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edges.c
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/***************************
*
* edges.c
* COMPOSITE FILE COMPRISING:
* edge.c
* edge2.c
* edge3.c
*
***************************\
/***********************************************
*
* file edge.c
*
* Functions: This file contains
* detect_edges
* setup_masks
* get_edge_options
* perform_convolution
* quick_edge
*
* Purpose:
* These functions implement several
* types of basic edge detection.
*
* External Calls:
* utility.c - fix_edges
*
* Modifications:
* 27 January 1991 - created
* 27 December 1992 - Fixed an error in
* how I did the 8 direction edge
* detectors. I was only detecting
* edges in the last (the 7)
* direction. I fixed this by
* setting the out_image to the sum
* only if the sum was greater than
* the out_image. This is in the
* function perform_convolution.
* 22 April 1998 - added capability to
* work an entire image at one time.
*
*************************************************/
#include "cips.h"
int fix_edges();
short quick_mask[3][3] = {
{-1, 0, -1},
{ 0, 4, 0},
{-1, 0, -1} };
/***************************
*
* Directions for the masks
* 3 2 1
* 4 x 0
* 5 6 7
*
****************************/
/* masks for kirsch operator */
short kirsch_mask_0[3][3] = {
{ 5, 5, 5},
{-3, 0, -3},
{-3, -3, -3} };
short kirsch_mask_1[3][3] = {
{-3, 5, 5},
{-3, 0, 5},
{-3, -3, -3} };
short kirsch_mask_2[3][3] = {
{-3, -3, 5},
{-3, 0, 5},
{-3, -3, 5} };
short kirsch_mask_3[3][3] = {
{-3, -3, -3},
{-3, 0, 5},
{-3, 5, 5} };
short kirsch_mask_4[3][3] = {
{-3, -3, -3},
{-3, 0, -3},
{ 5, 5, 5} };
short kirsch_mask_5[3][3] = {
{-3, -3, -3},
{ 5, 0, -3},
{ 5, 5, -3} };
short kirsch_mask_6[3][3] = {
{ 5, -3, -3},
{ 5, 0, -3},
{ 5, -3, -3} };
short kirsch_mask_7[3][3] = {
{ 5, 5, -3},
{ 5, 0, -3},
{-3, -3, -3} };
/* masks for prewitt operator */
short prewitt_mask_0[3][3] = {
{ 1, 1, 1},
{ 1, -2, 1},
{-1, -1, -1} };
short prewitt_mask_1[3][3] = {
{ 1, 1, 1},
{ 1, -2, -1},
{ 1, -1, -1} };
short prewitt_mask_2[3][3] = {
{ 1, 1, -1},
{ 1, -2, -1},
{ 1, 1, -1} };
short prewitt_mask_3[3][3] = {
{ 1, -1, -1},
{ 1, -2, -1},
{ 1, 1, 1} };
short prewitt_mask_4[3][3] = {
{-1, -1, -1},
{ 1, -2, 1},
{ 1, 1, 1} };
short prewitt_mask_5[3][3] = {
{-1, -1, 1},
{-1, -2, 1},
{ 1, 1, 1} };
short prewitt_mask_6[3][3] = {
{-1, 1, 1},
{-1, -2, 1},
{-1, 1, 1} };
short prewitt_mask_7[3][3] = {
{ 1, 1, 1},
{-1, -2, 1},
{-1, -1, 1} };
/* masks for sobel operator */
short sobel_mask_0[3][3] = {
{ 1, 2, 1},
{ 0, 0, 0},
{-1, -2, -1} };
short sobel_mask_1[3][3] = {
{ 2, 1, 0},
{ 1, 0, -1},
{ 0, -1, -2} };
short sobel_mask_2[3][3] = {
{ 1, 0, -1},
{ 2, 0, -2},
{ 1, 0, -1} };
short sobel_mask_3[3][3] = {
{ 0, -1, -2},
{ 1, 0, -1},
{ 2, 1, 0} };
short sobel_mask_4[3][3] = {
{-1, -2, -1},
{ 0, 0, 0},
{ 1, 2, 1} };
short sobel_mask_5[3][3] = {
{-2, -1, 0},
{-1, 0, 1},
{ 0, 1, 2} };
short sobel_mask_6[3][3] = {
{-1, 0, 1},
{-2, 0, 2},
{-1, 0, 1} };
short sobel_mask_7[3][3] = {
{ 0, 1, 2},
{-1, 0, 1},
{-2, -1, 0} };
/***********************************************
*
* setup_masks(...
*
* This function copies the mask values defined
* at the top of this file into the mask
* arrays mask_0 through mask_7.
