Sure, though I’m in the midst of doing customer work, so it’ll be at least a couple days before I have any of my film scanned in. In the meantime, you can look at my media page, it has a number of images shot on film and run through my process.
I just wanted to ask:I've added a new guide to my website for linearising digital camera RAW files, which can then be used with my CNMY set to invert negatives.
http://eigakai.ro/ps-action/cn-scan-inversion/converting-scans-made-with-digital-cameras
Not mere "semantics." Honesty. And btw, where do you see oblong pixels? Certainly not in 20X30 prints.
If you’re shooting black and white, once you white balance for your light source, you can treat each sensel directly as if it where monochrome (if you wrote your own code to do this) as you’re taking a picture of a frame that doesn’t contain any color information, so the only real color comes from your light source. Dial that out via white balance and you have effectively shot with no CFA. Doing that *very dramatically* increases the amount of visible fine detail in the photo. If you don’t do that, it’s debayered, then converted to BW, which eats a whole pile of potential resolution you’ve otherwise captured.
The more correct thing to do is digitize it into a positive image of the negative in raw samples, apply gain/multipliers to each channel until the film base plus fog is the same exposure, which will render it as light grey to white, then adjust the gamma of each channel so that it's response is linear relative to the exposure that made the density, then invert that. From there, if you did that correctly, a series of grey cards shot over a range of exposures from -5 EV to +7 EV in full stop increments should render grey at each point with little to no color shifts going on.
Should one really aim for true neutrals, though?
But if I wanted truly accurate colors, I suppose I'd just shoot digital and make a custom ICC profile with a ColorChecker. It seems to me that a lot of the "film look" is purposely inaccurate but pleasing color changes engineered by the good folks up in Rochester. Personally, I find this desirable and it's the reason I shoot color film instead of digital.
So, trying to think through how to achieve this, I get stuck. Obviously the film base + fog should be neutralized in the same way, but then what? I don't know what I should use as a reference for, say, the Portra look. A good RA4 print? Did these have true neutrals throughout the range?
Regardless of the emulsion, hues should render relatively accurately. Reds should be red, not orangish red, or pushing to magenta, skin tones should render as nice healthy skin tones not pushing to red or yellow, greens should be green, blues, blue, etc. the Macbeth chart is helpful for that. You don’t have to get it exactly on the money, but it does need to be reasonably close.
Saturation is a different animal, and is primarily where film differs from digital, for example, Ektar punches the daylights out of Portra in the saturation department and makes digital look like a skinny twig.
Is this really the case in practice, though? For instance, I've seen a lot of Ektar images where (white) people have red-pink skin, and I don't think they were improperly exposed or developed. It sure looks like this was an intentional tradeoff to improve how pleasing the color is for other subject matter. Or am I mistaking a change in saturation for a hue shift?
So is your claim that, in a Hue–Chrominance–Luminance model, the difference between Ektar and Portra comes down mostly to differences in how they render chrominance and not hue?
Is this really the case in practice, though? For instance, I've seen a lot of Ektar images where (white) people have red-pink skin, and I don't think they were improperly exposed or developed. It sure looks like this was an intentional tradeoff to improve how pleasing the color is for other subject matter. Or am I mistaking a change in saturation for a hue shift?
So is your claim that, in a Hue–Chrominance–Luminance model, the difference between Ektar and Portra comes down mostly to differences in how they render chrominance and not hue?
Macbeth charts of each Kodak emulsion except Portra 800 and the "new"
Oh, wow, this is great data. I'd love to buy you a beer and pick your brain about this stuff. But since you're on the other side of the country, I guess this will have to do.
First, are those charts corrected using your program? Maybe I'm again mistaking hue for saturation, or have undiagnosed abnormal color vision, but I have trouble characterizing the hues as all "pretty close to accurate." For instance, I see the background of the Ektar shot as grey, while the others all have some blue tint, and similarly the column of neutral patches on the left side of the chart in the Portra shot seems noticeably bluer than in the Ektar one. From your description I thought all the neutrals would be pretty much bang-on equal in the RGB channels, but I see variation between them. So it seems the residual variation after applying your "averaged" C-41 curve actually larger than I thought?
