1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
|
/******************************************************************
Copyright (C) 1996 by Brian Scearce
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
and/or distribute copies of the Software, and to permit persons to whom
the Software is furnished to do so, subject to the following conditions:
1. The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
2. Redistribution for profit requires the express, written permission of
the author.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL BRIAN SCEARCE BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
******************************************************************/
/** Fixdark
Routine to repair dark current artifacts in qcam output.
Basic idea: the Qcam CCD suffers from "dark current";
that is, some of the CCD pixels will leak current under
long exposures, even if they're in the dark, and this
shows up as ugly speckling on images taken in low light.
Fortunately, the leaky pixels are the same from shot to
shot. So, we can figure out which pixels are leaky by
taking some establishing shots in the dark, and try to
fix those pixels on subsequent shots. The dark
establishing shots need only be done once per camera.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "qcam.h"
#define MAX_LOOPS 10
#define FNAME "qcam.darkfile"
static unsigned char master_darkmask1[MAX_HEIGHT][MAX_WIDTH];
static unsigned char master_darkmask2[MAX_HEIGHT / 2 + 1][MAX_WIDTH / 2 + 1];
static unsigned char master_darkmask4[MAX_HEIGHT / 4 + 1][MAX_WIDTH / 4 + 1];
/*
int
read_darkmask()
{
int x, y;
int min_bright;
char darkfile[BUFSIZ], *p;
FILE *fp;
strcpy(darkfile, CONFIG_FILE);
if ( (p = strrchr(darkfile, '/'))) {
strcpy(p+1, FNAME);
} else {
strcpy(darkfile, FNAME);
}
if (!(fp = fopen(darkfile, "r"))) {
#ifdef DEBUG
fprintf(stderr, "Can't open darkfile %s\n", darkfile);
#endif
return 0;
}
if (fread(master_darkmask1, sizeof(unsigned char), MAX_WIDTH*MAX_HEIGHT, fp) !=
MAX_WIDTH*MAX_HEIGHT) {
#ifdef DEBUG
fprintf(stderr, "Error reading darkfile\n");
#endif
return 0;
}
for (y = 0; y < MAX_HEIGHT; y += 2) {
for (x = 0; x < MAX_WIDTH; x += 2) {
min_bright = master_darkmask1[y][x];
if (y < MAX_HEIGHT-1 && master_darkmask1[y+1][x] < min_bright)
min_bright = master_darkmask1[y+1][x];
if (x < MAX_WIDTH-1 && master_darkmask1[y][x+1] < min_bright)
min_bright = master_darkmask1[y][x+1];
if (y < MAX_HEIGHT-1 && x < MAX_WIDTH-1 && master_darkmask1[y+1][x+1] < min_bright)
min_bright = master_darkmask1[y+1][x+1];
master_darkmask2[y/2][x/2] = min_bright;
assert(y/2 < MAX_HEIGHT/2+1);
assert(x/2 < MAX_WIDTH/2+1);
}
}
for (y = 0; y < MAX_HEIGHT/2; y += 2) {
for (x = 0; x < MAX_WIDTH/2; x += 2) {
min_bright = master_darkmask2[y][x];
if (y < MAX_HEIGHT/2-1 && master_darkmask2[y+1][x] < min_bright)
min_bright = master_darkmask2[y+1][x];
if (x < MAX_WIDTH/2-1 && master_darkmask2[y][x+1] < min_bright)
min_bright = master_darkmask2[y][x+1];
if (y < MAX_HEIGHT/2-1 && x < MAX_WIDTH-1 && master_darkmask2[y+1][x+1] < min_bright)
min_bright = master_darkmask2[y+1][x+1];
master_darkmask4[y/2][x/2] = min_bright;
assert(y/2 < MAX_HEIGHT/4+1);
assert(x/2 < MAX_WIDTH/4+1);
}
}
fclose(fp);
return 1;
}
*/
/** fixdark
We first record a list of bad leaky pixels, by making a
number of exposures in the dark. master_darkmask holds
this information. It's a map of the CCD.
master_darkmask[y][x] == val means that the pixel is
unreliable for brightnesses of "val" and above.
