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Ensure that exactly the specified number of colors is produced

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This commit is contained in:
Kovid Goyal 2016-05-09 14:09:38 +05:30
parent 4f307ddae1
commit 8f5c29268f
1 changed files with 63 additions and 19 deletions
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82
src/calibre/utils/imageops/quantize.cpp
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@ -162,9 +162,26 @@ public:
return ans;
}
inline unsigned int merge(Pool<Node> &node_pool) {
unsigned int num = 0, i;
Node *child = NULL;
for (i = 0; i < MAX_DEPTH; i++) {
if ((child = this->children[i]) != NULL) {
iadd<SumPixel>(this->sum, child->sum);
iadd<SumPixel>(this->error_sum, child->error_sum);
this->pixel_count += this->children[i]->pixel_count;
node_pool.relinquish(this->children[i]); this->children[i] = NULL;
num ++;
}
}
this->update_average();
this->is_leaf = true;
return num;
}
void reduce(const size_t depth, unsigned int *leaf_count, Node **reducible_nodes, Pool<Node> &node_pool) {
size_t i = 0;
Node *node = NULL, *child = NULL, *q = NULL;
Node *node = NULL, *q = NULL;
// Find the deepest level containing at least one reducible node
for (i=depth - 1; i > 0 && reducible_nodes[i] == NULL; i--);
@ -179,18 +196,48 @@ public:
q = q->next_reducible_node;
}
}
*leaf_count -= node->merge(node_pool) - 1;
}
for (i = 0; i < MAX_DEPTH; i++) {
if ((child = node->children[i]) != NULL) {
iadd<SumPixel>(node->sum, child->sum);
iadd<SumPixel>(node->error_sum, child->error_sum);
node->pixel_count += node->children[i]->pixel_count;
node_pool.relinquish(node->children[i]); node->children[i] = NULL;
(*leaf_count)--;
void find_least_used_leaf(uint64_t *pixel_count, Node **ans, Node **parent) {
if (this->is_leaf) {
if (this->pixel_count < *pixel_count) { *pixel_count = this->pixel_count; *ans = this; }
} else {
Node *child = NULL;
for (int i = 0; i < MAX_DEPTH; i++) {
if ((child = this->children[i]) != NULL) {
child->find_least_used_leaf(pixel_count, ans, parent);
if (*ans == child) *parent = this;
}
}
}
}
inline unsigned int number_of_children() {
unsigned int ans = 0;
for(int i = 0; i < MAX_DEPTH; i++) {
if (this->children[i] != NULL) ans++;
}
return ans;
}
void reduce_least_common_leaves(const unsigned int num, Pool<Node> &node_pool) {
unsigned int left = num;
Node *leaf = NULL, *parent = NULL;
uint64_t pixel_count = UINT64_MAX;
while (left > 0) {
leaf = NULL; parent = NULL; pixel_count = UINT64_MAX;
this->find_least_used_leaf(&pixel_count, &leaf, &parent);
if (parent->number_of_children() == 1) {
parent->merge(node_pool);
} else {
for(int i = 0; i < MAX_DEPTH; i++) {
if (parent->children[i] == leaf) { node_pool.relinquish(leaf); parent->children[i] = NULL; break; }
}
left--;
}
}
node->update_average();
node->is_leaf = true; *leaf_count += 1;
}
void set_palette_colors(QRgb *color_table, unsigned char *index, bool compute_parent_averages) {
@ -216,13 +263,6 @@ public:
}
}
unsigned char index_for_color(const uint32_t r, const uint32_t g, const uint32_t b, const size_t level) const {
if (this->is_leaf) return this->index;
size_t index = get_index(r, g, b, level);
if (this->children[index] == NULL) throw std::out_of_range("Something bad happened: could not follow tree for color");
return this->children[index]->index_for_color(r, g, b, level + 1);
}
unsigned char index_for_nearest_color(const uint32_t r, const uint32_t g, const uint32_t b, const size_t level) {
if (this->is_leaf) return this->index;
size_t index = get_index(r, g, b, level);
@ -333,8 +373,12 @@ QImage quantize(const QImage &image, unsigned int maximum_colors, bool dither) {
root.reduce(depth, &leaf_count, reducible_nodes, node_pool);
}
}
while (leaf_count > maximum_colors)
while (leaf_count > maximum_colors + 7)
root.reduce(depth, &leaf_count, reducible_nodes, node_pool);
if (leaf_count > maximum_colors) {
root.reduce_least_common_leaves(leaf_count - maximum_colors, node_pool);
leaf_count = maximum_colors;
}
color_table.resize(leaf_count);
root.set_palette_colors(color_table.data(), &index, dither);
@ -348,7 +392,7 @@ QImage quantize(const QImage &image, unsigned int maximum_colors, bool dither) {
bits = ans.scanLine(r);
for (c = 0; c < iwidth; c++) {
const QRgb pixel = *(line + c);
*(bits + c) = root.index_for_color(qRed(pixel), qGreen(pixel), qBlue(pixel), 0);
*(bits + c) = root.index_for_nearest_color(qRed(pixel), qGreen(pixel), qBlue(pixel), 0);
}
}
}