*
***********************************************/
int setup_masks(detect_type, mask_0, mask_1, mask_2, mask_3,
mask_4, mask_5, mask_6, mask_7)
int detect_type;
short mask_0[3][3],
mask_1[3][3],
mask_2[3][3],
mask_3[3][3],
mask_4[3][3],
mask_5[3][3],
mask_6[3][3],
mask_7[3][3];
{
int i, j;
if(detect_type == KIRSCH){
for(i=0; i<3; i++){
for(j=0; j<3; j++){
mask_0[i][j] = kirsch_mask_0[i][j];
mask_1[i][j] = kirsch_mask_1[i][j];
mask_2[i][j] = kirsch_mask_2[i][j];
mask_3[i][j] = kirsch_mask_3[i][j];
mask_4[i][j] = kirsch_mask_4[i][j];
mask_5[i][j] = kirsch_mask_5[i][j];
mask_6[i][j] = kirsch_mask_6[i][j];
mask_7[i][j] = kirsch_mask_7[i][j];
}
}
} /* ends if detect_type == KIRSCH */
if(detect_type == PREWITT){
for(i=0; i<3; i++){
for(j=0; j<3; j++){
mask_0[i][j] = prewitt_mask_0[i][j];
mask_1[i][j] = prewitt_mask_1[i][j];
mask_2[i][j] = prewitt_mask_2[i][j];
mask_3[i][j] = prewitt_mask_3[i][j];
mask_4[i][j] = prewitt_mask_4[i][j];
mask_5[i][j] = prewitt_mask_5[i][j];
mask_6[i][j] = prewitt_mask_6[i][j];
mask_7[i][j] = prewitt_mask_7[i][j];
}
}
} /* ends if detect_type == PREWITT */
if(detect_type == SOBEL){
for(i=0; i<3; i++){
for(j=0; j<3; j++){
mask_0[i][j] = sobel_mask_0[i][j];
mask_1[i][j] = sobel_mask_1[i][j];
mask_2[i][j] = sobel_mask_2[i][j];
mask_3[i][j] = sobel_mask_3[i][j];
mask_4[i][j] = sobel_mask_4[i][j];
mask_5[i][j] = sobel_mask_5[i][j];
mask_6[i][j] = sobel_mask_6[i][j];
mask_7[i][j] = sobel_mask_7[i][j];
}
}
} /* ends if detect_type == SOBEL */
return(1);
} /* ends setup_masks */
/**********************************************************
*
* perform_convolution(...
*
* This function performs convolution between the input
* image and 8 3x3 masks. The result is placed in
* the out_image.
*
********************************************************/
int perform_convolution(image, out_image,
detect_type, threshold,
rows, cols, bits_per_pixel, high)
short **image,
**out_image;
int detect_type, high, threshold;
long rows, cols, bits_per_pixel;
{
char response[80];
int a,
b,
i,
is_present,
j,
sum;
short mask_0[3][3],
mask_1[3][3],
mask_2[3][3],
mask_3[3][3],
mask_4[3][3],
mask_5[3][3],
mask_6[3][3],
mask_7[3][3],
max,
min,
new_hi,
new_low;
setup_masks(detect_type, mask_0, mask_1,
mask_2, mask_3, mask_4, mask_5,
mask_6, mask_7);
new_hi = 250;
new_low = 16;
if(bits_per_pixel == 4){
new_hi = 10;
new_low = 3;
}
min = 0;
max = 255;
if(bits_per_pixel == 4)
max = 16;
/* clear output image array */
for(i=0; i<rows; i++)
for(j=0; j<cols; j++)
out_image[i][j] = 0;
printf("\n ");
for(i=1; i<rows-1; i++){
if( (i%10) == 0){ printf("%4d", i); }
for(j=1; j<cols-1; j++){
/* Convolve for all 8 directions */
/* 0 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] *
mask_0[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
/* 1 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] * mask_1[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
/* 2 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] * mask_2[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
/* 3 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] * mask_3[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
/* 4 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] * mask_4[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
/* 5 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] * mask_5[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
/* 6 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] * mask_6[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
/* 7 direction */
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum + image[i+a][j+b] * mask_7[a+1][b+1];
}
}
if(sum > max) sum = max;
if(sum < 0) sum = 0;
/* Correction 12-27-92
see file header for
details. */
if(sum > out_image[i][j])
out_image[i][j] = sum;
} /* ends loop over j */
} /* ends loop over i */
/* if desired, threshold the output image */
if(threshold == 1){
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
if(out_image[i][j] > high){
out_image[i][j] = new_hi;
}
else{
out_image[i][j] = new_low;
}
}
}
} /* ends if threshold == 1 */
return(1);
} /* ends perform_convolution */
/*******************************************
*
* quick_edge(...
*
* This function finds edges by using
* a single 3x3 mask.
