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
|
/*********************************************************************/
/* ppmspread - randomly displace a PPM's pixels by a certain amount */
/* Frank Neumann, October 1993 */
/* V1.1 16.11.1993 */
/* */
/* version history: */
/* V1.0 12.10.1993 first version */
/* V1.1 16.11.1993 Rewritten to be NetPBM.programming conforming */
/*********************************************************************/
#include <string.h>
#include "ppm.h"
int
main(int argc,
char * argv[]) {
FILE * ifP;
int argn, rows, cols;
unsigned int row;
pixel ** destarray, ** srcarray;
pixel * pP;
pixel * pP2;
pixval maxval;
pixval r1, g1, b1;
int amount;
const char * const usage = "amount [ppmfile]\n amount: # of pixels to displace a pixel by at most\n";
/* parse in 'default' parameters */
ppm_init(&argc, argv);
argn = 1;
/* parse in amount & seed */
if (argn == argc)
pm_usage(usage);
if (sscanf(argv[argn], "%d", &amount) != 1)
pm_usage(usage);
if (amount < 0)
pm_error("amount should be a positive number");
++argn;
/* parse in filename (if present, stdin otherwise) */
if (argn != argc)
{
ifP = pm_openr(argv[argn]);
++argn;
}
else
ifP = stdin;
if (argn != argc)
pm_usage(usage);
srcarray = ppm_readppm(ifP, &cols, &rows, &maxval);
destarray = ppm_allocarray(cols, rows);
/* clear out the buffer */
for (row = 0; row < rows; ++row)
memset(destarray[row], 0, cols * sizeof(pixel));
srand(pm_randseed());
/* start displacing pixels */
for (row = 0; row < rows; ++row) {
unsigned int col;
pP = &srcarray[row][0];
for (col = 0; col < cols; ++col) {
int const xdis = (rand() % (amount+1)) - ((amount+1) / 2);
int const ydis = (rand() % (amount+1)) - ((amount+1) / 2);
int const xnew = col + xdis;
int const ynew = row + ydis;
/* only set the displaced pixel if it's within the bounds
of the image
*/
if (xnew >= 0 && xnew < cols && ynew >= 0 && ynew < rows) {
/* displacing a pixel is accomplished by swapping it
with another pixel in its vicinity - so, first
store other pixel's RGB
*/
pP2 = &srcarray[ynew][xnew];
r1 = PPM_GETR(*pP2);
g1 = PPM_GETG(*pP2);
b1 = PPM_GETB(*pP2);
/* set second pixel to new value */
pP2 = &destarray[ynew][xnew];
PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP));
/* now, set first pixel to (old) value of second */
pP2 = &destarray[row][col];
PPM_ASSIGN(*pP2, r1, g1, b1);
} else {
/* displaced pixel is out of bounds; leave the old
pixel there
*/
pP2 = &destarray[row][col];
PPM_ASSIGN(*pP2, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP));
}
++pP;
}
}
ppm_writeppm(stdout, destarray, cols, rows, maxval, 0);
pm_close(ifP);
ppm_freearray(srcarray, rows);
ppm_freearray(destarray, rows);
return 0;
}
|
