Simulating Film Effects with Curves - Petteri's Pontifications

Simulating Film Effects with CurvesI know I'm not exactly inventing the wheel here, but I have been treading one moderately well-troddenpath recently: attempting to recreate the look of a few types of film I know and like. The method I chosewas the simplest possible: attempting to create a set of Photoshop curves I could use to give photos theselooks with a minimum of fuss. I don't even pretend to aim for accuracy. It wouldn't really help much inany 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-sidecomparison shots of film versus digital, although I have compared my results against some scans I'vemade previously -- and nope, they're not exact matches, nor, I think, will they ever be. But they do go atleast 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, thishas 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 dayswas choosing what kind of film to shoot. Slow, saturated, contrasty slide film gives a completely differentfeel to a picture than fast, grainy, high-latitude color negative film. Different brands and makes of slidegive 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 cartoonishway. When the choice was well made, the result just looked so wonderfully right that it would almost

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make a grown man weep... and when the choice was wrong, it could mean not getting the picture at all, orjumping through any number of hoops to getting something remotely acceptable out of the exposedframe.

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 prettymuch stuck with whatever happens to sit inside our cameras, and our choice of camera is to a great degreedictated 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 portraitcameras, landscape cameras, sports cameras, nighttime cameras, architecture cameras, black-and-whitecameras, street cameras, photojournalism cameras, like they used to have dedicated films for each of thesemissions, and more. Instead, the creative choice of film stock has moved to the digital darkroom. Digitalcapture can give us a starting point that's more or less neutral and lends itself to being massaged into anyof the looks and feels associated with these types of photography. The only trouble is getting there,especially in a repeatable or consistent way.

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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 thereaction. However, the response is not linear: they're more sensitive to light differences near the middle oftheir sensitivity range than at the edges. This response can be plotted as a curve. Contrastier films havesteeper curves than films with more latitude: Fujichrome Velvia is contrasty, while Kodak Portra islow-contrast. Color films react slightly differently to the component colors that give us full color, whichgives 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 inan otherwise pretty neutral rendition.

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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 tonecurves, for example in an adjustment layer. Theoretically, if you know what your starting point is, and thelatitude of your starting point is at least equal to the latitude of your desired endpoint, it should bepossible to replicate the tone curves of any type of film simply by applying the right curves to an image. Itwouldn't even be too difficult to do this; all you'd need to do is shoot a color chart under controlledlighting with your different types of film and your digital camera at its neutral settings, and then use theeyedroppers in the curve tool to nail down the curves so they exactly recreate the color and tonal responseof the films. Indeed, this is the approach a few quite high-quality commercial packages appear to havetaken: I gave Alien Skin Exposure [http://www.alienskin.com/exposure/index.html] 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 digitaloriginals are always shot at the same settings, and that your film reference shot accurately represents theexperience you get from viewing real-life film images. At least in my case, neither holds true: I use andhave used a variety of digital cameras with different imaging characteristics, and my experiences of thefilm images have been affected by a great many things, from the slide projector and screen I used to lookat slides, the choices made at the lab (or by myself) to create prints, or, lately, the processing I've done onfilm scans in the digital darkroom. Most of these are entirely subjective. Therefore, this is more a matterof emotion than science . That's why I set out to create the film curves with little more than a smatteringof ideas on how films are supposed to behave -- and a vague idea in my head about what kind of look Iwas after.

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Doug with an ember in his mouth. Canon EF 35/2.0 on EOS-10D, straight conversion from RAW withRaw 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'strope, cross-processing E-6 slide film in a C-41 neg process. I also started with it because there was mosthelp 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 ShooterPremium, followed by applying "cross-process" curve and a touch of yellow photo filter effect.

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Cross-processing basically dramatically increases contrast and makes the colors go all wonky, generally amix of yellowish and bluish tones. So, what I did was flatten out contrast in the blue channel, cheerfullyblow out the red channel, and apply a pretty steep S-curve to the green channel. I tweaked it for a fewhours, watching the colors respond to the changes, and got a lot further in getting a feel for how thetechnique 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 thingsboth the color and the contrast are too over-the-top for my taste: Velviaesque. Velvia is known for itsincredibly rich emerald greens and overall high saturation and contrast. I wanted to recreate this withoutgiving the picture an overall green tint, and keeping skin tones at least marginally believable (even thoughthey never were a forte of Velvia). After a quite a bit of experimentation and some feedback from peopleon DPReview, I ended up with a pretty steep S-curve in all channels, steepest in the blue and shallowestin the red, with blue leading especially in the shadow range. The apparent strength of the effect depends alot on your source picture -- if it's a low-contrast, drab-looking picture, the effect is almost subtle, whereasif it starts out colorful or saturated, it's pretty wildly over the top. I find I get quite good control over theeffect simply by using it in an adjustment layer and adjusting opacity; if I want even more of it, Iduplicate the adjustment layer and adjust opacity on that.

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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 triedto recreate the look of my favorite slide film, Fujichrome Provia. I associate the Provia look with ahard-to-describe cool and translucent quality, rich high mid-tones, and rich yet not overcooked blues.

