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Quantize already indexed images more efficiently

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Kovid Goyal 2016-05-09 14:35:49 +05:30
parent 8f5c29268f
commit ad9c0ff5ff
1 changed files with 51 additions and 21 deletions
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72
src/calibre/utils/imageops/quantize.cpp
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@ -18,6 +18,9 @@
#include <QVector>
#include "imageops.h"
// Increasing this number improves quality but also increases running time and memory consumption
static const size_t MAX_LEAVES = 2000;
#ifdef _MSC_VER
typedef unsigned __int64 uint64_t;
typedef __int64 int64_t;
@ -107,6 +110,8 @@ public:
if (this->avg.red != 0) throw std::runtime_error("Compiler failed to default initialize avg");
}
// Adding colors to the tree {{{
inline Node* create_child(const size_t level, const size_t depth, unsigned int *leaf_count, Node **reducible_nodes, Pool<Node> &node_pool) {
Node *c = node_pool.checkout();
if (level == depth) {
@ -141,7 +146,10 @@ public:
this->children[index]->add_color(r, g, b, depth, level + 1, leaf_count, reducible_nodes, node_pool);
}
}
// }}}
// Tree reduction {{{
inline uint64_t total_error() const {
Node *child = NULL;
uint64_t ans = 0;
@ -239,8 +247,10 @@ public:
}
}
}
// }}}
void set_palette_colors(QRgb *color_table, unsigned char *index, bool compute_parent_averages) {
void set_palette_colors(QRgb *color_table, unsigned char *index, bool compute_parent_averages) { // {{{
/* Create the color palette based on all existing leaf nodes. */
int i;
Node *child;
if (this->is_leaf) {
@ -261,9 +271,10 @@ public:
}
if (compute_parent_averages) this->update_average();
}
}
} // }}}
unsigned char index_for_nearest_color(const uint32_t r, const uint32_t g, const uint32_t b, const size_t level) {
unsigned char index_for_nearest_color(const uint32_t r, const uint32_t g, const uint32_t b, const size_t level) { // {{{
/* Returns the color palette index for the nearest color to (r, g, b) */
if (this->is_leaf) return this->index;
size_t index = get_index(r, g, b, level);
if (this->children[index] == NULL) {
@ -277,7 +288,7 @@ public:
}
}
return this->children[index]->index_for_nearest_color(r, g, b, level + 1);
}
} // }}}
};
@ -335,6 +346,33 @@ static void dither_image(const QImage &img, QImage &ans, QVector<QRgb> &color_ta
}
// }}}
inline unsigned int read_colors(const QImage &img, Node &root, size_t depth, Node **reducible_nodes, Pool<Node> &node_pool) {
int iwidth = img.width(), iheight = img.height(), r, c;
unsigned int leaf_count = 0;
const QRgb* line = NULL;
for (r = 0; r < iheight; r++) {
line = reinterpret_cast<const QRgb*>(img.constScanLine(r));
for (c = 0; c < iwidth; c++) {
const QRgb pixel = *(line + c);
root.add_color(qRed(pixel), qGreen(pixel), qBlue(pixel), depth, 0, &leaf_count, reducible_nodes, node_pool);
while (leaf_count > MAX_LEAVES)
root.reduce(depth, &leaf_count, reducible_nodes, node_pool);
}
}
return leaf_count;
}
inline unsigned int read_colors(const QVector<QRgb> &color_table, Node &root, size_t depth, Node **reducible_nodes, Pool<Node> &node_pool) {
unsigned int leaf_count = 0;
for (int i = 0; i < color_table.size(); i++) {
const QRgb pixel = color_table.at(i);
root.add_color(qRed(pixel), qGreen(pixel), qBlue(pixel), depth, 0, &leaf_count, reducible_nodes, node_pool);
while (leaf_count > MAX_LEAVES)
root.reduce(depth, &leaf_count, reducible_nodes, node_pool);
}
return leaf_count;
}
QImage quantize(const QImage &image, unsigned int maximum_colors, bool dither) {
ScopedGILRelease PyGILRelease;
size_t depth = 0;
@ -345,34 +383,26 @@ QImage quantize(const QImage &image, unsigned int maximum_colors, bool dither) {
Node* reducible_nodes[MAX_DEPTH + 1] = {0};
Node root = Node();
QVector<QRgb> color_table = QVector<QRgb>(MAX_COLORS);
const QRgb* line = NULL;
// Increasing this number improves quality but also increases running time and memory consumption
static const size_t MAX_LEAVES = 2000;
QImage::Format fmt = img.format();
root.check_compiler();
maximum_colors = MAX(2, MIN(MAX_COLORS, maximum_colors));
if (img.colorCount() > 0 && (size_t)img.colorCount() <= maximum_colors) return img; // Image is already quantized
if (img.hasAlphaChannel()) throw std::out_of_range("Cannot quantize image with transparency");
// TODO: Handle indexed image with colors > maximum_colors more efficiently
// by iterating over the color table rather than the pixels
if (img.format() != QImage::Format_RGB32) img = img.convertToFormat(QImage::Format_RGB32);
if (img.isNull()) throw std::bad_alloc();
if (fmt != QImage::Format_RGB32 && fmt != QImage::Format_Indexed8 && fmt != 24) { // 24 = QImage::Format_Grayscale8
img = img.convertToFormat(QImage::Format_RGB32);
if (img.isNull()) throw std::bad_alloc();
}
// There can be no more than MAX_LEAVES * 8 nodes. Add 1 in case there is an off by 1 error somewhere.
Pool<Node> node_pool((MAX_LEAVES + 1) * 8);
depth = (size_t)log2(maximum_colors);
depth = MAX(2, MIN(depth, MAX_DEPTH));
for (r = 0; r < iheight; r++) {
line = reinterpret_cast<const QRgb*>(img.constScanLine(r));
for (c = 0; c < iwidth; c++) {
const QRgb pixel = *(line + c);
root.add_color(qRed(pixel), qGreen(pixel), qBlue(pixel), depth, 0, &leaf_count, reducible_nodes, node_pool);
while (leaf_count > MAX_LEAVES)
root.reduce(depth, &leaf_count, reducible_nodes, node_pool);
}
}
if (img.format() == QImage::Format_RGB32) leaf_count = read_colors(img, root, depth, reducible_nodes, node_pool);
else leaf_count = read_colors(img.colorTable(), root, depth, reducible_nodes, node_pool);
while (leaf_count > maximum_colors + 7)
root.reduce(depth, &leaf_count, reducible_nodes, node_pool);
if (leaf_count > maximum_colors) {
@ -388,7 +418,7 @@ QImage quantize(const QImage &image, unsigned int maximum_colors, bool dither) {
dither_image(img, ans, color_table, root);
} else {
for (r = 0; r < iheight; r++) {
line = reinterpret_cast<const QRgb*>(img.constScanLine(r));
const QRgb *line = reinterpret_cast<const QRgb*>(img.constScanLine(r));
bits = ans.scanLine(r);
for (c = 0; c < iwidth; c++) {
const QRgb pixel = *(line + c);