seam-carving/src/seam-carving.cpp

597 lines
25 KiB
C++

#include <cassert>
#include <iostream>
#include <random>
#include <string>
#include <vector>
// Command-line parsing
#include <CLI11.hpp>
// Image filtering and I/O
#include "image.h"
#include "utils.hpp"
#include <SimpleProgressBar.hpp>
#define DEFAULT_SEAMS 1
// Global flags
bool silent = false;
bool show_seams = false;
bool until_mask_removal = false;
int max_step = 1;
std::string function = "grad";
void export_image(const char *filename, const void *data, int width, int height,
int nbChannels) {
if (!silent)
std::cout << "Exporting to \"" << filename << "\".." << std::endl;
int errcode = stbi_write_png(filename, width, height, nbChannels, data,
nbChannels * width);
if (!errcode) {
std::cerr << "Error while exporting the resulting image." << std::endl;
exit(errcode);
}
}
#define compute_energy_for_pixel( \
source, width, height, i, j, \
nbChannels, /* computes the energy at pixel i,j, i.e. energy[width*j+i]*/ \
nbColorChannels, dest) { \
auto indexPixel = (nbChannels) * (width * (j) + (i)); \
auto indexPixel_up = \
((j) - 1 > 0) ? (nbChannels) * (width * ((j) - 1) + (i)) : indexPixel; \
auto indexPixel_down = ((j) + 1 < height) \
? (nbChannels) * (width * ((j) + 1) + (i)) \
: indexPixel; \
auto indexPixel_left = \
((i) - 1 > 0) ? (nbChannels) * (width * (j) + ((i) - 1)) : indexPixel; \
auto indexPixel_right = ((i) + 1 < width) \
? (nbChannels) * (width * (j) + ((i) + 1)) \
: indexPixel; \
dest = 0; \
if (function == "grad") { \
for (auto ch = 0; ch < (nbColorChannels); ch++) { \
dest += ((fabs((float)source[indexPixel_up + ch] - \
source[indexPixel + ch])) + \
\
(fabs((float)source[indexPixel_down + ch] - \
source[indexPixel + ch])) + \
\
(fabs((float)source[indexPixel_left + ch] - \
source[indexPixel + ch])) + \
(fabs((float)source[indexPixel_right + ch] - \
source[indexPixel + ch]))); \
} \
} else if (function == "gradnorm") { \
for (auto ch = 0; ch < (nbColorChannels); ch++) { \
dest += (std::pow(fabs((float)source[indexPixel_up + ch] - \
source[indexPixel + ch]), \
2) + \
\
std::pow(fabs((float)source[indexPixel_down + ch] - \
source[indexPixel + ch]), \
2) + \
\
std::pow(fabs((float)source[indexPixel_left + ch] - \
source[indexPixel + ch]), \
2) + \
std::pow(fabs((float)source[indexPixel_right + ch] - \
source[indexPixel + ch]), \
2)); \
} \
} else if (function == "gradhoriz") { \
/* take the gradient along the horizontal only*/ \
for (auto ch = 0; ch < (nbColorChannels); ch++) { \
dest += ((fabs((float)source[indexPixel_left + ch] - \
source[indexPixel + ch])) + \
(fabs((float)source[indexPixel_right + ch] - \
source[indexPixel + ch]))); \
} \
} else if (function == "gradvertic") { \
/* take the gradient along the vertical only*/ \
for (auto ch = 0; ch < (nbColorChannels); ch++) { \
dest += ((fabs((float)source[indexPixel_up + ch] - \
source[indexPixel + ch])) + \
(fabs((float)source[indexPixel_down + ch] - \
source[indexPixel + ch]))); \
} \
} else if (function == "gradnorminf") { \
for (auto ch = 0; ch < (nbColorChannels); ch++) { \
dest += std::max(std::max((fabs((float)source[indexPixel_up + ch] - \
source[indexPixel + ch])), \
\
(fabs((float)source[indexPixel_down + ch] - \
source[indexPixel + ch]))), \
std::max( \
\
(fabs((float)source[indexPixel_left + ch] - \
source[indexPixel + ch])), \
(fabs((float)source[indexPixel_right + ch] - \
source[indexPixel + ch])))); \
} \
} else if (function == "sumexpgradcomp") { \
\
for (auto ch = 0; ch < (nbColorChannels); ch++) { \
dest += (std::exp(fabs((float)source[indexPixel_up + ch] - \
source[indexPixel + ch]) / \
255) + \
\
std::exp(fabs((float)source[indexPixel_down + ch] - \
source[indexPixel + ch]) / \
255) + \
\
std::exp(fabs((float)source[indexPixel_left + ch] - \
source[indexPixel + ch]) / \
255) + \
std::exp(fabs((float)source[indexPixel_right + ch] - \
source[indexPixel + ch]) / \
255)); \
} \
} else { \
std::cerr << "no implementation found for function \"" << function << "\"" \
<< std::endl; \
exit(1); \
}}
// Le alpha n'est pas pris en compte dans l'énergie
// Here, we use this /ugly/ macro to avoid defining a function that would be way
// slower...