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

After some experimentation, I ended up with something I quite liked and that appeared to work nicely ona variety of photos I hit it with. It involved a very mild S curve in the red channel, a slightly stronger andslightly 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 withemphasized blues. You probably won't notice anything strange if you see a photo with it applied -- but thedifference is actually quite pronounced if you see the original next to it.

Doug enhanced with the Proviaesque curve.

Portraesque

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My final attempt was to recreate the look of color negative film. I named this one Portraesque, after myfavorite type of film for this sort of thing, Kodak Portra NC400. I wanted a gentler roll-off in thehighlights, a bit more contrast in the shadows, and an overall slightly warmer tone: something to makeskin 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 mildS-curve in it, a blue channel with a mild inverted S-curve, and the RGB curve pulled down a bit in the toeand pulled up in the high midtones. The overall effect is an increase in contrast, a brightening of the highmidtones, and a slightly warmer look. It looks best on people pictures.

Doug looking all negative.

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Black and white films

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

Agfa 200X 18,41,41Agfapan 25 25,39,36Agfapan 100 21,40,39Agfapan 400 20,41,39Ilford Delta 100 21,42,37Ilford Delta 400 22,42,36Ilford Delta 400 Pro & 3200 31,36,33Ilford FP4 28,41,31Ilford HP5 23,37,40Ilford Pan F 33,36,31Ilford SFX 36,31,33Ilford XP2 Super 21,42,37Kodak Tmax 100 24,37,39Kodak Tmax 400 27,36,37Kodak 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 afilm may have had some role in the process, but very little really. It's like that with most of my B/Wphotos.

At this point, I would love to tell you that I've discovered the RGB curve that accurately represents thetonal response of each of these films. I could do that, but I'd be lying. In actual fact, I still use more or lessthe techniques I describe in my Digital Black and White[/pont/How_to/n_Digital_BW/a_Digital_Black_and_White.html] article to handle tonality -- or, notinfrequently, apply the channel mixer on top of one of the above-described color film effects. Printingfrom black and white always was all about darkroom magic anyway; there really is no single "right" tonecurve 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.

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/pont/How_to/n_Digital_BW/a_Digital_Black_and_White.html] All you have to do is apply a layer ofscanned film grain onto your image in Overlay mode. I still haven't discovered a better way to simulatefilm grain in digital processing; however, I have tweaked the technique slightly. The film grain layers Iuse nowadays have been adjusted to average out at 50% gray, which means they will not affect thetonality of the underlying image. I also use a few different versions for different uses; coarser for a grainyhigh-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 withthem.

Pastoral in Black and White. Minolta Dimage 7i, with Tri-X recipe applied in the channel mixer, and hitwith 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 canbe that, although it is an affectation that can work quite well with the right kind of picture. However, grainalso has some "legitimate" uses -- that is, situations in which adding grain will improve the overall look ofthe 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, smoothgradients such as the sky tend to develop posterization -- visible banding in the gradient from light todark. An effective way to combat posterization is to add noise to the gradient you're manipulating. Grainis just a special kind of noise -- it's just somewhat more attractive than random or Gaussian noise you canadd with Photoshop filters. So, if you have a banding problem, you might want to drop in a grain field inOverlay mode, and see if it makes things any better.

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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 thanthe chromatic stuff you get off a digital sensor. Simply overlaying a grain field on a high-ISO digitalphoto will usually make it look better. If you do the following procedure to reduce chromatic (color) noiseon the picture first, the results are even better -- I get quite usable ISO800-1600 photos from mypoint-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 completelysmoothed out, but outlines are preserved, more or less).

3. Set blend mode to Color on the top layer.

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

Why Bother?

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

Long way from the Volga. Canon EF 50/1.8 on EOS-5D. The neg-like look of the Portraesque curvewhispers "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. Certaintypes of visual cues have become associated with certain types of pictures. Perhaps there is nothinggenuinely nicer about film-like curves or film grain and it's all a matter of what we're used to seeing. Yetthese cues, and our reactions to them, remain. These cues are a part of photographic language as well. Wemay 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.

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Download the curves

If you're interested to try out the curves, here they are [filmcurves.zip].

To use, unzip the archive to wherever you like, apply a Curves adjustment layer to your photo, and usethe Load button to load the curve you want from the appropriate file. I strongly encourage you to tweakthem 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 Gimpand Digikam on Linux. If you've joined the FOSS world and want to take these curves with you, here theyare. [gimp_and_digikam.zip] Thanks, Mario Maggi![http://www.pentaxiani.it/cpg1416/index.php?cat=10250]

Update: Another reader went through the trouble of converting the black and white adjustments to anApple Aperture preset. Macheads, find them here. [PP_BW.zip] Thank you, Alexander van den Bosch![http://www.flickr.com/photos/atvandenbosch/]

Update: Another reader went to the trouble of converting these curves to Lightroom 4 format. They'rehere. [LR4_curves.zip] Thanks, Oscar Ciutat! [http://www.oscarciutat.com/]

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

Unless otherwise indicated, all materials on this site are by Petteri Sulonen. They are licensed under the Creative CommonsAttribution License [http://creativecommons.org/licenses/by/1.0/fi/]. I would appreciate it if you dropped me a line if you want toreproduce them. Any trademarks are property of their respective owners; their use is purely editorial and does not constitute aninfringement.

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