We go over the image. If a pixel is bad, look at the
adjacent four pixels, average the ones that have good
values, and use that instead.
*/
int
fixdark (const struct qcam *q, scanbuf * scan)
{
static int init = 0;
static int smallest_dm = 255;
unsigned char darkmask[MAX_HEIGHT][MAX_WIDTH];
unsigned char new_image[MAX_HEIGHT][MAX_WIDTH];
int width, height;
int max_width, max_height;
int x, y;
int ccd_x, ccd_y;
int pixelcount, pixeltotal;
int again, loopcount = 0;
int val;
int brightness = q->brightness;
int scale = q->transfer_scale;
if (!init) {
if (!read_darkmask ())
return 0;
for (y = 0; y < MAX_HEIGHT; y++)
for (x = 0; x < MAX_HEIGHT; x++)
if (master_darkmask1[y][x] < smallest_dm) {
smallest_dm = master_darkmask1[y][x];
#ifdef DEBUG
fprintf (stderr, "Smallest mask is %d at (%d, %d)\n",
smallest_dm, x, y);
#endif
}
init = 1;
}
if (brightness < smallest_dm) {
#ifdef DEBUG
fprintf (stderr,
"Brightness %d (dark current starts at %d), no fixup needed\n",
brightness, smallest_dm);
#endif
return 1;
}
width = q->width / scale;
height = q->height / scale;
max_height = MAX_HEIGHT / scale;
max_width = MAX_WIDTH / scale;
for (y = 0; y < max_height; y++)
for (x = 0; x < max_width; x++)
if (scale == 1) {
darkmask[y][x] = master_darkmask1[y][x];
} else if (scale == 2) {
darkmask[y][x] = master_darkmask2[y][x];
} else if (scale == 4) {
darkmask[y][x] = master_darkmask4[y][x];
} else {
#ifdef DEBUG
fprintf (stderr, "Bad transfer_scale in darkmask assignment!\n");
#endif
return 0;
}
do {
again = 0;
ccd_y = (q->top - 1) / scale;
for (y = 0; y < height; y++, ccd_y++) {
ccd_x = q->left - 1;
ccd_x /= 2;
ccd_x *= 2;
ccd_x /= scale;
for (x = 0; x < width; x++, ccd_x++) {
val = scan[y * width + x];
if (brightness < darkmask[ccd_y][ccd_x]) { /* good pixel */
new_image[y][x] = val;
} else { /* bad pixel */
/* look at nearby pixels, average the good values */
pixelcount = 0;
pixeltotal = 0;
if (x > 0) { /* left */
if (brightness < darkmask[ccd_y][ccd_x - 1]) {
pixelcount++;
pixeltotal += scan[y * width + x - 1];
}
}
if (x < width - 1) { /* right */
if (brightness < darkmask[ccd_y][ccd_x + 1]) {
pixelcount++;
pixeltotal += scan[y * width + x + 1];
}
}
if (y > 0) { /* above */
if (brightness < darkmask[ccd_y - 1][ccd_x]) {
pixelcount++;
pixeltotal += scan[(y - 1) * width + x];
}
}
if (y < height - 1) { /* below */
if (brightness < darkmask[ccd_y + 1][ccd_x]) {
pixelcount++;
pixeltotal += scan[(y + 1) * width + x];
}
}
if (pixelcount == 0) { /* no valid neighbors! */
again = 1;
} else {
new_image[y][x] = pixeltotal / pixelcount;
/* mark this pixel as valid, so we don't loop forever */
darkmask[ccd_y][ccd_x] = 255;
}
}
}
}
for (y = 0; y < height; y++)
for (x = 0; x < width; x++)
scan[y * width + x] = new_image[y][x];
} while (loopcount++ < MAX_LOOPS && again);
#ifdef DEBUG
fprintf (stderr, "Darkmask fix took %d loop%s\n",
loopcount, (loopcount == 1) ? "" : "s");
#endif
return 1;
}
|
