Petteri's Pontifications
My musings about photography, mostly.
RSS feed
Simulating Film Effects with Curves

Simulating Film Effects with Curves

I know I'm not exactly inventing the wheel here, but I have been treading one moderately well-trodden path recently: attempting to recreate the look of a few types of film I know and like. The method I chose was the simplest possible: attempting to create a set of Photoshop curves I could use to give photos these looks with a minimum of fuss. I don't even pretend to aim for accuracy. It wouldn't really help much in any case, since the photos on which I want to use them come from a variety of cameras and converters, and therefore no single method would be applicable to all of them. I haven't done any side-by-side comparison shots of film versus digital, although I have compared my results against some scans I've made previously -- and nope, they're not exact matches, nor, I think, will they ever be. But they do go at least a part of the way towards recreating the feel I used to create by my choice of film stock.

Emma Vaaen. Canon EF 50/1.8 on EOS-5D. Straight conversion with Raw Shooter Premium. To me, this has the "Provia feel" straight out of the box. Sometimes it goes like that...

One of the more important creative choices a photographer had the pleasure of making back in film days was choosing what kind of film to shoot. Slow, saturated, contrasty slide film gives a completely different feel to a picture than fast, grainy, high-latitude color negative film. Different brands and makes of slide give their own flavor to pictures: Provia rendering scenes in a cool, low-key, translucent way, Kodachrome in a rich, deep, colorful way, and Velvia in a completely over-the-top almost cartoonish way. When the choice was well made, the result just looked so wonderfully right that it would almost make a grown man weep... and when the choice was wrong, it could mean not getting the picture at all, or jumping through any number of hoops to getting something remotely acceptable out of the exposed frame.

Tyre Cat. Canon FD 50/1.4 SSC on Fujichrome Provia 100F.

Those of us who transitioned to digital no longer have much choice in capture medium. We're pretty much stuck with whatever happens to sit inside our cameras, and our choice of camera is to a great degree dictated by its picture-taking characteristics than its imaging characteristics. Some of us have slow, big, high-resolution cameras for big prints and fast, smaller, lower-resolution cameras for situational shooting, with perhaps a few tiny cameras for take-anywhere shooting, but very few have dedicated portrait cameras, landscape cameras, sports cameras, nighttime cameras, architecture cameras, black-and-white cameras, street cameras, photojournalism cameras, like they used to have dedicated films for each of these missions, and more. Instead, the creative choice of film stock has moved to the digital darkroom. Digital capture can give us a starting point that's more or less neutral and lends itself to being massaged into any of the looks and feels associated with these types of photography. The only trouble is getting there, especially in a repeatable or consistent way.

Autumn reflections. Rollei AF-M 35 on Kodak Portra 400NC.

The theory

Films respond to light rather the same way as eyes. The more light you hit them with, the bigger the reaction. However, the response is not linear: they're more sensitive to light differences near the middle of their sensitivity range than at the edges. This response can be plotted as a curve. Contrastier films have steeper curves than films with more latitude: Fujichrome Velvia is contrasty, while Kodak Portra is low-contrast. Color films react slightly differently to the component colors that give us full color, which gives them their characteristic color response. For example, Fujichrome Velvia is known for its deep, rich, emerald greens (but pretty funky skin tones), while Fujichrome Provia is known for emphasizing blues in an otherwise pretty neutral rendition.

First Snow. Rollei AF-M 35 on Kodak Portra 400NC.

Photoshop's curves work the same way: it is possible to adjust tonal and color response by modifying tone curves, for example in an adjustment layer. Theoretically, if you know what your starting point is, and the latitude of your starting point is at least equal to the latitude of your desired endpoint, it should be possible to replicate the tone curves of any type of film simply by applying the right curves to an image. It wouldn't even be too difficult to do this; all you'd need to do is shoot a color chart under controlled lighting with your different types of film and your digital camera at its neutral settings, and then use the eyedroppers in the curve tool to nail down the curves so they exactly recreate the color and tonal response of the films. Indeed, this is the approach a few quite high-quality commercial packages appear to have taken: I gave Alien Skin Exposure a try, for example, and it appears to work quite well. It just wasn't exactly what I was looking for.

Chauri herders in Helambu region, Nepal. Vivitar 35-105/3.5 on Kodachrome 64.

The only real trouble with this approach is that it makes some pretty big assumptions -- that your digital originals are always shot at the same settings, and that your film reference shot accurately represents the experience you get from viewing real-life film images. At least in my case, neither holds true: I use and have used a variety of digital cameras with different imaging characteristics, and my experiences of the film images have been affected by a great many things, from the slide projector and screen I used to look at slides, the choices made at the lab (or by myself) to create prints, or, lately, the processing I've done on film scans in the digital darkroom. Most of these are entirely subjective. Therefore, this is more a matter of emotion than science . That's why I set out to create the film curves with little more than a smattering of ideas on how films are supposed to behave -- and a vague idea in my head about what kind of look I was after.

