The skiptake.XXX file provides a skip-take list for 
cropped lev1 images with image configuration id XXX.
The skip-take list is an ASCII file containing exactly
4096 pairs of (skip,take) values defining the cropped 
region of a lev1 image.  The first pair of values is
for the bottom row of the image.

The code below reads a lev1 cropmask on stdin and writes
the skip-take list on stdout.

============= /home/kehcheng/work/hmicomp/makeskiptake.c ==============

#include <stdio.h>

main()
{
    int i,j,skip,take;
    char mask[16777216];

    fread(mask,1,16777216,stdin);
    for (i=0;i<4096;++i) {
	skip = take = 0;
	for (j=0;j<4096;++j) {
	    if (mask[i*4096+j]) break;
	    ++skip;
	}
	for (j=skip;j<4096;++j) {
	    if (!mask[i*4096+j]) break;
	    ++take;
	}
	printf("%d %d\n",skip,take);
    }
}