darkroom equivalent of "curves" in PS?

[stradibarrius]

When I scan a negative and then apply "curves" or "levels" via PS, what is the darkroom equivalent? I always feel like the software is doing something that can't be done in the darkroom.

[djdister]

When I scan a negative and then apply "curves" or "levels" via PS, what is the darkroom equivalent? I always feel like the software is
doing something that can't be done in the darkroom.

The rough equivalent in the darkroom is manipulating the image contrast, tonal range, and color balance.

[jp]

Lotsa stuff you can do with curves in photoshop.
As mentioned. contrast, tonal range, color balance
you can also solarize, posterize, split contrast, fog/pre-flash, underdevelop, underexpose, overexpose, and all sorts of craziness with curves

[paulr]

I think of the curves tool as the rough equivalent of everything that goes on in the darkroom.

I spent years figuring out how to get the tonal curve I wanted, through choice of paper, adjustments in developer formulas and development, etc... Curves let's you just draw the shape you want.

[Jim Noel]

Curves are based on the Characteristic Curve of the film and paper. They are controlled in film photography by exposure and development first, and then altered in many ways including burning, dodging, bleaching, toning, and several other techniques.

[lecarp]

Film curves have been around a lot longer than Photoshop. Most legitimate tasks in Photoshop mimic real Photography.

[stradibarrius]

111926Here is an example. one obviously is the negative scan and only resized for the web. The other has been worked in PS with curves, burn etc.
Would you have developed longer?, changed exposure somehow?, your thoughts and suggestion please.
This 4x5 TMAX processed in Pyrocat HD 1+1.5+100 for 13mn.

[Jim Noel]

111926Here is an example. one obviously is the negative scan and only resized for the web. The other has been worked in PS with curves, burn etc.
Would you have developed longer?, changed exposure somehow?, your thoughts and suggestion please.
This 4x5 TMAX processed in Pyrocat HD 1+1.5+100 for 13mn.
It would be easier to analyze the negative, but based on the second image I would say your negative is significantly underdeveloped. If our goal is a print resembling the first image, a film with more inherent contrast like FP4+ would be better.

[paulr]

111926Here is an example. one obviously is the negative scan and only resized for the web. The other has been worked in PS with curves, burn etc.
Would you have developed longer?, changed exposure somehow?, your thoughts and suggestion please.
This 4x5 TMAX processed in Pyrocat HD 1+1.5+100 for 13mn.

The raw scan just shows a linear representation of the negative's values. You don't see that in a darkroom print, because gelatin silver paper has an S-shaped tonal curve. This means that photo paper is more or less linear in the midtones, but compressed the hightlights and shadows.

The curve you applied in photoshop was s-shaped. I've attached a curve I made that fairly closely mimmicks your results. You can see that it increases the overall contrsast (by bringing the black and white points in toward the center), and compresses the highlights and shadows the way that a typical photographic paper would.

I don't think your negative or scan has any problems. The scan is relatively low contrast, and you have plenty of detail in the highlights and the shadows. This is what you want: lots of information to work with.

It's perfectly normal to have to apply a curve. If you came up with a negative process that didn't require one, you'd never be able to get a decent darkroom print. Photo paper would apply its own intrinsic curve, and you'd have to fight against it. With the neg and scan that you've shown, you could either print in the darkroom, or get a good digital file with very little work.

[Drew Wiley]

It's called masking, and has been around forever in all kinds of flavors. But ya gotta learn all your basic development and contrast controls first, and then decide if
you need anything advanced at all. With excellent variable-contrast papers on the market, probably not. But when it comes to printing color in the darkroom, that's
a different story...

[stradibarrius]

Thanks Paul for your explanation, it makes sense. When you look at the actual negative on the light box there is all the detail present. I didn't realize that gelatin silver paper had an "S" type response. The reason I wound up with an "S" shaped curve from my scan was because it looked "right" to me???

[bob carnie]

Depending on the subject matter your curve shape can be varied and quite different ..
An S curve in PS would work well with a subject with lots of mid tone, but would not look great on a high key subject or a low key subject.



Thanks Paul for your explanation, it makes sense. When you look at the actual negative on the light box there is all the detail present. I didn't realize that gelatin silver paper had an "S" type response. The reason I wound up with an "S" shaped curve from my scan was because it looked "right" to me???

[Kirk Gittings]

Film curves have been around a lot longer than Photoshop. Most legitimate tasks in Photoshop mimic real Photography.

What is a legitimate task?

[paulr]

The reason I wound up with an "S" shaped curve from my scan was because it looked "right" to me???

Absolutely. And it's not surprising; all the silver prints you've seen were printed on materials with an s-shaped curve. It's what traditional black and white photographs look like.

But as Bob points out, it's not your only choice. Just a useful starting point.