Doug with an ember in his mouth. Canon EF 35/2.0 on EOS-10D, straight conversion from RAW with Raw Shooter Premium and Color Engine. You will see variants of this picture later in the article...

Cross-Process

Gross effects are usually simpler to fake than subtle ones, simply because there's more margin for error. Therefore, my first excursion into simulating film effects with curves was into everybody's favorite 1980's trope, cross-processing E-6 slide film in a C-41 neg process. I also started with it because there was most help to be found on the Net -- complete recipes, even.

Pirate and children. Sigma EX 12-24/4.5-5.6 on EOS-10D. Straight conversion from Raw Shooter Premium, followed by applying "cross-process" curve and a touch of yellow photo filter effect.

Cross-processing basically dramatically increases contrast and makes the colors go all wonky, generally a mix of yellowish and bluish tones. So, what I did was flatten out contrast in the blue channel, cheerfully blow out the red channel, and apply a pretty steep S-curve to the green channel. I tweaked it for a few hours, watching the colors respond to the changes, and got a lot further in getting a feel for how the technique works.

Doug hit with the cross-process curve.

Velviaesque

Next, I tried something else -- a film stock I've never actually liked that much, because for most things both the color and the contrast are too over-the-top for my taste: Velviaesque. Velvia is known for its incredibly rich emerald greens and overall high saturation and contrast. I wanted to recreate this without giving the picture an overall green tint, and keeping skin tones at least marginally believable (even though they never were a forte of Velvia). After a quite a bit of experimentation and some feedback from people on DPReview, I ended up with a pretty steep S-curve in all channels, steepest in the blue and shallowest in the red, with blue leading especially in the shadow range. The apparent strength of the effect depends a lot on your source picture -- if it's a low-contrast, drab-looking picture, the effect is almost subtle, whereas if it starts out colorful or saturated, it's pretty wildly over the top. I find I get quite good control over the effect simply by using it in an adjustment layer and adjusting opacity; if I want even more of it, I duplicate the adjustment layer and adjust opacity on that.

Joanna with cat. Minolta Dimage 7i, with Velviaesque curve applied.

Doug afflicted with a case of Velvia.

Proviaesque

Once I had got Velviaesque down, I went for something more subtle, and therefore more difficult: I tried to recreate the look of my favorite slide film, Fujichrome Provia. I associate the Provia look with a hard-to-describe cool and translucent quality, rich high mid-tones, and rich yet not overcooked blues.

Yet Somebody Loves Me. Canon EF 35/2.0 with EOS-5D. Straight conversion (more or less) from Raw Shooter Premium, with Proviaesque curve applied.

After some experimentation, I ended up with something I quite liked and that appeared to work nicely on a variety of photos I hit it with. It involved a very mild S curve in the red channel, a slightly stronger and slightly pulled-up one in green, and a moderate one with fairly contrasty midtones in the blue channel. The overall effect could be described as "clarifying" -- a slightly cooler, visibly contrastier look with emphasized blues. You probably won't notice anything strange if you see a photo with it applied -- but the difference is actually quite pronounced if you see the original next to it.

Doug enhanced with the Proviaesque curve.

Portraesque

My final attempt was to recreate the look of color negative film. I named this one Portraesque, after my favorite type of film for this sort of thing, Kodak Portra NC400. I wanted a gentler roll-off in the highlights, a bit more contrast in the shadows, and an overall slightly warmer tone: something to make skin tones just a little bit nicer than nature.

Posterestaurant 10. Rollei AF-M 35 on Kodak Portra 400NC.

I ended up with a red channel pulled up just a hair in the highlights, a green channel with a very mild S-curve in it, a blue channel with a mild inverted S-curve, and the RGB curve pulled down a bit in the toe and pulled up in the high midtones. The overall effect is an increase in contrast, a brightening of the high midtones, and a slightly warmer look. It looks best on people pictures.

Doug looking all negative.

Black and white films

To recreate the look and feel of black and white films on digital, you have to consider two separate questions: spectral response and tone curve. Fortunately, wiser heads than mine have pondered the former, and come up with a quite a few simple recipes that do the former. For example, set the R, G, and B channels to the following values with the Monochrome box checked to emulate these films:

Agfa 200X 18,41,41
Agfapan 25 25,39,36
Agfapan 100 21,40,39
Agfapan 400 20,41,39
Ilford Delta 100 21,42,37
Ilford Delta 400 22,42,36
Ilford Delta 400 Pro & 3200 31,36,33
Ilford FP4 28,41,31
Ilford HP5 23,37,40
Ilford Pan F 33,36,31
Ilford SFX 36,31,33
Ilford XP2 Super 21,42,37
Kodak Tmax 100 24,37,39
Kodak Tmax 400 27,36,37
Kodak Tri-X 25,35,40

Carousel. Canon EF 50/1.8 on EOS-5D. I did a quite a lot of work to get to this rendition. Simulating a film may have had some role in the process, but very little really. It's like that with most of my B/W photos.

