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#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <math.h>
#include <values.h>
#include <string.h>
#include <unistd.h>
#include <ppm.h>
/* PPM and PGM utilities */
/* David Squire 990520 */
double *ppm_local_normalize(PPM *im_input, int window_size, double (*variance_transformer)(double)) {
int width, height;
int i, j, x, y, n;
double *dbl_image;
double pixel, sum, sum_squares, mean, variance, normalized_pixel;
char comment[80];
if ((im_input->type == PPM_ASC) || (im_input->type == PPM_RAW)) {
fprintf(stderr, "Can't normalize a PPM image!\n");
return (NULL);
}
/* allocate space for the normalized image */
width = im_input->width;
height = im_input->height;
dbl_image = (double *)malloc(width*height*sizeof(double));
/* move across the image, normalizing each pizel based on the
* statistics of the surrounding (square) window */
for (x = 0; x < width; x++) {
for (y = 0; y < height; y++) {
/* calculate the statistics for the window */
n = 0;
sum = sum_squares = 0;
for (i = -window_size/2; i < window_size/2; i++) {
for (j = -window_size/2; j < window_size/2; j++) {
if (((x + i) >= 0) && ((x + i) < width)
&& ((y + j) >= 0) && ((y + j) < height)) {
n++;
pixel = (double)(im_input->pixel[(y + j)*width + (x + i)])/255.0;
sum += pixel;
sum_squares += pixel*pixel;
}
}
}
mean = sum/(double)n;
variance = sum_squares/(double)n - mean*mean;
dbl_image[y*width + x] = (((double)im_input->pixel[y*width + x])/255 - mean)/sqrt(variance_transformer(variance));
/* HACK: The mean should now be zero, and the variance 1, for each
* region (approximately). Clip any thing more than 4 std. devs.
* away from the mean, just to see if this improves visual
* appearance */
/*
if (dbl_image[y*width + x] > 4)
dbl_image[y*width + x] = 4;
if (dbl_image[y*width + x] < -4)
dbl_image[y*width + x] = -4;
*/
}
}
return (dbl_image);
}
PPM *ppm_double_to_byte(double *dbl_image, int width, int height) {
PPM *im_output;
int x, y;
double min = MAXFLOAT, max = -MAXFLOAT;
/* set up the output PGM image */
im_output = new_ppm();
im_output->type = PGM_RAW;
im_output->width = width;
im_output->height = height;
im_output->max_col_comp = 255; /* this is max. possible */
im_output->bytes_per_pixel = 1;
im_output->pixel = (byte *)malloc(im_output->width*im_output->height*sizeof(byte));
/* find the minimum and maximum values of the input image */
for (x = 0; x < width; x++) {
for (y = 0; y < height; y++) {
if (dbl_image[y*width + x] > max) {
max = dbl_image[y*width + x];
}
else {
if (dbl_image[y*width + x] < min)
min = dbl_image[y*width + x];
}
}
}
/* now copy the input image to the output image, normalizing to the
* range [0,255] */
for (x = 0; x < width; x++) {
for (y = 0; y < height; y++) {
im_output->pixel[y*width + x] = (byte)rint(255*(dbl_image[y*width + x] - min)/(max - min));
}
}
return(im_output);
}
PPM *ppm_norm_contrast(PPM *im_input) {
PPM *im_output;
int width, height;
int x, y;
double min = MAXFLOAT, max = -MAXFLOAT;
/* set up the output PGM image */
im_output = new_ppm();
im_output->type = PGM_RAW;
width = im_output->width = im_input->width;
height = im_output->height = im_input->height;
im_output->max_col_comp = 255; /* this is max. possible */
im_output->bytes_per_pixel = 1;
im_output->pixel = (byte *)malloc(im_output->width*im_output->height*sizeof(byte));
/* find the minimum and maximum values of the input image */
for (x = 0; x < width; x++) {
for (y = 0; y < height; y++) {
if (im_input->pixel[y*width + x] > max) {
max = im_input->pixel[y*width + x];
}
else {
if (im_input->pixel[y*width + x] < min)
min = im_input->pixel[y*width + x];
}
}
}
/* now copy the input image to the output image, normalizing to the
* range [0,255] */
for (x = 0; x < width; x++) {
for (y = 0; y < height; y++) {
im_output->pixel[y*width + x] = (byte)rint(255*(im_input->pixel[y*width + x] - min)/(max - min));
}
}
return(im_output);
}
PPM *ppm_local_norm_contrast(PPM *im_input, int window_size) {
PPM *im_output;
int width, height;
int i, j, x, y;
byte pixel;
double max, min, sum, n;
char comment[80];
if ((im_input->type == PPM_ASC) || (im_input->type == PPM_RAW)) {
fprintf(stderr, "Can't normalize a PPM image!\n");
return (NULL);
}
/* set up the output PGM image */
im_output = new_ppm();
im_output->type = PGM_RAW;
width = im_output->width = im_input->width;
height = im_output->height = im_input->height;
im_output->max_col_comp = 255; /* this is max. possible */
im_output->bytes_per_pixel = 1;
im_output->pixel = (byte *)malloc(im_output->width*im_output->height*sizeof(byte));
for (x = 0; x < width; x++) {
for (y = 0; y < height; y++) {
/* calculate the max and min pixel the window */
min = 255;
max = 0;
sum = n = 0;
for (i = -window_size/2; i < window_size/2; i++) {
for (j = -window_size/2; j < window_size/2; j++) {
if (((x + i) >= 0) && ((x + i) < width)
&& ((y + j) >= 0) && ((y + j) < height)) {
pixel = im_input->pixel[(y + j)*width + (x + i)];
sum += pixel;
n++;
if (pixel > max)
max = pixel;
if (pixel < min)
min = pixel;
}
}
}
im_output->pixel[y*width + x] = 128 + (byte)rint(127*((double)(im_input->pixel[y*width + x]) - sum/n)/(max - min));
}
}
return (im_output);
}
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