Up: Image Analysis Tasks
Computes the background image of an input image using a thresholding and
a smoothing algorithm based on the conjugate gradient method. The back-
ground image is computed as follows
- First the image is thresholded between THRESHOLD$ and THRESH-
OLD$. All pixels outside this range are blanked.
- Then the image is smoothed using the conjugate gradient method, with
NITER$ iterations and a smoothing parameter P$. Blanked pixels are
thus interpolated in the process.
The output image is the background image. P$ should be large enough to
yield some smoothing (1 to 100, try...), and NITER$ also to assure con-
vergence especially in "blanked" areas (NITER$ = 20 is typical).