshop bug because all text goes through the same function and every last bit of it is explictly set to "Arial." I have a hunch: is this a brand-new installation of CS2?

For some reason, when Photoshop is first installed the default font is set to 'Myriad Pro' -- even if you don't HAVE it. The solution is probably to open the character window. See 'Myriad Pro'? Set it to Arial or any other font that's actually present on your system, and see if the 'font not found' errors ever return.

It was set to Times New Roman. I set it to Arial in the character window, no change. This is with 1.05

If I hit cancel on the error, you can see the line is specifying Arial. So assuming the specification is done correctly that does indeed seem very strange.

 

[bjorke]

Adobe has already suggested a workaround -- folks with Myriad troubles may want to try version 1.06 (there is no other change from 1.05).

 

[sanfrancisconudes]

I went ahead and tried it and that did the trick!

 

[bjorke]

It looks as though the tones in this new chart are more evenly spread out and should print with a greater range. Other than this, it's working great.

The first sentence sounds good then the second... not? Can you elucidate a little?

BTW, I checked the wee thumbnails of prints from your website, lovely work! I'm most flattered that you think ChartThrob has promise.

KB

(PS: How did you end up in Mpls? Do you know this guy by any chance?
)

 

[mkochsch]

What are the Photoshop and Printer settings (I am using a n Epson 2200)
Specifically in the Print with Preview window do you specify “No color Management” in the Color Handling?

I was wrong on my original post here. Maybe wrong is too strong a word. You can (or could) be using "No Color Management" in most cases with ICM selected and with NCA also selected. The reason is that you probably won't be able to get enough ink density otherwise. I just did a print out of both ways and the "No Color Management" looks at least twice as dark (with a colourised negative mind you, not a "black ink" six ink-combined negative).
My Bad.

 

[Keith Taylor]

The first sentence sounds good then the second... not? Can you elucidate a little?

BTW, I checked the wee thumbnails of prints from your website, lovely work! I'm most flattered that you think ChartThrob has promise.

KB

(PS: How did you end up in Mpls? Do you know this guy by any chance?
)

Kevin,

My chart is printing (in palladium) with a nice range of tones except for the top two lightest bars. When I scan it and rerun ChartThrob, it suggests I increase the exposure to compensate, but the tones in the darker areas would block up and I'd have the same problem in reverse, right? (I must admit I'm pressured for time right now to run all the tests I'd like.) I did combine my PDN colours with it and that helped somewhat. I've stuck with the same workflow for ages now, but if I need to change the way I coat, then so be it, as I would love to get this to work. It has so much potential and the fact that you're devoting so much time to it and helping others for something you're not charging for is wonderful. Thanks.

My wife, who I met in London, is from Minneapolis and no, I don't know the person in the photo. I understand you lived in Minneapolis for some time, correct?

Cheers,
Keith.

 

[David A. Goldfarb]

Kevin,

My chart is printing (in palladium) with a nice range of tones except for the top two lightest bars.

When I was last looking through the drawers of Cy DeCosse prints at the John Stevenson gallery, one of the things I was most impressed by was the tonal separation you were getting in this range. Tom Sauerwein and I were discussing whether platinum lends itself to high key images, and John pulled out this beautiful high key platinum floral. Whatever you're doing, don't change a thing.

 

[bjorke]

My chart is printing (in palladium) with a nice range of tones except for the top two lightest bars. When I scan it and rerun ChartThrob, it suggests I increase the exposure to compensate, but the tones in the darker areas would block up and I'd have the same problem in reverse, right?

Ah, okay, I think I get it. Thanks it's tremendously helpful when great printers like yourself, Bill, David (everyone here, in fact) tell me what you're trying, needing, and expecting. A real gift to me, since my own printing skills are only so-so and my pt/pd experience rather thin. Thanks very much!

ChartThrob actually expects that the first print being scanned will have loss at both the highlight and shadow ends of the scale. That's why the sample chart runs from full 100% white to full 100% black -- there's an assumption that the computer file, and the resulting negative, will have a greater range than the contact print.

When ChartThrob looks at the scan of that printed chart, it looks for those blocked-up ranges and uses them to know where your print dmin and dmax are, then builds the curve so that subsequent pictures will hit those in a way that corresponds to the computer file's blacks and whites. The "Suggestion" box you saw is just the program telling you that you have more highlight loss than shadow loss, that it might be possible to get a little more range.

A good way to test the result (I can't believe I didn't put this in the instruction webpage, DUH!) is to take the original uncorrected chart, apply the generated curve to it, and print again. If things are working properly, then you should get a full range from the new curve-corrected chart.