At this point, I would love to tell you that I've discovered the RGB curve that accurately represents the tonal response of each of these films. I could do that, but I'd be lying. In actual fact, I still use more or less the techniques I describe in my Digital Black and White article to handle tonality -- or, not infrequently, apply the channel mixer on top of one of the above-described color film effects. Printing from black and white always was all about darkroom magic anyway; there really is no single "right" tone curve out there to simulate.

Film grain and its uses

I describe a simple technique for applying film grain in my article on Digital Black and White. All you have to do is apply a layer of scanned film grain onto your image in Overlay mode. I still haven't discovered a better way to simulate film grain in digital processing; however, I have tweaked the technique slightly. The film grain layers I use nowadays have been adjusted to average out at 50% gray, which means they will not affect the tonality of the underlying image. I also use a few different versions for different uses; coarser for a grainy high-ISO look, and superfine for on-screen display only.

See below for samples of the grain fields I use nowadays. Feel free to download and do whatever you like with them.

Pastoral in Black and White. Minolta Dimage 7i, with Tri-X recipe applied in the channel mixer, and hit with a coarse grain field. I thought it made the distance look more interesting.

Adding grain to an image may seem like an affectation more than a serious photo processing tool. It can be that, although it is an affectation that can work quite well with the right kind of picture. However, grain also has some "legitimate" uses -- that is, situations in which adding grain will improve the overall look of the picture whether you actually like a grainy look or not.

The first such situation is using grain as a dither. When you do tone curve manipulations, smooth gradients such as the sky tend to develop posterization -- visible banding in the gradient from light to dark. An effective way to combat posterization is to add noise to the gradient you're manipulating. Grain is just a special kind of noise -- it's just somewhat more attractive than random or Gaussian noise you can add with Photoshop filters. So, if you have a banding problem, you might want to drop in a grain field in Overlay mode, and see if it makes things any better.

Faces. Sony DSC-V3 at ISO800, pushed a stop in post-processing and hit with the Portraesque curve, grain used to mask digital noise.

The second such situation is masking digital noise. Grain may be noise, but it's a nicer kind of noise than the chromatic stuff you get off a digital sensor. Simply overlaying a grain field on a high-ISO digital photo will usually make it look better. If you do the following procedure to reduce chromatic (color) noise on the picture first, the results are even better -- I get quite usable ISO800-1600 photos from my point-and-shoots this way, and have experimentally gone up to ISO12800 with my digital SLR:

  1. Duplicate background layer.
  2. Apply Smart Blur to the top layer, radius 25, threshold 25 (adjust these so that noise gets completely smoothed out, but outlines are preserved, more or less).
  3. Set blend mode to Color on the top layer.

Grain fields, normalized to average out at 50% gray, at four different degrees of coarseness. To make your own, just clone enough of the grain field to cover your photo. I've saved the big grain fields in their own files to save time.

Why Bother?

As I've been messing with these techniques, I've also had to deal with some nagging thoughts about the point of the whole exercise. I find myself liking the results of these experiments a quite a lot, yet it goes against a principle I've sometimes even stated -- that is, that every picture should be considered on its own merits, irrespective of the way it was taken, and processing should respect the integrity of the photographic process. What I've been doing here gets rather close to fakery -- trying to make something (a digital capture) appear to be something it isn't (a film frame). I don't feel entirely comfortable doing this kind of thing, even if does not violate even the very strict ethical rules that apply to journalistic photography.

Long way from the Volga. Canon EF 50/1.8 on EOS-5D. The neg-like look of the Portraesque curve whispers "documentary photography." At least it does that to me.

In the end, our appreciations and perceptions have been formed by the pictures we have seen. Certain types of visual cues have become associated with certain types of pictures. Perhaps there is nothing genuinely nicer about film-like curves or film grain and it's all a matter of what we're used to seeing. Yet these cues, and our reactions to them, remain. These cues are a part of photographic language as well. We may use this language honestly or dishonestly. It all depends on the image.

Saturday Morning. Canon EF 50/1.8 on EOS-5D, straight conversion from RSP, with "Portraesque" curve applied.

Download the curves

If you're interested to try out the curves, here they are.

To use, unzip the archive to wherever you like, apply a Curves adjustment layer to your photo, and use the Load button to load the curve you want from the appropriate file. I strongly encourage you to tweak them to make them your own -- and explore whole new ways of manipulating color and tone with curves. It's much more fun that way.

Update: A reader was kind enough to convert these curves to Gimp Curves format, for use with Gimp and Digikam on Linux. If you've joined the FOSS world and want to take these curves with you, here they are. Thanks, Mario Maggi!

Update: Another reader went through the trouble of converting the black and white adjustments to an Apple Aperture preset. Macheads, find them here. Thank you, Alexander van den Bosch!

Update: Another reader went to the trouble of converting these curves to Lightroom 4 format. They're here. Thanks, Oscar Ciutat!

Nuit d'êté en Provence. Minolta Dimage 7i with the Velviaesque curve.