Tuesday, November 21, 2017

decrease noise level in pictures with enfuse and align_image_stack

    Reducing the noise by stacking 2 or 3 or 4 or more pictures is based on the fact that, in every picture you take, the noise is randomly distributed.
    This technique is usefull especially for still subjects and can be used mainly for real estate photography, product photography and sometimes for landscape photography.
    I usually  have 3 pictures for this. You can increase the efficiency of noise reduction by using 4 or 5 pictures. Beyond that it's very hard to align the pictures and, additionally, the efficiency is about the same as using a maximum of 4 or 5 pictures.
   The pictures are aligned with align_image_stack:


align_image_stack -C -g 9 -f 35 -a aligned_ *.jpg


     This command will align every picture whose name is ending in ".jpg", in working folder . Aligned pictures will have "aligned_" prefix for their name and will be saved as tif pictures.
    Then we will blend these aligned images into one single picture with enfuse:


enfuse -o output_name.tif --exposure-weight=1 --entropy-weight=0 --saturation-weight=0 aligned_*.tif


    The resulting picture will be saved as "output_name.tif".

    Results are very satisfying and good!