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scale_image.c
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scale_image.c
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#include "header.h"
void scale_image(
int *image_arr1,
int width1,
int height1,
int *image_arr2,
int width2,
int height2,
char *method,
char *gaussian
)
{
int *imageb_arr1;
double factor_x;
double factor_y;
double zoom_sigma_zero= 0.6;
double sigma_x;
double sigma_y;
int precision= 5;
int debug_flag= 0;
int err_flag;
int i1;
int j1;
int pixel1;
if ( debug_flag == 1 ) {
/*
Print image_arr1
*/
err_flag= write_image(
(char *)"image_arr1.png",
image_arr1,
width1,
height1
);
if ( err_flag == 1 ) {
error_handler((char *)"scale_image");
}
}
factor_x= (double)width2/(double)width1;
factor_y= (double)height2/(double)height1;
if ( factor_x < 1.0 ) {
/*
We are downsampling along the x direction
This requires a Gaussian blur in the x direction
*/
sigma_x= zoom_sigma_zero*sqrt(1./(factor_x*factor_x)-1.);
}
else {
/*
We are upampling along the x direction
This doesn not require a Gaussian blur in the x direction
We are gonna apply a Gaussian blur in the x direction
using a very small sigma in the x direction
*/
sigma_x= 0.00001;
}
if ( factor_y < 1.0 ) {
/*
We are downsampling along the y direction
This requires a Gaussian blur in the y direction
*/
sigma_y= zoom_sigma_zero*sqrt(1./(factor_y*factor_y)-1.);
}
else {
/*
We are upampling along the y direction
This doesn not require a Gaussian blur in the y direction
We are gonna apply a Gaussian blur in the y direction
using a very small sigma in the y direction
*/
sigma_y= 0.00001;
}
if ( strcmp(gaussian,"yes") == 0 ) {
/*
Apply a Gaussian blur to image_arr1
*/
imageb_arr1= (int *)calloc(width1*height1,sizeof(int));
gaussian_blur_image_2(
image_arr1,
width1,
height1,
sigma_x,
sigma_y,
precision,
imageb_arr1
);
}
else if ( strcmp(gaussian,"no") == 0 ) {
/*
Do not apply a Gaussian blur to image_arr1
*/
imageb_arr1= (int *)calloc(width1*height1,sizeof(int));
for ( i1= 0 ; i1< height1 ; i1++ ) {
for ( j1= 0 ; j1< width1 ; j1++ ) {
pixel1= i1*width1+j1;
imageb_arr1[pixel1]= image_arr1[pixel1];
}
}
}
else {
error_handler((char *)"scale_image");
}
if ( debug_flag == 1 ) {
/*
Print imageb_arr1
*/
err_flag= write_image(
(char *)"imageb_arr1.png",
imageb_arr1,
width1,
height1
);
if ( err_flag == 1 ) {
error_handler((char *)"scale_image");
}
}
/*
Scale down imageb_arr1
*/
if ( strcmp(method,"nearest_neighbor") == 0 ) {
scale_image_nearest_neighbor(
imageb_arr1,
width1,
height1,
image_arr2,
width2,
height2
);
}
else if ( strcmp(method,"linear") == 0 ) {
scale_image_linear(
imageb_arr1,
width1,
height1,
image_arr2,
width2,
height2
);
}
else if ( strcmp(method,"cubic") == 0 ) {
scale_image_cubic(
imageb_arr1,
width1,
height1,
image_arr2,
width2,
height2
);
}
else {
error_handler((char *)"scale_image");
}
if ( debug_flag == 1 ) {
/*
Print image_arr2
*/
err_flag= write_image(
(char *)"image_arr2.png",
image_arr2,
width2,
height2
);
if ( err_flag == 1 ) {
error_handler((char *)"scale_image");
}
}
/*
Free imageb_arr1
*/
free(imageb_arr1);
}