How to build a scanning curve?

[Bruce Watson]

So, you're saying you begin your neg scanning sessions with no presets in the scanning software? It seems you're re-inventing the wheel each time.

You could say that. I say that I'm making an exact fit to my negative each time, which is what I think a good scanner operator should be doing.

If you want a series of B&W negatives to all exhibit a consistent density range, and the SBR varies widely as it often does for landscape work for example, you have to do the work somewhere. To get a given density range you do the work in developing (aka Zone System style expansion and/or contraction). I find it's simpler, easier, and gives me better results to do the work in setting the black and white points for each negative. With my scanner software, this takes less than a minute. But if you want to call it "re-inventing the wheel" I guess you can.

What this is, is a fairly large religious debate. There are people on both sides. Some say to profile scanners, some say that profiling scanners is a waste of time. I think that profiling scanners for trannies might be interesting, but that negatives vary too much to make profiles very useful.

In other words, I don't think "one size fits all" is the optimum way to get the most from a scanner when scanning negatives. But if it works for anyone else I say go for it. Whatever floats your boat.

[Bruce Watson]

I beg to differ, Bruce. Unless one is doing something seriously wrong, most of one person's negatives of a given filmstock, processed the same way, and exposed the same way will tend to have very close d-min, d-max and gamma. Making a scanning curve for this situation will get you 95% to what you need, with the last 5% being for variation in subject, mostly. I think it's worth doing for the time it will save you making the same corrections over and over.

Permission to differ granted. This isn't a dictatorship!

That said I have hundreds of well processed 5x4 Tri-X negatives that scan beautifully but that have a wide variance of density range. Then again, I quit doing any expansion and contraction development years ago. With scanning, it just isn't needed. What works is the extremely simple system of "expose for the shadows and let the highlights fall where they may."

I've tested until blood ran out my ears (well, maybe not quite that far). I understand how it works and why it works, but only because I've done the testing and proven it to myself.

[Kirk Gittings]

What works is the extremely simple system of "expose for the shadows and let the highlights fall where they may.

I did not see what the poster was scanning with but I cannot disgree more with this statement particularly with consumer flatbeds.. We have discussed this earlier so I won't repeat myself, but this lack of developement control of the highlights in my experience leads to real problems particularly with the consumer flatbeads, a bit less so with Imacons and even less so with drum scans. I have negatives just like this that nobody can scan properly because the highlight detail is so bunched up there is no way to separate it.

[Chris_Brown]

If you want a series of B&W negatives to all exhibit a consistent density range, and the SBR varies widely as it often does for landscape work for example, you have to do the work somewhere. To get a given density range you do the work in developing (aka Zone System style expansion and/or contraction). I find it's simpler, easier, and gives me better results to do the work in setting the black and white points for each negative. With my scanner software, this takes less than a minute. But if you want to call it "re-inventing the wheel" I guess you can.

Ah. I think you misunderstand me. I'm simply using my test film to give me starting input values, not final values.

Example:
Acquire a density reading (from the scanner) of film base + fog from a normally processed and exposed test sheet of B&W film. Save this reading in the scanning software. Then, for example, when an image comes up where FB+F is not close to the test reading, use that knowledge to set endpoints and midpoints accordingly.

What this is, is a fairly large religious debate. There are people on both sides. Some say to profile scanners, some say that profiling scanners is a waste of time. I think that profiling scanners for trannies might be interesting, but that negatives vary too much to make profiles very useful.

I think profiling a scanner for transparency work is worth the time and effort. My transparency scans from both an Imacon and Howtek drum scanner improved markedly after I began using the profiles correctly.

"Experts" say that profiling is a waste of time with color negatives, because the orange mask compresses blues so much. Okay, but I've not read how these experts approach the rest of the color workflow (not yet, anyway). Does the use of scanned negatives eliminate the need for a color-managed workflow? I don't think so, especially when an image is to be printed on any modern, ICC savvy inkjet printer. Color management helps attain accurate color and tonal reproduction, whether the image comes from negs or chromes.

So the question becomes: Where does one begin the color-managed workflow if the scanner profile is not used?

If I take an untagged image and assign an Adobe '98 profile to it (for example), I am saying that the colorspace of film negative+scan=Adobe '98. This is a path to poor color/tonal reproduction. Somehow, the colorspace of the neg+scan should be found to provide an accurate entry point into a color-managed workflow.

And this is where religion comes in. There's plenty of prayers while the clock spins, as a 2.5 Gigabyte file opens in Photoshop.

