The Red Planet, And My Fight Against Color Banding
This week’s Photoblog entry, entitled “Red Planet”, didn’t seem like it would require much post processing, but boy was I in for a little surprise…
(Brightness boosted for illustration)
As you can tell, this photo is mostly one color, red. I didn’t think much of it at first, but when I tried to remove the sensor noise from the photo, I started to see some nasty color banding. There are only 256 different shades for each color channel (Red, Green and Blue), and in a photo which primarily occupies only one of those channels, the colors are rather limited.
As a result from the noise filter, the shades of red had noticeable banding, resembling a posterization effect. I knew I had to smooth out the shades, but how?
My first attempt was to apply a slight blur to the photo, which didn’t work. My second attempt was to add a small amount of noise to the photo, to help blend the colors, but this didn’t seem to work either. So I turned to Google, to see how others had solved this problem.
After some searching, I came across the perfect solution, which just so happens to use the noise filter. It wasn’t far from what I had tried earlier, but there was one important difference. Rather than adding noise to the entire image, you need to separate each of the color channels, and apply the noise filter to each one, individually. After I applied the slight, (0.2) noise to each of the channels, the colors blended beautifully, and the color banding was gone!
That’s one trick I’m definitely not going to forget!