/** e_1 energy*/
std::vector<float> energy_e1(std::vector<unsigned char> source, int width,
int height, int nbChannels) {
int nbColorChannels =
nbChannels > 3 ? 3 : nbChannels; // nombre de canaux, excepté le alpha
std::vector<float> energy(width * height);
float max_energy = 0;
for (auto i = 0; i < width; i++) {
for (auto j = 0; j < height; j++) {
compute_energy_for_pixel(source, width, height, i, j, nbChannels,
nbColorChannels, energy[width * j + i]);
}
}
return energy;
}
/** Given the energy value, returns the optimal seam */
template <typename T>
std::vector<int> optimal_seam(std::vector<T> energy, int width, int height,
bool vertical) {
// dyn_energy is indexed by [dim_large*(i : dim_long) + (j : dim_large)]
std::vector<T> dyn_energy(width * height);
int dim_large = vertical ? width : height;
int dim_long = vertical ? height : width; // Number of elements in the seam
//* Find an end of the minimal connected vertical/horizontal seam
for (auto i = 0; i < dim_large; i++) {
dyn_energy[i] = energy[vertical ? i : i*width];
}
for (auto i = 1; i < dim_long; i++) { // Propagate dyn_energy
for (auto j = 0; j < dim_large; j++) {
dyn_energy[dim_large * i + j] = limits::max_energy();
int lower_bound = std::max(j - max_step, 0);
int upper_bound = std::min(j + max_step, dim_large - 1);
// Compute energy based on predecessors
for (auto k = lower_bound; k <= upper_bound; k++) {
if (dyn_energy[dim_large * (i - 1) + k] <
dyn_energy[dim_large * i + j]) {
dyn_energy[dim_large * i + j] = dyn_energy[dim_large * (i - 1) + k];
}
}
dyn_energy[dim_large * i + j] += energy[im_index(i, j)];
}
}
std::vector<int> result(dim_long);
// Find the seam end
int min_idx = -1;
T min_val = limits::max_energy();
for (auto j = 0; j < dim_large; j++) {
if (dyn_energy[dim_large * (dim_long - 1) + j] < min_val) {
min_idx = j;
min_val = dyn_energy[dim_large * (dim_long - 1) + j];
}
}
result[dim_long - 1] = min_idx;
//* Backtracking to find the path
for (auto i = dim_long - 1; i > 0; i--) {
// We want to find either (bot_l, bot_c, bot_r) with dyn_energy[.] = min_val -
// energy[cur]
// Idea : float next_energy = min_val - energy[width*i + min_idx];
//! With floats, we don't always have x + y - y == x, so we check is x+y == x+y
// This define is a bit ugly but 200x faster than using a lambda function
#define is_next_idx(idx) \
(dyn_energy[(i - 1) * dim_large + idx] + energy[im_index(i, min_idx)] == \
min_val)
// This is not the nicest way to do this but we want to check in priority
// at the center to have straight seams
bool found = false;
if (is_next_idx(min_idx)) {
min_val = dyn_energy[(i - 1) * dim_large + min_idx];
found = true;
}
for (auto k = 1; !found && k <= max_step; k++) {
if (min_idx + k < dim_large && is_next_idx(min_idx + k)) {
min_val = dyn_energy[(i - 1) * dim_large + min_idx + k];
min_idx = min_idx + k;
found = true;
} else if (min_idx - k >= 0 && is_next_idx(min_idx - k)) {
min_val = dyn_energy[(i - 1) * dim_large + min_idx - k];
min_idx = min_idx - k;
found = true;
}
}
if (!found) {
std::cerr << "Unable to backtrack path !" << std::endl;
exit(1);
}
result[i - 1] = min_idx;
}
return result;
}
/** Carves an image by one seam. Returns the optimal seam used */
template <typename T>
void remove_seam(const std::vector<T> source, std::vector<T> &output, int width,
int height, int nbChannels, bool vertical,
const std::vector<int> seam) {
// remove the given seam from the image, the result is in output
// the output must have at least the right size!
