Removing iso noise in gimp

To be fair, I cheated a little bit… The relatively noise-free image you see above shot at ISO 25, is actually combined from 10 identical shots. The trick is that I combined all of the shots using a median evaluation in Imagemagick. This basically means that for every pixel in the image, there were 10 pixel values to choose from.

Imagemagick automatically picked the pixel value that was closest to the middle. If there were an even number of values, the median is calculated as the average of the two numbers in the middle usually.

This is different from the averaging I had done previously, where the pixel value was an average of all the values at a given pixel location though both methods could be used to reduce noise in the final result. Pretty neat, right? Add a comment. Active Oldest Votes. Sign up or log in Sign up using Google.

Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast Making Agile work for data science. Stack Gives Back Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Related Hot Network Questions. You could think of it like the opposite of unsharpen mask that sharpens everything with contrast above a certain threshold.

Normally I find that both settings should be between 5 and 10, where low numbers has less effect and higher numbers more, but this is very depending on the camera.

In short, maximum delta should be just high enough for the filter to kick in on the noise and blur radius should be just high enough to remove it actually blend it with neighboring areas. After playing with the settings a bit I liked the clean look of a blur radius of 10 and maximum delta of