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Some attempts at fixing grayscale blue-noise

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This commit is contained in:
Stephen Seo 2021-10-07 15:34:13 +09:00
parent a8f0ec788a
commit 73aa21e92a
3 changed files with 221 additions and 33 deletions
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99
src/blue_noise.cpp
View file

@ -113,7 +113,21 @@ image::Bl dither::blue_noise_grayscale(int width, int height, int threads) {
int filter_size = (width + height) / 2;
std::vector<float> precomputed(internal::precompute_gaussian(filter_size));
// TODO DEBUG
//float pmax = 0.01F;
//for(float value : precomputed) {
// if(value > pmax) {
// pmax = value;
// }
//}
//for(float &value: precomputed) {
// value /= pmax;
//}
//return image::Bl(precomputed, filter_size);
int min, max, min2, max2;
int prevmax = -1;
int prevmax2 = -1;
float tempPixel;
while(true) {
printf("Iteration %d\n", iterations);
@ -121,9 +135,14 @@ image::Bl dither::blue_noise_grayscale(int width, int height, int threads) {
internal::compute_filter_grayscale(image,
width, height, count,
filter_size, filter_out,
&precomputed, threads);
&precomputed, 0);
std::tie(min, max) = internal::filter_minmax(filter_out);
//std::tie(std::ignore, max) = internal::filter_minmax_in_range(max,
// width,
// height,
// 7,
// filter_out);
printf("min == %4d, max == %4d", min, max);
tempPixel = image[max];
image[max] = 0.0F;
@ -131,18 +150,33 @@ image::Bl dither::blue_noise_grayscale(int width, int height, int threads) {
internal::compute_filter_grayscale(image,
width, height, count,
filter_size, filter_out,
&precomputed, threads);
&precomputed, 0);
std::tie(min2, max2) = internal::filter_minmax(filter_out);
//std::tie(min2, std::ignore) = internal::filter_minmax_in_range(min2,
// width,
// height,
// 7,
// filter_out);
printf(", min2 == %4d, max2 == %4d\n", min2, max2);
if(utility::dist(min, min2, width) < 1.5F) {
image[max] = image[min2];
image[min2] = tempPixel;
} else {
if(min2 != min) {
image[max] = tempPixel;
break;
} else {
image[max] = image[min];
image[min] = tempPixel;
}
//if(prevmax == max && prevmax2 == max2) {
// image[max] = tempPixel;
// break;
//} else {
// image[max] = image[min2];
// image[min2] = tempPixel;
//}
prevmax = max;
prevmax2 = max2;
//#ifndef NDEBUG
if(iterations % 20 == 0) {
@ -156,13 +190,62 @@ image::Bl dither::blue_noise_grayscale(int width, int height, int threads) {
name.append(std::to_string(iterations));
name.append(".pgm");
image::Bl(image, width).writeToFile(image::file_type::PGM, true, name);
name.clear();
name.append("tempFilter");
if(iterations < 10) {
name.append("00");
} else if(iterations < 100) {
name.append("0");
}
name.append(std::to_string(iterations));
name.append(".pgm");
internal::compute_filter_grayscale(image,
width, height, count,
filter_size, filter_out,
&precomputed, 0);
std::vector<float> normalizedFilter(filter_out);
float fmax = -std::numeric_limits<float>::infinity();
float fmin = std::numeric_limits<float>::infinity();
for(float value : normalizedFilter) {
if(value > fmax) {
fmax = value;
}
if(value < fmin) {
fmin = value;
}
}
fmax -= fmin;
for(float &value : normalizedFilter) {
value = (value - fmin) / fmax;
}
image::Bl(normalizedFilter, width).writeToFile(image::file_type::PGM, true, name);
}
//#endif
++iterations;
}
// TODO
internal::compute_filter_grayscale(image,
width, height, count,
filter_size, filter_out,
&precomputed, 0);
std::vector<float> normalizedFilter(filter_out);
float fmax = -std::numeric_limits<float>::infinity();
float fmin = std::numeric_limits<float>::infinity();
for(float value : normalizedFilter) {
if(value > fmax) {
fmax = value;
}
if(value < fmin) {
fmin = value;
}
}
fmax -= fmin;
for(float &value : normalizedFilter) {
value = (value - fmin) / fmax;
}
image::Bl(normalizedFilter, width).writeToFile(image::file_type::PGM, true, "filterOut.pgm");
return image::Bl(image, width);
}

