A supercharger is a device that mechanically forces more fuel and air into an engine. We’re going to do the same thing with our pictures and noise reduction application. In this article we’re going to use Photoshop by Adobe and Noiseless CK by Macphun.
Now let’s see why noise occurs. Light travels as a wave and as it enters the camera it stimulates the CMOS receptors on the sensor. Each pixel averages the information it receives in red, green and blue wavelengths. If the pixel captures enough information, it will reproduce an accurate representation of the real world. If the sensitivity is too high or if the shutter speed is too fast, then an insufficient amount of information is captured by the pixel to form an accurate image. The sensor does not have enough time to make a proper average of the information.
The human eye does the same thing, it averages the amount of information it receives to form a picture. When we look at a photograph with noise from a distance, the eye averages the information in the picture looks reasonably good. When we zoom in on the pixels, that’s when we see all the red green and blue dots. Let’s look at the picture below:
When it’s small or when we look at it from a distance, it looks pretty good. But, let’s zoom in:
See the red green and blue pixels? There is also a loss of detail.
Now let’s turn on our supercharger. The trick, is to take several shots of the same image. Ideally, we do this with a tripod. Due to the random nature of noise, each picture will have a unique pattern of noise.
I took the above picture six times. Now, let’s process it.
We start with Photoshop. Go to the File menu, select Scripts, then “Load Files into Stack…”.
Select all of your source files, and tick off the options “Attempt to Automatically Align Source Images” and “Create Smart Object after Loading Layers”.
Then in Photoshop, select Layer->Smart Objects->Stack Mode, and Mean.
And voilà! You’ve done most of the supercharging work! You should see the noise greatly reduce. The last step is to call up Noiseless CK from Photoshop.
Look at the results! All that was needed was “Light” noise reduction.
The results are fantastic!
If I run the original file through Noiseless CK without supercharging it, I need to apply “Strong” noise reduction. The resulting file is not as nice as the one we produced with supercharging and the result has artifacts that we won’t find using supercharging.
The supercharged image is on the left and the image that was run directly through Noiseless CK with “Strong” noise reduction is on the right.
Try it. I think you’ll find the results amazing.