Second, why do you think the hue twists are necessary after correcting each channel? If the three primaries are additive and operate on separate layers, shouldn't it suffice to correct each channel individually? I think there are details of the development process that might involve interactions between the layers, but I'm not too sure.
Third, let me open a new can of worms and ask about going the other direction, trying to mimic film with digital. Suppose I take a digital capture with some Nikon DSLR and I decide that I want a "Portra look," for instance, where I mean capturing the general impression of the film and not a complete colorimetrically accurate replication. Assuming I'm happy it with how my raw converter rendered the hues, your analysis implies it would suffice to figure out how to selectively saturate and desaturate the various hues to create the look, right? Is the saturation change mostly a function of the hue, or does it vary in some complicated and nonlinear way depending on hue and lightness?
Should one really aim for true neutrals, though?
Yes, the only reason you don't get this is because your sensor is different to the paper that the negative is designed to be printed on. There is a few way to do this properly.
If your using a DSLR you will need to fudge it some how. I believe Adrian has one such method, that does very well.
I just wanted to ask:
"Do you have to share the name "Adrian" to be good at this stuff?
Adrian, not too different from what we do, but ours is very very much more detailed with dozens of exposures. We get H&D curves from these.
PE
I did a fair amount of shopping around and found an LED bulb that is 5000K and 90+ CRI and use that bulb to illuminate the paper print of this image. I then take a correctly exposed picture of the print (so far with a digital camera, film to come as soon as I get everything worked out) and use it to generate a hue twist look up table and saturation adjustment table
Yeah, the Macbeth chart is fine, but the patches are too far apart and aren't evenly spaced out (which leaves me with gaps where I could be a lot closer in hue if I had a waypoint there), and the saturation is too high, so it's hard to calculate how much saturation to pull out if a given hue angle is too saturated.
Hi, I think you're asking for trouble with that led. Since you shopped around so much, I presume you know what the spectral makeup of a white led looks like so I won't harp on that. I think you'd be a lot better off using electronic flash, and yeah, I know they dont generally come in at 5000K. (I presume your printer profile is based on D50, and this is why you selected that lamp?) If you think you HAVE to get closer to 5000K, you can do it with color temperature filters (look up mired shift). But I think you'd probably be fine with whatever the flash puts out with the camera white-balanced for it.
In another thread, I think, I referenced the Xrite ColorChecker SG. It's pretty pricey, north of $300, but it will help your problem. I've made hundreds of camera profiles using it or its predecessor, the Color Checker DC, which had a lot more test patches.
Here's an image from the B&H website:
Who is "We," and "Ours?"Adrian, not too different from what we do, but ours is very very much more detailed with dozens of exposures. We get H&D curves from these.
PE
Unless you're making images to match the color of a garment for a clothes ad, isn't color pretty much up to the beholder? When I scan Velvia 50 shots I've taken, I don;t try to match the original chrome slide but rather what looks pleasing to me. After all, unless you have both in front of you, who cares if there are differences? Negative film is even harder to match. So, why use the color charts? How do they help you?
Who is "We," and "Ours?"
So to return to the OP query, there is LR + NLP and then there is Adrian's Baconware... which may / may not use Simple Tools... or simply borrows the name. And then for us lesser mortals... we're kind of stuck.
Funny comment a while back: Why is it Vuescan and Silverfast never tied into DSLR scanned images? Clearly a lack of demand?
I've just received my MKI and it's companion hardware 'cause I'm getting tired of waiting on the Nikon LS8000 while it grinds away... and occasionally grinds to a halt. Repair costs aren't bad, just more frequent as the unit ages. And well, hope springs eternal... But I'm a CaptureOne user... so kind of seems like I'm SOL for this stuff.
I've not found the conversions from the DNG all that hard in CaptureOne, but they're do take some time... and so I may have to switch back to LR. Oh well.
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