int dim_large = vertical ? width : height;
int dim_long = vertical ? height : width;
for (auto i = 0; i < dim_long; i++) {
int cur_j = 0;
for (auto j = 0; cur_j < dim_large - 1 && j < dim_large; j++) {
if (seam[i] != j) {
int out_pixelIndex = nbChannels * (vertical ? ((width - 1) * i + cur_j)
: (width * cur_j + i));
int src_pixelIndex = nbChannels * im_index(i, j);
for (auto ch = 0; ch < nbChannels; ch++)
output[out_pixelIndex + ch] = source[src_pixelIndex + ch];
cur_j++;
}
}
}
}
// It would be preferable to use templates only for the value assignation but
// this is in fact far less efficient
void recompute_energy_along_seam(std::vector<unsigned char> carved_img,
std::vector<float> &output_energy,
std::vector<int> opt_seam, int width,
int height, int nbChannels,
int nbColorChannels, bool vertical) {
int dim_large = vertical ? width : height;
int dim_long = vertical ? height : width;
int newWidth = vertical ? width - 1 : width;
int newHeight = vertical ? height : height - 1;
for (auto j0 = 0; j0 < dim_long; j0++) {
auto i0 = opt_seam[j0];
for (auto i_offset = -max_step - 1; i_offset <= max_step + 1; i_offset++) {
for (auto j_offset = -max_step - 1; j_offset <= max_step + 1;
j_offset++) {
int x = vertical ? (i0 + i_offset) : j0 + j_offset;
int y = vertical ? j0 + j_offset : (i0 + i_offset);
if (((0 <= (i0 + i_offset)) && ((i0 + i_offset) < dim_large - 1)) &&
(((0 <= j0 + j_offset) && (j0 + j_offset < dim_long)))) {
compute_energy_for_pixel(carved_img, newWidth, newHeight, x, y,
nbChannels, nbColorChannels,
output_energy[width * y + x]);
}
}
}
}
}
void recompute_energy_along_seam(
std::vector<unsigned char> carved_img,
std::vector<std::pair<int, float>> &output_energy,
std::vector<int> opt_seam, int width, int height, int nbChannels,
int nbColorChannels, bool vertical) {
int dim_large = vertical ? width : height;
int dim_long = vertical ? height : width;
int newWidth = vertical ? width - 1 : width;
int newHeight = vertical ? height : height - 1;
for (auto j0 = 0; j0 < dim_long; j0++) {
auto i0 = opt_seam[j0];
for (auto i_offset = -max_step - 1; i_offset <= max_step + 1; i_offset++) {
for (auto j_offset = -max_step - 1; j_offset <= max_step + 1;
j_offset++) {
int x = vertical ? (i0 + i_offset) : j0 + j_offset;
int y = vertical ? j0 + j_offset : (i0 + i_offset);
if (((0 < (i0 + i_offset)) && ((i0 + i_offset) < dim_large - 1)) &&
(((0 < j0 + j_offset) && (j0 + j_offset < dim_long)))) {
// if the pixel is to be removed, we keep the energy at 0.
if (output_energy[width * y + x].first != 0)
compute_energy_for_pixel(carved_img, newWidth, newHeight, x, y,
nbChannels, nbColorChannels,
output_energy[width * y + x].second);
}
}
}
}
}
/** Carves an image and its energy by one seam, and recomputes the energy.
