Using Photoshop Curves To Simulate Film Effects

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.

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.

Retouching Techniques Using Photoshop

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.

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.

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.

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