Some processes like platinum and palladium have a much less pronounced curve ... that's why they have a much more open-shadowed look, closer to your raw scan.

[paulr]

What is a legitimate task?

Not counterfeiting money.

[Kirk Gittings]

Not counterfeiting money.

:)

[Ken Lee]

http://www.kenleegallery.com/images/forum/PSCurve2.jpg http://www.kenleegallery.com/images/forum/PSCurve3.jpg http://www.kenleegallery.com/images/forum/PSCurve1.jpg

"I always feel like the software is doing something that can't be done in the darkroom."

Not always, but... sometimes :)

Perhaps your question points to the fact that unlike a simple change in paper grade or contrast filter, some curve adjustments can be non-trivial - like the ones shown above.

Please correct me if I'm wrong, but making similar corrections via changes in paper grade, exposure and development would be a challenge, while taking only seconds in an editing tool.

I'm not saying that we should make these kind of adjustments, only answering the OP's question. I try to avoid "heroic" adjustments (and subjects which demand them), but they can be used to rescue damaged or vintage photos and for unusual effects.

[BetterSense]

http://www.kenleegallery.com/images/forum/PSCurve2.jpg http://www.kenleegallery.com/images/forum/PSCurve3.jpg http://www.kenleegallery.com/images/forum/PSCurve1.jpg

"I always feel like the software is doing something that can't be done in the darkroom."

Not always, but... sometimes :)

Perhaps your question points to the fact that unlike a simple change in paper grade or contrast filter, some curve adjustments can be non-trivial - like the ones shown above.

Please correct me if I'm wrong, but making similar corrections via changes in paper grade, exposure and development would be a challenge, while taking only seconds in an editing tool.

I'm not saying that we should make these kind of adjustments, only answering the OP's question. I try to avoid "heroic" adjustments (and subjects which demand them), but they can be used to rescue damaged and vintage photos, and for unusual effects.

The distinguishing feature of digital imaging is that the data can be manipulated to look like anything at all, including but not limited to resembling a photograph. I think that digital tools are supremely capable of mimicing every type of image manipulation done in a darkroom. There is no limit.

[NickyLai]

This PDF file with photo example vs curve line and explanation may provide some reference:

A quote copy and paste from the PDF:

quote:

The Better Light Processing Curves are meant
as a starting point for varied photographic appli-
cations. They will provide results similar to the
combined effects of a selected film emulsion
and processing method plus the subsequent
manipulation of tones when scanning the film to
digital information.

:unquote

Link to document:

http://www.betterlight.com/downloads/Manuals-Tutorials/tonecurve_samples5.pdf

[Drew Wiley]

Different kinds of film and developer combinaton have different curves to begin with, just as with papers themselves. The main idea is to pick a discrete set of combinations which appeal to you personally, then if necessary, tweak something only if the ordinary techniques don't work. Ken's diagrams show examples of
gross curve manipulations which can be done in PS which are really overboard with respect to anything likely to be needed in actual darkroom work, and probably in
any "realistic" form of printing from film. Basically, what normally transpires would equate to just a little bending to the toe or heel of the curve a tad, either exaggerating or minimizing the "S" of the curve at times. Much easier to actually do in a darkroom than to try to explain using metaphors from a completely different
workflow of printing.

[paulr]

...There is no limit.

Or maybe there are no theoretical limits. In practice, some things are so hard to do that we tend to avoid them. Especially when working with color. It's very difficult to use photoshop to match certain kinds of color renditions that can be achieved with raw processing tools. And it's very difficult to get any digital tools to match the color rendering of certain color films, especially the greens of folliage.

I personally don't want my pictures to look like Velvia, but photogrphers trying to get the same palette with digital tools have a hard time ... especially with leaves and grass.

We more often hear the opposite argument ... that all the stuff we do in photoshop is possible in the darkroom. It is, and there's evidence going back to the mid 19th century. The question again is difficulty. Something that took hours for a studio full of trained brush artists can be done in minutes by anyone with a basic command of photoshop. What was previously a special project can now be part of a normal workflow.

[Andrew O'Neill]

Things I do to manipulate the film curve in the darkroom is choice of developer, dilution, over-exposure (in the field) under-development, bleach and redevelopment. Out in the field, pre-exposure...
For your cemetery image, I would probably use pre-exposure.

[gubaguba]

Curves per se doesn't exist in the darkroom. Back in the day we would use a sensitometer and plot the density response curve of films and papers. This is what photoshop curves is based on. However photoshop curve is not a curve at all but a flat line response, it curves when I change it. In the darkroom these curves (density) can be changed by changing exposure, developers, developer times, using toners. All of these need to be tested to be used properly.

[Drew Wiley]

Plotting densitometer curves is still a very useful skill when doing advanced color printing. I rarely bother in black and white work.