DxO FilmPack 3 and high sensitivity:
replacing digital noise with silver halide grain
This tutorial shows you how digital noise present in images taken at high ISO can be advantageously corrected and replaced by a silver halide grainsimulation, thanks to DxO FilmPack. This treatment can give body and texture to the processed photo, while eliminating artifacts, irregular clusters of pixels, and unsightly noise luminance and chrominance. In the example that follows, we will treat a color photo, but you can follow the same steps using a black & white image.
1
Choose an image with pronounced digital noise and open it in DxO FilmPack. In the top toolbar, select the side-by-side preview, then enlarge the image to at least 1:1 (100%) in order to work on it with the greatest possible accuracy.
2
In this step, we start by correcting the noise. We can visually distinguish two types of noise: chrominance noise, which manifests itself as random spots or patches of color, and luminancenoise, which manifests itself as darker or lighter spots or patches that give images a grainy appearance.In the Controls pane, open the Noise Removal palette. (If the Controls pane on the right side of the screen is not already open, click on Show Controlsin the upper right corner of the FilmPack window.)
Move the Luminance slider to the right until the grain in the image disappears, making the image seem a bit excessively smooth, but be careful not to delete any details such as (in our example) the facial features. If the dark zones and background turn into piles of colored pixels (colored noise), move the Chrominance slider to the right enough to eliminate them as much as possible.
3
Now we will replace the digital noise that we suppressed by applying a more uniform and aesthetically-pleasing silver halide film grain found in DxO FilmPack.
In the Film section of the Film Grain palette, select a 400 or 800 ISO film type with a noticeable grain, such as Fuji Superia X-Tra™ 800 for color, or Kodak Tri-X™ 400 for black & white. DxO FilmPack offers you dozens of black & white and color film looks (positive, negative, cross-treatment).
4
In this step, we adjust the intensity of the silver halide film grain that we have applied to our image.
After choosing the film type, you can control the intensity and size of the grain in the Film Grain palette. Moving the Intensity slider to the right accentuates the grain. The goal is to add enough film grain without giving the impression of having added artifacts that look like noise. Depending on the film type you chose, the effect will be more or less subtle.
5
Now we need to adjust the grain size of the silver halide film that we have applied to our image with respect to the film format used. The grain visible on a print will in fact depend on the ratio of the enlargement to the original media. For an equivalent size print, a 24x36mm standard-format silver halide film image will show a lot more grain than a 6x6cm silver halide film image (such as one obtains from medium-format cameras).The Size palette allows you to specify the format of the original, and if you select Custom format, you will be able to manually select the Grain size using the appropriate slider. The setting possibilities are numerous, which means that with a bit of experience, you will be able to use these settings with even greater finesse.
Of course, if you want to print this photo, we advise you to make a few test proofs so as to judge the quality and relevance of the settings you choose.
You can see in our example that the digital noise has been completely eliminated and advantageously replaced by the simulated film grain, which acts at the structural level of the image, rather than as just a simple superimposed masking effect.
For better understanding
This comparison clearly demonstrates the importance of suppressing the digital noise before applying the grain: at left, we have the original image; in the center, the image to which grain has been added without first correcting the noise, which can generate a mass of rather unattractive pixels; and finally, at right, the addition of grain after having corrected the noise.
Black & white variation
This method works perfectly with black and white images. By following steps 3 – 5 and applying the corresponding settings, you will obtain images that benefit from enhanced body and texture. We suggest that you continue by trying this with the Kodak Tri-X™ 400 film simulation.
This tutorial was produced DxO FilmPack 3 in plugin mode with a host application (i.e., Lightroom, Photoshop, or Aperture).
You can also use FilmPack as a standalone application or to make the same corrections directly in DxO Optics Pro (tab: Customize; palette: Detail; section: DxO FilmPack Grain).
DxO FilmPack
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For users of DxO Optics Pro
Take advantage of the automatic noise reduction feature thanks to the calibration of your camera both for RAW and JPEG. To learn more about the complementary features of DxO FilmPack, you can try out the trial version by launching it directly from the DxO Optics Pro menus.
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