TIFF and LibTiff Mail List Archive

1998.05.27 14:30 "Best Algorithm For Reducing An Image to 1/4 Of Its Size????", by Frank Kim


I'm looking for the best algorithm for reducing a TIFF image to 1/4 of its size. For example, I want to take a 1000x1000 image and make it into a 250x250 image.

Taking out 1 out of every 4 pixels usually gets an output that is quite bad looking. So I tried my own algorithm which produces better results but is still not great. Here is the algorithm:

  1. Start going through the image row by row, skipping every other row.
  2. In each row, start going through each pixel, skipping every other pixel.
  3. For each pixel, apply a simple pyramid filter (weight of 1/4 in the middle, 1/8 for the adjacent pixels, 1/16 for the diagonal pixels) upon the area centered around the current pixel, to get the value of the new pixel for the new image.

Does anyone have a better algorithm? I'm sure there must be better ones.


Frank Kim