*
*******************************************/
int quick_edge(the_image, out_image,
threshold, high, rows, cols, bits_per_pixel)
int high, threshold;
long rows, cols, bits_per_pixel;
short **the_image, **out_image;
{
short a, b, i, j, k,
length, max, new_hi, new_low,
sum, width;
new_hi = 250;
new_low = 16;
if(bits_per_pixel == 4){
new_hi = 10;
new_low = 3;
}
max = 255;
if(bits_per_pixel == 4)
max = 16;
/* Do convolution over image array */
printf("\n");
for(i=1; i<rows-1; i++){
if( (i%10) == 0) printf("%d ", i);
for(j=1; j<cols-1; j++){
sum = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum = sum +
the_image[i+a][j+b] *
quick_mask[a+1][b+1];
}
}
if(sum < 0) sum = 0;
if(sum > max) sum = max;
out_image[i][j] = sum;
} /* ends loop over j */
} /* ends loop over i */
/* if desired, threshold the output image */
if(threshold == 1){
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
if(out_image[i][j] > high){
out_image[i][j] = new_hi;
}
else{
out_image[i][j] = new_low;
}
}
}
} /* ends if threshold == 1 */
fix_edges(out_image, 1,
rows-1, cols-1);
return(1);
} /* ends quick_edge */
/**************************************************
*
* detect_edges(...
*
* This function detects edges in an area of one
* image and sends the result to another image
* on disk. It reads the input image from disk,
* calls a convolution function, and then writes
* the result out to disk. If needed, it
* allocates space on disk for the output image.
*
***************************************************/
int detect_edges(the_image, out_image,
detect_type, threshold, high,
rows, cols, bits_per_pixel)
int detect_type, high, threshold;
long rows, cols, bits_per_pixel;
short **the_image, **out_image;
{
perform_convolution(the_image, out_image,
detect_type, threshold,
rows, cols,
bits_per_pixel,
high);
fix_edges(out_image, 1, rows, cols);
return(1);
} /* ends detect_edges */
/***********************************************
*
* file edge2.c
*
* Functions: This file contains
* homogeneity
* difference_edge
* contrast_edge
* range
* variance
*
* Purpose:
* These functions implement several
* types of advanced edge detection.
*
* External Calls:
* utility.c - sort_elements
*
* Modifications:
* 26 March 1991 - created
* 30 December 1992 - added the range and
* variance edge detectors.
* May 10, 1998 - modified routines to work
* with an entire image in one array.
*
*************************************************/
int sort_elements();
short e_mask[3][3] = {
{-9, 0, -9},
{ 0, 36, 0},
{-9, 0, -9} };
short contrast[3][3] = {
{ 1, 1, 1},
{ 1, 1, 1},
{ 1, 1, 1}};
/**************************************************
*
* homogeneity(...
*
* This function performs edge detection by looking
* for the absence of an edge. The center of a
* 3x3 area is replaced by the absolute value of
* the max difference between the center point
* and its 8 neighbors.
*
***************************************************/
int homogeneity(the_image, out_image,
rows, cols, bits_per_pixel,
threshold, high)
int high, threshold;
short **the_image, **out_image;
long rows, cols, bits_per_pixel;
{
int a, b, absdiff, absmax, diff, i, j,
length, max, max_diff, new_hi, new_low, width;
new_hi = 250;
new_low = 16;
if(bits_per_pixel == 4){
new_hi = 10;
new_low = 3;
}
max = 255;
if(bits_per_pixel == 4)
max = 16;
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
out_image[i][j] = 0;
}
}
for(i=1; i<rows-1; i++){
if( (i%10) == 0) printf("%4d", i);
for(j=1; j<cols-1; j++){
max_diff = 0;
for(a=-1; a<=1; a++){
for(b=-1; b<=1; b++){
diff = the_image[i][j] -
the_image[i+a][j+b];
absdiff = abs(diff);
if(absdiff > max_diff)
max_diff = absdiff;
} /* ends loop over b */
} /* ends loop over a */
out_image[i][j] = max_diff;
} /* ends loop over j */
} /* ends loop over i */
/* if desired, threshold the output image */
if(threshold == 1){
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
if(out_image[i][j] > high){
out_image[i][j] = new_hi;
}
else{
out_image[i][j] = new_low;
}
}
}
} /* ends if threshold == 1 */
return(1);
} /* ends homogeneity */
/**************************************************
*
* difference_edge(...
