// Advanced morphological operations kernels for GPU execution
// Includes hit-or-miss transform, skeleton, and other advanced operations
__kernel void hit_or_miss_2d(
__global const float* input,
__global const float* foreground_struct,
__global const float* background_struct,
__global float* output,
const int height,
const int width,
const int struct_height,
const int struct_width
) {
int x = get_global_id(0);
int y = get_global_id(1);
if (x >= width || y >= height) return;
int shalf_h = struct_height / 2;
int shalf_w = struct_width / 2;
bool foreground_match = true;
bool background_match = true;
// Check both foreground and background structures
for (int sy = 0; sy < struct_height; sy++) {
for (int sx = 0; sx < struct_width; sx++) {
int ix = x + sx - shalf_w;
int iy = y + sy - shalf_h;
// Skip if outside image boundaries
if (ix < 0 || ix >= width || iy < 0 || iy >= height) {
continue;
}
float pixel_val = input[iy * width + ix];
float fg_struct = foreground_struct[sy * struct_width + sx];
float bg_struct = background_struct[sy * struct_width + sx];
// Check foreground structure match
if (fg_struct > 0.5f) {
if (pixel_val < 0.5f) {
foreground_match = false;
}
}
// Check background structure match
if (bg_struct > 0.5f) {
if (pixel_val > 0.5f) {
background_match = false;
}
}
}
}
output[y * width + x] = (foreground_match && background_match) ? 1.0f : 0.0f;
}
__kernel void morphological_gradient_2d(
__global const float* input,
__global const float* structure,
__global float* output,
const int height,
const int width,
const int struct_height,
const int struct_width
) {
int x = get_global_id(0);
int y = get_global_id(1);
if (x >= width || y >= height) return;
int shalf_h = struct_height / 2;
int shalf_w = struct_width / 2;
float max_val = -INFINITY;
float min_val = INFINITY;
// Compute erosion and dilation simultaneously
for (int sy = 0; sy < struct_height; sy++) {
for (int sx = 0; sx < struct_width; sx++) {
if (structure[sy * struct_width + sx] > 0.0f) {
// Erosion coordinates
int ix_erosion = x + sx - shalf_w;
int iy_erosion = y + sy - shalf_h;
// Dilation coordinates (structure flipped)
int ix_dilation = x - sx + shalf_w;
int iy_dilation = y - sy + shalf_h;
// Erosion (minimum)
if (ix_erosion >= 0 && ix_erosion < width && iy_erosion >= 0 && iy_erosion < height) {
float val = input[iy_erosion * width + ix_erosion];
min_val = fmin(min_val, val);
}
// Dilation (maximum)
if (ix_dilation >= 0 && ix_dilation < width && iy_dilation >= 0 && iy_dilation < height) {
float val = input[iy_dilation * width + ix_dilation];
max_val = fmax(max_val, val);
}
}
}
}
// Morphological gradient = dilation - erosion
output[y * width + x] = max_val - min_val;
}
__kernel void tophat_transform_2d(
__global const float* input,
__global const float* structure,
__global float* output,
const int height,
const int width,
const int struct_height,
const int struct_width,
const int is_white_tophat // 1 for white tophat, 0 for black tophat
) {
int x = get_global_id(0);
int y = get_global_id(1);
if (x >= width || y >= height) return;
int shalf_h = struct_height / 2;
int shalf_w = struct_width / 2;
float max_val = -INFINITY;
float min_val = INFINITY;
float original_val = input[y * width + x];
// Compute erosion and dilation
for (int sy = 0; sy < struct_height; sy++) {
for (int sx = 0; sx < struct_width; sx++) {
if (structure[sy * struct_width + sx] > 0.0f) {
// Erosion coordinates
int ix_erosion = x + sx - shalf_w;
int iy_erosion = y + sy - shalf_h;
// Dilation coordinates (structure flipped)
int ix_dilation = x - sx + shalf_w;
int iy_dilation = y - sy + shalf_h;
// Erosion (minimum)
if (ix_erosion >= 0 && ix_erosion < width && iy_erosion >= 0 && iy_erosion < height) {