[Kirk Gittings]

With color negatives and Epson scanners with Silverfast, Michael Mutmansky and I have had reasonable success shooting a Macbeth chart, and scanning it in using one of SF canned film profiles that best approximates the Macbeth, tweaking the settings and saving that as a modified film profile. For myself I have found the need to create a series of these modified profiles depending on the lighting in the original scene I.E strobe lit interior, strobe fill interior with incandescent, strobe fill interior with flourescent, ambient light flourescent interior, exterior daylight, exterior twilight etc.etc. Though a simple daylight one really handles most variations adequately.

[Bruce Watson]

I have negatives just like this that nobody can scan properly because the highlight detail is so bunched up there is no way to separate it.

It doesn't sound to me like your problem negatives compared to mine are "just like this." It sounds like your problem negatives have a fair amount of image information off in the film's shoulder region which mine do not. If so I'll agree that they won't scan well. But then, nothing is going to salvage such negatives.

The underlying assumption I'm making is that one is using modern films and processing and hitting the exposure well so that the image runs from just above the film's toe up through the linear portion of the response curve. That is, "expose for the shadows" means the same thing in this discussion as it has meant for decades to Zone System practitioners.

I'm not talking about a slap-dash approach here. In order to expose the film correctly you still have to do your EI tests and your normal development tests (which for me gives me a Zone VIII density of around 1.0). Just like you would for the Zone System. Nothing I know of is going to let you off the hook of making a good exposure and having control of your process.

If you do that, you'll be fine. Modern B&W films seem to have rather long linear responses. "Expose for the shadows and let the highlights fall where they may" works fine for me with 5x4 Tri-X out to around 12 stops of SBR (a white magnolia blossom in full sun, midday in June). A more modern T-grain film would work just as well if not better. Negatives treated this way scan well on my old Epson 2450 consumer flatbed with VueScan. And they drum scan just beautifully.

[Henry Ambrose]

It seems this thread has wandered a good bit from the original question. If I remember correctly, the article that Stephen Sample referenced was about B&W negatives. So I assume that he is asking about B&W negative scanning. What I write about in this post is B&W negative scanning.

For work done in a controlled environment having a saved set of adjustments that is keyed to your film, processing, subject and lighting methods is a nice idea to make your scanning process faster. You get to start close to the best settings without having to re-set them each time you scan a different negative. I think what Steve Simmons meant in his article is literally a "curve" that you'd save. It depends on your software exactly how this is done. In Epson's PS plugin its in "Tone Correction" and you simply make adjustments in the curve window that will be shaped like an "s". (remember those film and paper curves in the darkroom?) When you get the preview to look like what you want, save that with a name that makes sense to you. Maybe "HP5 open shade" or "TMax100 studio" - something like that. Next time you scan HP5 shot in open shade you can select that tone curve from the pulldown menu. You'll be in the neighborhood of the right look and can fine tune from there.

As Bruce wrote, you're gonna have to set black and white points each time. You'll also have to be sure that the negative you expose and process contains densities that are within the capture range of -your- scanner. Anything outside of that range is lost. Kirk made note of this and it is vital that you follow this advice.

Now about color profiles - for B&W scanning there aren't any. Color work uses profiles to accurately translate color from device to device. "Coke can red" as seen by your scanner looks like "coke can red" on your monitor looks like "coke can red" on your print. Its that simple in concept. B&W does not use color profiles because there is no color to manage.

[Chris_Brown]

For myself I have found the need to create a series of these modified profiles depending on the lighting in the original scene I.E strobe lit interior, strobe fill interior with incandescent, strobe fill interior with flourescent, ambient light flourescent interior, exterior daylight, exterior twilight etc.etc. Though a simple daylight one really handles most variations adequately.

Just to clarify, when I refer to a "profile" I mean an ICC Color Profile generated from scanning an IT8 or HCT target transparency and processed through ICC Profile-generating software such as BasICColor Scan or Gretag-MacBeth ProfileMaker Photostudio.

I'm not referring to the saved input settings (endpoint, curve points, USM values, etc.) of scanner software.

[Chris_Brown]

Now about color profiles - for B&W scanning there aren't any.

What if you scan B&W negs in RGB mode?

[Henry Ambrose]

I am sure that Bruce & Kirk both know what they're about. But maybe it's easier stated in this most basic way: "you must get the scene information onto your film in a way that your scanner can see it".