openmv/lib/imlib/integral.c
iabdalkader daf2bb30da misc: Restructure repo.
Signed-off-by: iabdalkader <i.abdalkader@gmail.com>
2025-04-13 08:28:34 +02:00

128 lines
4.3 KiB
C

/*
* SPDX-License-Identifier: MIT
*
* Copyright (C) 2013-2024 OpenMV, LLC.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* Integral image.
*/
#include <stdlib.h>
#include <string.h>
#include <arm_math.h>
#include "imlib.h"
#include "fb_alloc.h"
void imlib_integral_image_alloc(i_image_t *sum, int w, int h) {
sum->w = w;
sum->h = h;
sum->data = fb_alloc(w * h * sizeof(*sum->data), FB_ALLOC_NO_HINT);
}
void imlib_integral_image_free(i_image_t *sum) {
// 1 allocation
fb_free();
}
void imlib_integral_image(image_t *src, i_image_t *sum) {
typeof(*src->data) * img_data = src->data;
typeof(*sum->data) * sum_data = sum->data;
// Compute first column to avoid branching
for (int s = 0, x = 0; x < src->w; x++) {
/* sum of the current row (integer) */
s += img_data[x];
sum_data[x] = s;
}
for (int y = 1; y < src->h; y++) {
/* loop over the number of columns */
for (int s = 0, x = 0; x < src->w; x++) {
/* sum of the current row (integer) */
s += img_data[y * src->w + x];
sum_data[y * src->w + x] = s + sum_data[(y - 1) * src->w + x];
}
}
}
void imlib_integral_image_scaled(image_t *src, i_image_t *sum) {
typeof(*src->data) * img_data = src->data;
typeof(*sum->data) * sum_data = sum->data;
int x_ratio = (int) ((src->w << 16) / sum->w) + 1;
int y_ratio = (int) ((src->h << 16) / sum->h) + 1;
// Compute first column to avoid branching
for (int s = 0, x = 0; x < sum->w; x++) {
int sx = (x * x_ratio) >> 16;
/* sum of the current row (integer) */
s += img_data[sx];
sum_data[x] = s;
}
for (int y = 1; y < sum->h; y++) {
int sy = (y * y_ratio) >> 16;
/* loop over the number of columns */
for (int s = 0, x = 0; x < sum->w; x++) {
int sx = (x * x_ratio) >> 16;
/* sum of the current row (integer) */
s += img_data[sy * src->w + sx];
sum_data[y * sum->w + x] = s + sum_data[(y - 1) * sum->w + x];
}
}
}
void imlib_integral_image_sq(image_t *src, i_image_t *sum) {
typeof(*src->data) * img_data = src->data;
typeof(*sum->data) * sum_data = sum->data;
// Compute first column to avoid branching
for (uint32_t s = 0, x = 0; x < src->w; x++) {
/* sum of the current row (integer) */
s += img_data[x] * img_data[x];
sum_data[x] = s;
}
for (uint32_t y = 1; y < src->h; y++) {
/* loop over the number of columns */
for (uint32_t s = 0, x = 0; x < src->w; x++) {
/* sum of the current row (integer) */
s += img_data[y * src->w + x] * img_data[y * src->w + x];
sum_data[y * src->w + x] = s + sum_data[(y - 1) * src->w + x];
}
}
}
uint32_t imlib_integral_lookup(i_image_t *sum, int x, int y, int w, int h) {
#define PIXEL_AT(x, y) \
(sum->data[((y) - 1) * sum->w + ((x) - 1)])
if (x == 0 && y == 0) {
return PIXEL_AT(w, h);
} else if (y == 0) {
return PIXEL_AT(w + x, h) - PIXEL_AT(x, h);
} else if (x == 0) {
return PIXEL_AT(w, h + y) - PIXEL_AT(w, y);
} else {
return PIXEL_AT(w + x, h + y) + PIXEL_AT(x, y) - PIXEL_AT(w + x, y) - PIXEL_AT(x, h + y);
}
#undef PIXEL_AT
}