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253 lines
7.3 KiB
C
253 lines
7.3 KiB
C
/******************************************************************
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Copyright (C) 1996 by Brian Scearce
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this software and associated documentation files (the
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"Software"), to deal in the Software without restriction, including
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without limitation the rights to use, copy, modify, merge, publish,
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and/or distribute copies of the Software, and to permit persons to whom
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the Software is furnished to do so, subject to the following conditions:
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1. The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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2. Redistribution for profit requires the express, written permission of
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the author.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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IN NO EVENT SHALL BRIAN SCEARCE BE LIABLE FOR ANY CLAIM, DAMAGES OR
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OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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OTHER DEALINGS IN THE SOFTWARE.
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******************************************************************/
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/** Fixdark
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Routine to repair dark current artifacts in qcam output.
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Basic idea: the Qcam CCD suffers from "dark current";
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that is, some of the CCD pixels will leak current under
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long exposures, even if they're in the dark, and this
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shows up as ugly speckling on images taken in low light.
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Fortunately, the leaky pixels are the same from shot to
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shot. So, we can figure out which pixels are leaky by
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taking some establishing shots in the dark, and try to
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fix those pixels on subsequent shots. The dark
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establishing shots need only be done once per camera.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <assert.h>
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#include "qcam.h"
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#define MAX_LOOPS 10
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#define FNAME "qcam.darkfile"
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static unsigned char master_darkmask1[MAX_HEIGHT][MAX_WIDTH];
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static unsigned char master_darkmask2[MAX_HEIGHT/2+1][MAX_WIDTH/2+1];
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static unsigned char master_darkmask4[MAX_HEIGHT/4+1][MAX_WIDTH/4+1];
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/*
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int
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read_darkmask()
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{
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int x, y;
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int min_bright;
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char darkfile[BUFSIZ], *p;
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FILE *fp;
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strcpy(darkfile, CONFIG_FILE);
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if ( (p = strrchr(darkfile, '/'))) {
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strcpy(p+1, FNAME);
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} else {
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strcpy(darkfile, FNAME);
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}
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if (!(fp = fopen(darkfile, "r"))) {
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#ifdef DEBUG
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fprintf(stderr, "Can't open darkfile %s\n", darkfile);
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#endif
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return 0;
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}
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if (fread(master_darkmask1, sizeof(unsigned char), MAX_WIDTH*MAX_HEIGHT, fp) !=
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MAX_WIDTH*MAX_HEIGHT) {
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#ifdef DEBUG
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fprintf(stderr, "Error reading darkfile\n");
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#endif
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return 0;
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}
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for (y = 0; y < MAX_HEIGHT; y += 2) {
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for (x = 0; x < MAX_WIDTH; x += 2) {
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min_bright = master_darkmask1[y][x];
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if (y < MAX_HEIGHT-1 && master_darkmask1[y+1][x] < min_bright)
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min_bright = master_darkmask1[y+1][x];
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if (x < MAX_WIDTH-1 && master_darkmask1[y][x+1] < min_bright)
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min_bright = master_darkmask1[y][x+1];
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if (y < MAX_HEIGHT-1 && x < MAX_WIDTH-1 && master_darkmask1[y+1][x+1] < min_bright)
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min_bright = master_darkmask1[y+1][x+1];
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master_darkmask2[y/2][x/2] = min_bright;
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assert(y/2 < MAX_HEIGHT/2+1);
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assert(x/2 < MAX_WIDTH/2+1);
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}
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}
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for (y = 0; y < MAX_HEIGHT/2; y += 2) {
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for (x = 0; x < MAX_WIDTH/2; x += 2) {
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min_bright = master_darkmask2[y][x];
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if (y < MAX_HEIGHT/2-1 && master_darkmask2[y+1][x] < min_bright)
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min_bright = master_darkmask2[y+1][x];
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if (x < MAX_WIDTH/2-1 && master_darkmask2[y][x+1] < min_bright)
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min_bright = master_darkmask2[y][x+1];
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if (y < MAX_HEIGHT/2-1 && x < MAX_WIDTH-1 && master_darkmask2[y+1][x+1] < min_bright)
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min_bright = master_darkmask2[y+1][x+1];
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master_darkmask4[y/2][x/2] = min_bright;
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assert(y/2 < MAX_HEIGHT/4+1);
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assert(x/2 < MAX_WIDTH/4+1);
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}
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}
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fclose(fp);
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return 1;
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}
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*/
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/** fixdark
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We first record a list of bad leaky pixels, by making a
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number of exposures in the dark. master_darkmask holds
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this information. It's a map of the CCD.