Returns the optimal seam used */
template <typename T>
std::vector<int> carving_step(const std::vector<unsigned char> source_img,
std::vector<T> source_energy,
std::vector<unsigned char> &output_img,
std::vector<T> &output_energy, int width,
int height, int nbChannels, int nbColorChannels,
bool vertical) {
std::vector<int> opt_seam =
optimal_seam(source_energy, width, height, vertical);
remove_seam(source_img, output_img, width, height, nbChannels, vertical,
opt_seam);
remove_seam(source_energy, output_energy, width, height, 1, vertical,
opt_seam);
// Recompute the energy along the seam, we need a separate function for
// templating
recompute_energy_along_seam(source_img, output_energy, opt_seam, width,
height, nbChannels, nbColorChannels, vertical);
return opt_seam;
}
auto seam_carving(unsigned char *source, int width, int height, int nbChannels,
int nbSeams, bool vertical, unsigned char *mask = nullptr) {
int nbColorChannels = nbChannels > 3 ? 3 : nbChannels;
int curWidth = width;
int curHeight = height;
int dim_large = vertical ? width : height;
int dim_long = vertical ? height : width;
// dim_long=longueur des seam
std::vector<unsigned char> source_img(width * height * nbChannels);
// Contains at each step the carved image
std::vector<float> source_energy(width * height);
// Contains at each step the carved energy
std::vector<std::pair<int, float>> masked_energy;
std::vector<std::pair<int, float>> output_masked_energy(width * height);
// Source energy with (-1, 0, 1) on first element according to mask value
std::vector<unsigned char> output_img(width * height * nbChannels);
// Receives at each step the newly carved image
std::vector<float> output_energy(width * height);
// Contains at each step the carved energy
std::vector<bool> complete_blacklist(width * height);
// Contains all removed pixels, for "test_energy"
std::vector<float> ini_energy;
// Contains the initial energy, only for "test_energy"
std::vector<unsigned char> test_energy_output(width * height * nbChannels);
// Final output for "test_energy"
for (auto i = 0; i < width * height * nbChannels; i++) {
source_img[i] = source[i];
}
source_energy = energy_e1(source_img, width, height, nbChannels);
if (mask)
masked_energy = mask_energy(source_energy, width, height, mask);
if (show_seams) {
ini_energy = energy_e1(source_img, width, height, nbChannels);
for (auto k = 0; k < width * height; k++) {
complete_blacklist[k] = false;
}
//* Prepare final output
float max_energy = __FLT_MIN__;
for (auto k = 0; k < width * height; k++) {
max_energy = std::max(max_energy, ini_energy[k]);
}
if (max_energy != 0) {
for (auto k = 0; k < width * height; k++) {
ini_energy[k] /= max_energy;
}
}
for (auto k = 0; k < width * height; k++) {
//* Uncomment if you prefer to see darkened source image
// for (auto i=0; i < nbColorChannels; i++)
// output[nbChannels*k+i] = source_img[nbChannels*k+i]/nbChannels;
for (auto ch = 0; ch < nbColorChannels; ch++) {
test_energy_output[nbChannels * k + ch] = ini_energy[k] * 255;
}
if (nbChannels == 4)
test_energy_output[nbChannels * k + 3] = source_img[nbChannels * k + 3];
if (mask) {
if (mask[k] == 2) // Green
test_energy_output[nbChannels * k + 1] = 125;
else if (mask[k] == 0) { // Red
test_energy_output[nbChannels * k] = 125;
}
}
}
}
SimpleProgressBar::ProgressBar bar(until_mask_removal ? dim_large : nbSeams);
bar.print();
auto seam_index = 0;
while (seam_index++ < nbSeams || until_mask_removal) {
std::vector<int> opt_seam;
if (mask) {
opt_seam = carving_step(source_img, masked_energy, output_img,
output_masked_energy, curWidth, curHeight,
nbChannels, nbColorChannels, vertical);
if (until_mask_removal &&
!does_seam_remove_mask(masked_energy, curWidth, curHeight, nbChannels, opt_seam,
vertical))
break;
} else {
opt_seam = carving_step(source_img, source_energy, output_img,
output_energy, curWidth, curHeight, nbChannels,
nbColorChannels, vertical);
}
std::copy(output_img.begin(), output_img.end(), source_img.begin());
std::copy(output_energy.begin(), output_energy.end(),
source_energy.begin());
if (mask)
std::copy(output_masked_energy.begin(), output_masked_energy.end(),
masked_energy.begin());
vertical ? curWidth-- : curHeight--; // We just reduced the dimension
if (show_seams) { // Update blacklist
for (auto i = 0; i < dim_long; i++) {
int j, cur_j = 0; // cur_j is the index relative to the current carved
// image. j is absolute in the source image
for (j = 0; j < dim_large &&
(cur_j < opt_seam[i] || complete_blacklist[im_index(i, j)]);
j++) {
if (!complete_blacklist[im_index(i, j)]) {
cur_j++;
}
}
assert(cur_j == opt_seam[i]); // Else, j == width and cur_j is not in
// the source image..