115
src/blue_noise.hpp
View file

@ -12,6 +12,9 @@
#include <queue>
#include <random>
#include <cassert>
#include <stdexcept>
#include <sys/sysinfo.h>
#include <CL/opencl.h>
@ -64,7 +67,7 @@ namespace internal {
for(unsigned int i = 0; i < size; ++i) {
graynoise.push_back(static_cast<float>(i) / static_cast<float>(size - 1));
//graynoise[i] = dist(re);
//graynoise.push_back(dist(re));
}
for(unsigned int i = 0; i < size - 1; ++i) {
std::uniform_int_distribution<unsigned int> range(i + 1, size - 1);
@ -77,10 +80,12 @@ namespace internal {
return graynoise;
}
constexpr float mu_squared = 1.5f * 1.5f;
constexpr float mu = 1.5F;
constexpr float mu_squared = mu * mu;
constexpr float double_mu_squared = 2.0F * mu * mu;
inline float gaussian(float x, float y) {
return std::exp(-(x*x + y*y)/(2*mu_squared));
return std::exp(-(x*x + y*y)/(double_mu_squared));
}
inline std::vector<float> precompute_gaussian(int size) {
@ -90,7 +95,8 @@ namespace internal {
for(int i = 0; i < size * size; ++i) {
auto xy = utility::oneToTwo(i, size);
precomputed.push_back(gaussian(
(float)xy.first - size / 2.0f, (float)xy.second - size / 2.0f));
(float)xy.first - (float)size / 2.0f,
(float)xy.second - (float)size / 2.0f));
}
return precomputed;
@ -166,11 +172,14 @@ namespace internal {
float sum = 0.0F;
for(int q = 0; q < filter_size; ++q) {
int q_prime = (height + filter_size / 2 + y - q) % height;
int q_prime = (height - filter_size / 2 + y + q) % height;
for(int p = 0; p < filter_size; ++p) {
int p_prime = (width + filter_size / 2 + x - p) % width;
int p_prime = (width - filter_size / 2 + x + p) % width;
sum += image[utility::twoToOne(p_prime, q_prime, width, height)]
* precomputed[utility::twoToOne(p, q, filter_size, filter_size)];
* precomputed[utility::twoToOne(p,
q,
filter_size,
filter_size)];
}
}
@ -277,6 +286,7 @@ namespace internal {
int count, int filter_size, std::vector<float> &filter_out,
const std::vector<float> *precomputed = nullptr,
int threads = 1) {
if(threads == 1) {
if(precomputed) {
for(int y = 0; y < height; ++y) {
for(int x = 0; x < width; ++x) {
@ -300,11 +310,62 @@ namespace internal {
}
}
}
} else {
if(threads == 0) {
threads = get_nprocs();
if(threads == 0) {
throw std::runtime_error("0 threads detected, "
"should be impossible");
}
}
if(precomputed) {
const auto tfn = [] (unsigned int ymin, unsigned int ymax,
unsigned int width, unsigned int height,
unsigned int filter_size,
const std::vector<float> *const image,
std::vector<float> *const filter_out,
const std::vector<float> *const precomputed) {
for(unsigned int y = ymin; y < ymax; ++y) {
for(unsigned int x = 0; x < width; ++x) {
(*filter_out)[utility::twoToOne(x, y, width, height)] =
internal::filter_with_precomputed_grayscale(
*image,
x, y,
width, height,
filter_size,
*precomputed);
}
}
};
unsigned int step = height / threads;
std::vector<std::thread> threadHandles;
for(int i = 0; i < threads; ++i) {
unsigned int starty = i * step;
unsigned int endy = (i + 1) * step;
if(i + 1 == threads) {
endy = height;
}
threadHandles.emplace_back(tfn, starty, endy,
width, height,
filter_size,
&image,
&filter_out,
precomputed);
}
for(int i = 0; i < threads; ++i) {
threadHandles[i].join();
}
} else {
// TODO unimplemented
throw std::runtime_error("Unimplemented");
}
}
}
inline std::pair<int, int> filter_minmax(const std::vector<float>& filter) {
float min = std::numeric_limits<float>::infinity();
float max = 0.0f;
float max = -std::numeric_limits<float>::infinity();
int min_index = 0;
int max_index = 0;
@ -416,6 +477,44 @@ namespace internal {
return bwImage;
}
inline std::pair<int, int> filter_minmax_in_range(int start, int width,
int height,
int range,
const std::vector<float> &vec) {
float max = -std::numeric_limits<float>::infinity();
float min = std::numeric_limits<float>::infinity();
int maxIdx = -1;
int minIdx = -1;
auto startXY = utility::oneToTwo(start, width);
for(int y = startXY.second - range / 2; y <= startXY.second + range / 2; ++y) {
for(int x = startXY.first - range / 2; x <= startXY.first + range / 2; ++x) {
int idx = utility::twoToOne(x, y, width, height);
if(idx == start) {
continue;
}
if(vec[idx] < min) {
min = vec[idx];
minIdx = idx;
}
if(vec[idx] > max) {
max = vec[idx];
maxIdx = idx;
}
}
}
if(minIdx < 0) {
throw std::runtime_error("Invalid minIdx value");
} else if(maxIdx < 0) {
throw std::runtime_error("Invalid maxIdx value");
}
return {minIdx, maxIdx};
}
} // namespace dither::internal
} // namespace dither

6
src/utility.hpp
View file

@ -6,6 +6,12 @@
namespace utility {
inline int twoToOne(int x, int y, int width, int height) {
while(x < 0) {
x += width;
}
while(y < 0) {
y += height;
}
x = x % width;
y = y % height;
return x + y * width;