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master_darkmask[y][x] == val means that the pixel is
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unreliable for brightnesses of "val" and above.
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We go over the image. If a pixel is bad, look at the
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adjacent four pixels, average the ones that have good
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values, and use that instead.
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*/
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int
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fixdark(const struct qcam *q, scanbuf *scan)
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{
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static int init = 0;
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static int smallest_dm = 255;
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unsigned char darkmask[MAX_HEIGHT][MAX_WIDTH];
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unsigned char new_image[MAX_HEIGHT][MAX_WIDTH];
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int width, height;
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int max_width, max_height;
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int x, y;
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int ccd_x, ccd_y;
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int pixelcount, pixeltotal;
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int again, loopcount = 0;
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int val;
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int brightness = q->brightness;
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int scale = q->transfer_scale;
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if (!init) {
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if (!read_darkmask()) return 0;
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for (y = 0; y < MAX_HEIGHT; y++)
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for (x = 0; x < MAX_HEIGHT; x++)
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if (master_darkmask1[y][x] < smallest_dm) {
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smallest_dm = master_darkmask1[y][x];
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#ifdef DEBUG
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fprintf(stderr, "Smallest mask is %d at (%d, %d)\n",
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smallest_dm, x, y);
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#endif
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}
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init = 1;
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}
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if (brightness < smallest_dm) {
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#ifdef DEBUG
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fprintf(stderr, "Brightness %d (dark current starts at %d), no fixup needed\n",
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brightness, smallest_dm);
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#endif
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return 1;
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}
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width = q->width / scale;
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height = q->height / scale;
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max_height = MAX_HEIGHT / scale;
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max_width = MAX_WIDTH / scale;
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for (y = 0; y < max_height; y++)
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for (x = 0; x < max_width; x++)
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if (scale == 1) {
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darkmask[y][x] = master_darkmask1[y][x];
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} else if (scale == 2) {
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darkmask[y][x] = master_darkmask2[y][x];
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} else if (scale == 4) {
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darkmask[y][x] = master_darkmask4[y][x];
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} else {
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#ifdef DEBUG
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fprintf(stderr, "Bad transfer_scale in darkmask assignment!\n");
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#endif
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return 0;
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}
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do {
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again = 0;
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ccd_y = (q->top-1)/scale;
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for (y = 0; y < height; y++, ccd_y++) {
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ccd_x = q->left-1;
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ccd_x /= 2;
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ccd_x *= 2;
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ccd_x /= scale;
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for (x = 0; x < width; x++, ccd_x++) {
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val = scan[y*width + x];
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if (brightness < darkmask[ccd_y][ccd_x]) { /* good pixel */
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new_image[y][x] = val;
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} else { /* bad pixel */
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/* look at nearby pixels, average the good values */
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pixelcount = 0;
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pixeltotal = 0;
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if (x > 0) { /* left */
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if (brightness < darkmask[ccd_y][ccd_x-1]) {
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pixelcount++;
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pixeltotal += scan[y*width + x - 1];
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}
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}
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if (x < width-1) { /* right */
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if (brightness < darkmask[ccd_y][ccd_x+1]) {
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pixelcount++;
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pixeltotal += scan[y*width + x + 1];
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}
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}
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if (y > 0) { /* above */
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if (brightness < darkmask[ccd_y-1][ccd_x]) {
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pixelcount++;
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pixeltotal += scan[(y-1)*width + x];
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}
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}
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if (y < height-1) { /* below */
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if (brightness < darkmask[ccd_y+1][ccd_x]) {
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pixelcount++;
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pixeltotal += scan[(y+1)*width + x];
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}
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}
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if (pixelcount == 0) { /* no valid neighbors! */
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again = 1;
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} else {
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new_image[y][x] = pixeltotal / pixelcount;
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/* mark this pixel as valid, so we don't loop forever */
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darkmask[ccd_y][ccd_x] = 255;
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}
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}
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}
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}
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for (y = 0; y < height; y++)
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for (x = 0; x < width; x++)
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scan[y*width + x] = new_image[y][x];
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} while (loopcount++ < MAX_LOOPS && again);
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#ifdef DEBUG
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fprintf(stderr, "Darkmask fix took %d loop%s\n",
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loopcount, (loopcount == 1)?"":"s");
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#endif
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return 1;
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}
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