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#ifndef lint
static char SccsId[] = "%W% %G%";
#endif
/* Module: histzero.c (Histogram Zero)
* Subroutine: resolve_zeroes() returns: void
* Copyright: 1989 Smithsonian Astrophysical Observatory
* You may do anything you like with this file except remove
* this copyright. The Smithsonian Astrophysical Observatory
* makes no representations about the suitability of this
* software for any purpose. It is provided "as is" without
* express or implied warranty.
* Modified: {0} Michael VanHilst initial version 30 May 1989
* {n} <who> -- <does what> -- <when>
*/
#include <stdio.h>
#include "hfiles/histeq.h" /* define SubrangeLink */
/*
* Subroutine: resolve_zeroes
* Purpose: Combine groups with zero alloted levels with adjoining groups
* Note: Adjoining groups are large count single level groups
* Called by: histrogram_equalize() above
*/
void resolve_zeroes ( PriorLink, zeroes )
SubrangeLink *PriorLink;
int zeroes;
{
SubrangeLink *ThisLink, *NextLink;
int a_count, b_count, z1count, z2count;
static void merge_links();
/* if very first entry is a zero allocated link */
if( PriorLink->color_levels == 0 ) {
/* merge this and next */
merge_links(PriorLink);
zeroes--;
}
/* scan for the zero allocated links */
while( zeroes > 0 ) {
ThisLink = PriorLink->next;
#ifdef DEBUG
/* if reached the end of the list, we had an error */
if( ThisLink == 0 ) {
(void)fprintf(stderr,"Zero error\n");
return;
}
#endif
/* if we are about to hit a zero */
if( ThisLink->color_levels == 0 ) {
/* if it is the last zero merge with prior */
NextLink = ThisLink->next;
if( NextLink == 0 ) {
merge_links(PriorLink);
return;
}
a_count = PriorLink->pixel_area;
b_count = NextLink->pixel_area;
/* if the preceding link is smaller than the trailing link */
if( a_count > b_count ) {
merge_links(PriorLink);
zeroes--;
} else {
/* probe beyond */
if( NextLink->next != 0 ) {
if( NextLink->next->color_levels != 0 ) {
/* if new competition, merge with next link */
merge_links(ThisLink);
zeroes--;
} else {
z1count = ThisLink->pixel_area;
z2count = NextLink->next->pixel_area;
/* where would the next one go? */
if( (NextLink->next->next == 0) ||
(NextLink->next->next->pixel_area > (b_count + z2count)) ) {
if( (b_count + z2count) > (a_count + z1count) ) {
merge_links(PriorLink);
} else {
merge_links(ThisLink);
}
} else
merge_links(ThisLink);
zeroes--;
}
} else {
merge_links(PriorLink);
zeroes--;
}
}
}
PriorLink = ThisLink;
}
}
/*
* Subroutine: merge_links
* Purpose: Combine two links of histogram group list
*/
static void merge_links ( subrange )
SubrangeLink *subrange;
{
SubrangeLink *lostlink;
lostlink = subrange->next;
subrange->next = lostlink->next;
subrange->max_entry = MAX(subrange->max_entry, lostlink->max_entry);
subrange->pixel_area += lostlink->pixel_area;
subrange->high = lostlink->high;
subrange->range += lostlink->range;
subrange->nz_entries += lostlink->nz_entries;
subrange->excess_pixels += lostlink->excess_pixels;
subrange->color_levels += lostlink->color_levels;
free( (char *)lostlink );
}
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