float val = input[iy_erosion * width + ix_erosion];
min_val = fmin(min_val, val);
}
// Dilation (maximum)
if (ix_dilation >= 0 && ix_dilation < width && iy_dilation >= 0 && iy_dilation < height) {
float val = input[iy_dilation * width + ix_dilation];
max_val = fmax(max_val, val);
}
}
}
}
if (is_white_tophat) {
// White tophat: original - opening (erosion followed by dilation)
// Approximation: original - dilation(erosion)
output[y * width + x] = original_val - max_val;
} else {
// Black tophat: closing - original (dilation followed by erosion)
// Approximation: erosion(dilation) - original
output[y * width + x] = min_val - original_val;
}
}
__kernel void skeleton_2d(
__global const float* input,
__global float* output,
__global float* temp_buffer,
const int height,
const int width,
const int iteration
) {
int x = get_global_id(0);
int y = get_global_id(1);
if (x >= width || y >= height) return;
float center = input[y * width + x];
if (center < 0.5f) {
output[y * width + x] = 0.0f;
return;
}
// Simple skeletonization using hit-or-miss transform patterns
// This is a simplified version - full implementation would use multiple patterns
// Check 3x3 neighborhood for thinning conditions
float neighbors[8];
int idx = 0;
for (int dy = -1; dy <= 1; dy++) {
for (int dx = -1; dx <= 1; dx++) {
if (dx == 0 && dy == 0) continue;
int nx = clamp(x + dx, 0, width - 1);
int ny = clamp(y + dy, 0, height - 1);
neighbors[idx++] = input[ny * width + nx];
}
}
// Count transitions from 0 to 1 in circular order
int transitions = 0;
for (int i = 0; i < 8; i++) {
int next = (i + 1) % 8;
if (neighbors[i] < 0.5f && neighbors[next] > 0.5f) {
transitions++;
}
}
// Count foreground neighbors
int fg_neighbors = 0;
for (int i = 0; i < 8; i++) {
if (neighbors[i] > 0.5f) {
fg_neighbors++;
}
}
// Zhang-Suen thinning conditions
bool condition1 = (fg_neighbors >= 2 && fg_neighbors <= 6);
bool condition2 = (transitions == 1);
bool condition3 = true; // Additional pattern-specific conditions would go here
if (condition1 && condition2 && condition3) {
output[y * width + x] = 0.0f; // Remove pixel
} else {
output[y * width + x] = center; // Keep pixel
}
}
__kernel void distance_transform_chamfer_2d(
__global const float* input,
__global float* output,
const int height,
const int width,
const int forward_pass // 1 for forward, 0 for backward
) {
int x = get_global_id(0);
int y = get_global_id(1);
if (x >= width || y >= height) return;
if (input[y * width + x] < 0.5f) {
output[y * width + x] = 0.0f;
return;
}
float min_dist = INFINITY;
if (forward_pass) {
// Forward pass: check neighbors from top-left
for (int dy = -1; dy <= 0; dy++) {
for (int dx = -1; dx <= 1; dx++) {
if (dx == 0 && dy == 0) continue;
if (dy == 0 && dx > 0) continue; // Skip right neighbors in forward pass
int nx = x + dx;
int ny = y + dy;
if (nx >= 0 && nx < width && ny >= 0 && ny < height) {
float neighbor_dist = output[ny * width + nx];
float edge_weight = (dx == 0 || dy == 0) ? 1.0f : 1.414213562f; // sqrt(2)
min_dist = fmin(min_dist, neighbor_dist + edge_weight);
}
}
}
} else {
// Backward pass: check neighbors from bottom-right
for (int dy = 0; dy <= 1; dy++) {
for (int dx = -1; dx <= 1; dx++) {
if (dx == 0 && dy == 0) continue;
if (dy == 0 && dx < 0) continue; // Skip left neighbors in backward pass
int nx = x + dx;
int ny = y + dy;
if (nx >= 0 && nx < width && ny >= 0 && ny < height) {
float neighbor_dist = output[ny * width + nx];
float edge_weight = (dx == 0 || dy == 0) ? 1.0f : 1.414213562f; // sqrt(2)
min_dist = fmin(min_dist, neighbor_dist + edge_weight);
}
}
}
}
if (min_dist != INFINITY) {
output[y * width + x] = min_dist;
}
}