complete_blacklist[im_index(i, j)] = true;
test_energy_output[nbChannels * im_index(i, j)] =
255; // Set carved pixel to red
}
}
bar.increment();
bar.print();
}
std::cout << std::endl; // Add newline after ProgressBar
if (show_seams) {
return std::make_tuple(test_energy_output, width, height, nbChannels);
} else {
return std::make_tuple(source_img, curWidth, curHeight, nbChannels);
}
}
int main(int argc, char **argv) {
CLI::App app{"seam-carving"};
std::string maskImage;
std::string sourceImage;
std::string outputImage = "output.png";
int nbSeams = DEFAULT_SEAMS;
bool vertical = false;
app.add_option("-s,--source", sourceImage, "Source image")
->required()
->check(CLI::ExistingFile);
app.add_option("-o,--output", outputImage, "Output image")->required();
app.add_option("-m,--mask", maskImage, "Source image")
->check(CLI::ExistingFile);
app.add_option("-n,--nb-seams", nbSeams, "Number of seams")
->check(CLI::Number);
app.add_option("--max-step", max_step, "Max width of step to find a seam")
->check(CLI::Number);
app.add_flag("--vertical", vertical,
"Vertical carving (remove vertical seams)");
app.add_flag("--silent", silent, "No verbose messages");
app.add_flag("--show-seams", show_seams,
"Don't resize image, just try the specified energy function");
app.add_option("-f,--function", function,
"The function to apply to compute the energy (default: gradient)");
app.add_flag(
"-u,--until-mask-removal", until_mask_removal,
"Carve the image until there are no more red pixels in the mask");
CLI11_PARSE(app, argc, argv);
// Image loading
int width, height, nbChannels;
unsigned char *source =
stbi_load(sourceImage.c_str(), &width, &height, &nbChannels, 0);
unsigned char *mask = nullptr;
if (!maskImage.empty()) {
int maskWidth, maskHeight, maskChannels;
mask =
stbi_load(maskImage.c_str(), &maskWidth, &maskHeight, &maskChannels, 0);
if (maskWidth != width || maskHeight != height) {
std::cerr << maskImage << " and " << sourceImage
<< " differ in dimension. Please provide a valid mask."
<< std::endl;
exit(1);
}
if (maskChannels < 3) {
std::cerr << maskImage << " needs to be RGB." << std::endl;
exit(1);
}
unsigned char r, g, b;
for (auto i = 0; i < width * height; i++) {
r = mask[maskChannels * i];
g = mask[maskChannels * i + 1];
b = mask[maskChannels * i + 2];
bool positive = (g > r && g > b &&
g > 100); // Mask images are not always the cleanest
bool negative = (r > g && r > b && r > 100);
mask[i] = positive ? 2 : (negative ? 0 : 1);
}
//* "mask" has the same dimensions as source and one single channel
//* The values are:
//* . (2) we want to keep the pixel
//* . (1) nothing in particular
//* . (0) we want to remove the pixel
}
if (until_mask_removal && maskImage.empty()) {
std::cerr << "Flag --until-mask-removal but no mask provided." << std::endl;
until_mask_removal = false;
}
if (until_mask_removal && nbSeams != DEFAULT_SEAMS) {
std::cerr << "Flag --nb-seams specified but --until-mask-removal provided."
<< std::endl;
nbSeams = DEFAULT_SEAMS;
}
nbSeams = std::min(
nbSeams,
vertical ? width - 1
: height - 1); // We want to keep at least one row or column
auto result = seam_carving(source, width, height, nbChannels, nbSeams,
vertical, mask = mask);
auto content = std::get<0>(result);
int width_output = std::get<1>(result);
int height_output = std::get<2>(result);
int nbChannels_output = std::get<3>(result);
export_image(outputImage.c_str(), content.data(), width_output, height_output,
nbChannels_output);
stbi_image_free(source);
exit(0);
}