144 lines
4.9 KiB
C++
144 lines
4.9 KiB
C++
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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#pragma once
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#include <algorithm>
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#include "util/image.h"
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#include "util/types.h"
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CCL_NAMESPACE_BEGIN
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namespace {
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template<typename T>
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const T *util_image_read(const vector<T> &pixels,
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const int64_t width,
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const int64_t /*height*/,
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const int64_t components,
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const int64_t x,
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const int64_t y)
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{
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const int64_t index = ((int64_t)y * width + (int64_t)x) * components;
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return &pixels[index];
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}
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template<typename T>
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void util_image_downscale_sample(const vector<T> &pixels,
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const int64_t width,
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const int64_t height,
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const int64_t components,
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const int64_t kernel_size,
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const float x,
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const float y,
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T *result)
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{
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assert(components <= 4);
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const int64_t ix = (int64_t)x;
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const int64_t iy = (int64_t)y;
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/* TODO(sergey): Support something smarter than box filer. */
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float accum[4] = {0};
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int64_t count = 0;
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for (int64_t dy = 0; dy < kernel_size; ++dy) {
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for (int64_t dx = 0; dx < kernel_size; ++dx) {
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const int64_t nx = ix + dx;
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const int64_t ny = iy + dy;
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if (nx >= width || ny >= height) {
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continue;
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}
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const T *pixel = util_image_read(pixels, width, height, components, nx, ny);
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for (size_t k = 0; k < components; ++k) {
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accum[k] += util_image_cast_to_float(pixel[k]);
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}
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++count;
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}
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}
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if (count != 0) {
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const float inv_count = 1.0f / (float)count;
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for (int64_t k = 0; k < components; ++k) {
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result[k] = util_image_cast_from_float<T>(accum[k] * inv_count);
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}
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}
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else {
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for (int64_t k = 0; k < components; ++k) {
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result[k] = T(0.0f);
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}
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}
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}
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template<typename T>
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void util_image_downscale_pixels(const vector<T> &input_pixels,
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const int64_t input_width,
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const int64_t input_height,
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const int64_t components,
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const float inv_scale_factor,
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const int64_t output_width,
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const int64_t output_height,
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vector<T> *output_pixels)
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{
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const int64_t kernel_size = (int64_t)(inv_scale_factor + 0.5f);
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for (int64_t y = 0; y < output_height; ++y) {
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for (int64_t x = 0; x < output_width; ++x) {
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const float input_x = (float)x * inv_scale_factor;
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const float input_y = (float)y * inv_scale_factor;
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const int64_t output_index = (y * output_width + x) * components;
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util_image_downscale_sample(input_pixels,
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input_width,
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input_height,
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components,
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kernel_size,
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input_x,
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input_y,
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&output_pixels->at(output_index));
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}
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}
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}
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} /* namespace */
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template<typename T>
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void util_image_resize_pixels(const vector<T> &input_pixels,
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const int64_t input_width,
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const int64_t input_height,
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const int64_t components,
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const float scale_factor,
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vector<T> *output_pixels,
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int64_t *output_width,
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int64_t *output_height)
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{
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/* Early output for case when no scaling is applied. */
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if (scale_factor == 1.0f) {
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*output_width = input_width;
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*output_height = input_height;
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*output_pixels = input_pixels;
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return;
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}
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/* First of all, we calculate output image dimensions.
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* We clamp them to be 1 pixel at least so we do not generate degenerate
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* image.
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*/
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*output_width = std::max((int64_t)((float)input_width * scale_factor), (int64_t)1);
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*output_height = std::max((int64_t)((float)input_height * scale_factor), (int64_t)1);
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/* Prepare pixel storage for the result. */
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const int64_t num_output_pixels = ((*output_width) * (*output_height)) * components;
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output_pixels->resize(num_output_pixels);
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if (scale_factor < 1.0f) {
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const float inv_scale_factor = 1.0f / scale_factor;
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util_image_downscale_pixels(input_pixels,
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input_width,
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input_height,
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components,
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inv_scale_factor,
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*output_width,
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*output_height,
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output_pixels);
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}
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else {
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/* TODO(sergey): Needs implementation. */
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}
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}
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CCL_NAMESPACE_END
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