*
* This function performs edge detection by looking
* at the differences in the pixels that surround
* the center point of a 3x3 area. It replaces the
* center point with the absolute value of the
* max difference of:
* upper left - lower right
* upper right - lower left
* left - right
* top - bottom
*
***************************************************/
int difference_edge(the_image, out_image,
rows, cols, bits_per_pixel,
threshold, high)
int high, threshold;
short **the_image, **out_image;
long rows, cols, bits_per_pixel;
{
int a, b, absdiff, absmax, diff, i, j,
length, max, max_diff, new_hi, new_low, width;
new_hi = 250;
new_low = 16;
if(bits_per_pixel == 4){
new_hi = 10;
new_low = 3;
}
max = 255;
if(bits_per_pixel == 4)
max = 16;
for(i=0; i<rows; i++)
for(j=0; j<cols; j++)
out_image[i][j] = 0;
for(i=1; i<rows-1; i++){
if( (i%10) == 0) printf("%4d", i);
for(j=1; j<cols-1; j++){
max_diff = 0;
absdiff = abs(the_image[i-1][j-1] -
the_image[i+1][j+1]);
if(absdiff > max_diff) max_diff = absdiff;
absdiff = abs(the_image[i-1][j+1] -
the_image[i+1][j-1]);
if(absdiff > max_diff) max_diff = absdiff;
absdiff = abs(the_image[i][j-1] -
the_image[i][j+1]);
if(absdiff > max_diff) max_diff = absdiff;
absdiff = abs(the_image[i-1][j] -
the_image[i+1][j]);
if(absdiff > max_diff) max_diff = absdiff;
out_image[i][j] = max_diff;
} /* ends loop over j */
} /* ends loop over i */
/* if desired, threshold the output image */
if(threshold == 1){
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
if(out_image[i][j] > high){
out_image[i][j] = new_hi;
}
else{
out_image[i][j] = new_low;
}
}
}
} /* ends if threshold == 1 */
return(1);
} /* ends difference_edge */
/**************************************************
*
* contrast_edge(...
*
* The edge detector uses the basic quick edge
* detector mask and then divides the result
* by a contrast smooth mask. This implements
* Johnson's contrast based edge detector.
*
***************************************************/
int contrast_edge(the_image, out_image,
rows, cols, bits_per_pixel,
threshold, high)
int high, threshold;
short **the_image, **out_image;
long rows, cols, bits_per_pixel;
{
int ad, d;
int a, b, absdiff, absmax, diff, i, j,
length, max, new_hi, new_low,
sum_d, sum_n, width;
new_hi = 250;
new_low = 16;
if(bits_per_pixel == 4){
new_hi = 10;
new_low = 3;
}
max = 255;
if(bits_per_pixel == 4)
max = 16;
for(i=0; i<rows; i++)
for(j=0; j<cols; j++)
out_image[i][j] = 0;
for(i=1; i<rows-1; i++){
if( (i%10) == 0) printf("%4d", i);
for(j=1; j<cols-1; j++){
sum_n = 0;
sum_d = 0;
for(a=-1; a<2; a++){
for(b=-1; b<2; b++){
sum_n = sum_n + the_image[i+a][j+b] *
e_mask[a+1][b+1];
sum_d = sum_d + the_image[i+a][j+b] *
contrast[a+1][b+1];
}
}
d = sum_d / 9;
if(d == 0)
d = 1;
out_image[i][j] = sum_n/d;
if(out_image[i][j] > max)
out_image[i][j] = max;
if(out_image[i][j] < 0)
out_image[i][j] = 0;
} /* ends loop over j */
} /* ends loop over i */
/* if desired, threshold the output image */
if(threshold == 1){
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
if(out_image[i][j] > high){
out_image[i][j] = new_hi;
}
else{
out_image[i][j] = new_low;
}
}
}
} /* ends if threshold == 1 */
return(1);
} /* ends contrast_edge */
/*******************************************
*
* range(..
*
* This edge detector performs the
* range operation.
* It replaces the pixel at the center of a
* 3x3, 5x5, etc. area with the max - min
* for that area.
*
*******************************************/
int range(the_image, out_image,
rows, cols, bits_per_pixel,
size, threshold, high)
int high, threshold, size;
short **the_image,
**out_image;
long rows, cols, bits_per_pixel;
{
int a, b, count, i, j, k,
new_hi, new_low, length,
sd2, sd2p1, ss, width;
short *elements;
sd2 = size/2;
sd2p1 = sd2 + 1;
/**********************************************
*
* Allocate the elements array large enough
* to hold size*size shorts.
*
**********************************************/
ss = size*size;
elements = (short *) malloc(ss * sizeof(short));
new_hi = 250;
new_low = 16;
if(bits_per_pixel == 4){
new_hi = 10;
new_low = 3;
}
/***************************
*
* Loop over image array
*
****************************/
printf("\n");
for(i=sd2; i<rows-sd2; i++){
if( (i%10) == 0) printf("%4d ", i);
for(j=sd2; j<cols-sd2; j++){
count = 0;
for(a=-sd2; a<sd2p1; a++){
for(b=-sd2; b<sd2p1; b++){