Exploiting High ISO Noise

Both film grain and digital noise are normally avoided if possible and minimized if not. However, there is a long tradition of actually emphasizing film grain, particulary from high ISO B&W film stocks. We've all seen the look. Noise is the digital equivalent of grain, but unlike B&W film grain, noise comes in colours:

Fig. 1: Chromatic noise (1600 ISO)

Will future generations come to savour this effect as previous generations did B&W film grain? Got me; but for now we have an interesting option.

This pic is just a grab shot I took out a 15th floor window (as always, click on any thick-bordered image for a larger version):

Fig. 2: Full frame

I shot it using a Lumix LX1 at 400 ISO but with -2 stops exposure comp. to simulate 1600 ISO. I wanted to see how much grain there would be, given that nearly every one considers even the LX1's 400 ISO to be unusable. You can see from Fig. 1 what the resulting noise is like. However, for the following two crops I left the luminance noise alone while maximally removing the chroma noise. (This is an option available in Raw Shooter, which is what I used, as well as Noise Ninja, Neat Image, and many other apps.) I also applied a small amount of USM:

Fig. 3: Non-chromatic noise (100% crop)

Fig. 4: Non-chromatic noise (100% crop)

Now we have something that, when printed, begins to resemble moderately grainy B&W film. And just as with B&W we can vary the "development" in a multitude of ways. Here, for example, I've applied Photoshop's high pass filter to Fig. 3 and set the blend mode to color burn:

Fig. 5: High pass filter

If we try to duplicate the B&W grainy look, we'll never satisfy the purists (note the bacillus colony texture due in part to exaggerated JPEG artifacting, just for example). But nothing is stopping us from exploring new territory, however grotesque and deranged ;) photo-conservatives may find the results to be...

Fig. 6: Added saturation, hue shift, sharpening, kitchen sink

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