(As for the guy in the snap, it's my buddy Dead Link Removed (or Dead Link Removed too) - among other things he shot all the big images that decorate the new Guthrie Theatre)

 

[BillSchwab]

Kevin,

Didn't want you to think I forgot. Got a heavy printing load right now and am having little time to give it another try. But, I did realize one thing. I have all color controls shut-off in my version of CS, but not in the new CS2. Once I changed that all looked different. Still haven't had the chance to do another test neg though. I'll let you know what happens. No sense in sending you test results of my mistakes.

B,

 

[Keith Taylor]

A good way to test the result (I can't believe I didn't put this in the instruction webpage, DUH!) is to take the original uncorrected chart, apply the generated curve to it, and print again. If things are working properly, then you should get a full range from the new curve-corrected chart.
(As for the guy in the snap, it's my buddy Dead Link Removed (or Dead Link Removed too) - among other things he shot all the big images that decorate the new Guthrie Theatre)

That makes complete sense, I'll give it a try. The new Guthrie is an amazing place and in fact I'm working on a neg of the building right now! I love the way they've incorporated your friend's photos into it.
Keith.

 

[sanfrancisconudes]

Well, I have some mixed results. I first printed a new cyanotype using the ChartThrob curve. The highlights were a bit blown out - not awful but definitely not where they should be.

I printed a Vandyke and it was just plain awful - very washed out.

However - I was never totally convinced I was getting a "good" scan, both in terms of the gamma being set correctly and in terms of the white point being set correctly.

I then decided to just take a photograph of the test charts just to see what would happen. I have zero idea if this even should be legit, but bear with me. I generated curves, which were qualitatively the same except towards the high end where they were substantially different. And applying them to a positive and just eyeballing the result, they both were much closer to what I would have expected. Basically if I swap between scanner curve and the photo curve you can see the problem areas are the ones that change and they change in the right direction.

I printed one negative for each process and hope to print them tomorrow. I had a little unrelated excitement where I broke my coating rod (sigh) but fabricated a new one in the lab today. It seems OK but we'll see. I'll post results when I have them.

In the meantime, obviously if the images are good I'll go with the new curves, but "should" this work? If you take a picture in RAW mode, and set the white and black point manually when converting them, should the resulting image be linear?

 

[sanfrancisconudes]

Judging from one wet print from each process the results look very nice - nice enough I made a test chart with platinum toned vandyke. More in a day or two when everything's dry...

 

[tsobota]

Kevin,

Yesterday I installed ChartThrob. It promptly bombed when analysing the scan of a print.

Looking at the code, I see the following in lines 874 and following:

pColour.rgb.red = findPV(doc.channels["Red"].histogram);

pColour.rgb.green = findPV(doc.channels["Green"].histogram);

pColour.rgb.blue = findPV(doc.channels["Blue"].histogram);


Sadly and surprisingly, this will not work in international versions of Photoshop. Some brilliant mind in Adobe decided to translate the color names, so for my Spanish version "Red", "Green" and "Blue" don't work, but instead "Rojo", "Verde" and "Azul" do.

So I just changed the color names to their indexes:

pColour.rgb.red = findPV(doc.channels[0].histogram);

pColour.rgb.green = findPV(doc.channels[1].histogram);

pColour.rgb.blue = findPV(doc.channels[2].histogram);


and it worked perfectly.

May I suggest this change ?

Tom Sobota
Madrid, Spain

 

[bjorke]

Wow Tom, that is pretty bent. I'm glad that you found a solution quickly, as I'm far from home and unable to do any ChartThrob tweaking this week.

I can't for now imagine why this fix wouldn't be fine, I'll check on localization of the color names too.

kb

 

[sanfrancisconudes]

Judging from one wet print from each process the results look very nice - nice enough I made a test chart with platinum toned vandyke. More in a day or two when everything's dry...

Just to follow up on that, I've made some more prints with each process and they all look very nice. I just printed negatives off of ChartThrob curves for platinum toned vandyke and Ziatype, I'll hopefully comment in a few days on how those went.

 

[Helen B]

I'd also like to thank Kevin for one of the most useful pieces of software for the creation of digital negatives, and for showing the potential for javascript in CS2.

Best,
Helen

 

[sanfrancisconudes]

Just to follow up on that, I've made some more prints with each process and they all look very nice. I just printed negatives off of ChartThrob curves for platinum toned vandyke and Ziatype, I'll hopefully comment in a few days on how those went.

Very happy with both, as it turns out!

If you want to see a Ziatype, look here: (warning - contains nudity) http://www.eljay.org/ebay/ziatype5.jpg