void reduce_4 (T const& in, image_data_8 & out, octree<rgb> trees[], unsigned limits[], unsigned levels, std::vector<unsigned> & alpha)
{
unsigned width = in.width();
unsigned height = in.height();
//unsigned alphaCount[alpha.size()];
std::vector<unsigned> alphaCount(alpha.size());
for(unsigned i=0; i<alpha.size(); i++)
{
alpha[i] = 0;
alphaCount[i] = 0;
}
for (unsigned y = 0; y < height; ++y)
{
mapnik::image_data_32::pixel_type const * row = in.getRow(y);
mapnik::image_data_8::pixel_type * row_out = out.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
mapnik::rgb c(U2RED(val), U2GREEN(val), U2BLUE(val));
byte index = 0;
int idx=-1;
for(int j=levels-1; j>0; j--){
if (U2ALPHA(val)>=limits[j] && trees[j].colors()>0) {
index = idx = trees[j].quantize(c);
break;
}
}
if (idx>=0 && idx<(int)alpha.size())
{
alpha[idx]+=U2ALPHA(val);
alphaCount[idx]++;
}
if (x%2 == 0) index = index<<4;
row_out[x>>1] |= index;
}
}
for(unsigned i=0; i<alpha.size(); i++)
{
if (alphaCount[i]!=0)
alpha[i] /= alphaCount[i];
}
}
void save_as_png8_hex(T1 & file, T2 const& image, int colors = 256,
int compression = Z_DEFAULT_COMPRESSION, int strategy = Z_DEFAULT_STRATEGY,
int trans_mode = -1, double gamma = 2.0)
{
unsigned width = image.width();
unsigned height = image.height();
// structure for color quantization
hextree<mapnik::rgba> tree(colors);
if (trans_mode >= 0)
tree.setTransMode(trans_mode);
if (gamma > 0)
tree.setGamma(gamma);
for (unsigned y = 0; y < height; ++y)
{
typename T2::pixel_type const * row = image.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
tree.insert(mapnik::rgba(U2RED(val), U2GREEN(val), U2BLUE(val), U2ALPHA(val)));
}
}
//transparency values per palette index
std::vector<mapnik::rgba> pal;
tree.create_palette(pal);
assert(int(pal.size()) <= colors);
std::vector<mapnik::rgb> palette;
std::vector<unsigned> alphaTable;
for(unsigned i=0; i<pal.size(); i++)
{
palette.push_back(rgb(pal[i].r, pal[i].g, pal[i].b));
alphaTable.push_back(pal[i].a);
}
save_as_png8<T1, T2, hextree<mapnik::rgba> >(file, image, tree, palette, alphaTable, compression, strategy);
}
void save_as_png8_oct(T1 & file,
T2 const& image,
png_options const& opts)
{
// number of alpha ranges in png8 format; 2 results in smallest image with binary transparency
// 3 is minimum for semitransparency, 4 is recommended, anything else is worse
const unsigned TRANSPARENCY_LEVELS = (opts.trans_mode==2||opts.trans_mode<0)?MAX_OCTREE_LEVELS:2;
unsigned width = image.width();
unsigned height = image.height();
unsigned alphaHist[256];//transparency histogram
unsigned semiCount = 0;//sum of semitransparent pixels
unsigned meanAlpha = 0;
if (opts.trans_mode == 0)
{
meanAlpha = 255;
}
else
{
for(int i=0; i<256; i++)
{
alphaHist[i] = 0;
}
for (unsigned y = 0; y < height; ++y)
{
for (unsigned x = 0; x < width; ++x)
{
unsigned val = U2ALPHA(static_cast<unsigned>(image.get_row(y)[x]));
alphaHist[val]++;
meanAlpha += val;
if (val>0 && val<255)
{
semiCount++;
}
}
}
meanAlpha /= width*height;
}
// transparency ranges division points
unsigned limits[MAX_OCTREE_LEVELS+1];
limits[0] = 0;
limits[1] = (opts.trans_mode!=0 && alphaHist[0]>0)?1:0;
limits[TRANSPARENCY_LEVELS] = 256;
for(unsigned j=2; j<TRANSPARENCY_LEVELS; j++)
{
limits[j] = limits[1];
}
if (opts.trans_mode != 0)
{
unsigned alphaHistSum = 0;
for(unsigned i=1; i<256; i++)
{
alphaHistSum += alphaHist[i];
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
{
if (alphaHistSum<semiCount*(j)/4)
{
limits[j] = i;
}
}
}
}
// avoid too wide full transparent range
if (limits[1]>256/(TRANSPARENCY_LEVELS-1))
{
limits[1]=256/(TRANSPARENCY_LEVELS-1);
}
// avoid too wide full opaque range
if (limits[TRANSPARENCY_LEVELS-1]<212)
{
limits[TRANSPARENCY_LEVELS-1]=212;
}
if (TRANSPARENCY_LEVELS==2)
{
limits[1]=127;
}
// estimated number of colors from palette assigned to chosen ranges
unsigned cols[MAX_OCTREE_LEVELS];
// count colors
if (opts.trans_mode == 0)
{
for (unsigned j=0; j<TRANSPARENCY_LEVELS; j++)
{
cols[j] = 0;
}
cols[TRANSPARENCY_LEVELS-1] = width * height;
}
else
{
for (unsigned j=0; j<TRANSPARENCY_LEVELS; j++)
{
cols[j] = 0;
for (unsigned i=limits[j]; i<limits[j+1]; i++)
{
cols[j] += alphaHist[i];
}
}
}
unsigned divCoef = width*height-cols[0];
if (divCoef==0)
{
divCoef = 1;
}
cols[0] = cols[0]>0?1:0; // fully transparent color (one or not at all)
if (opts.colors>=64)
{
// give chance less populated but not empty cols to have at least few colors(12)
unsigned minCols = (12+1)*divCoef/(opts.colors-cols[0]);
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
{
if (cols[j]>12 && cols[j]<minCols)
{
divCoef += minCols-cols[j];
cols[j] = minCols;
}
}
}
unsigned usedColors = cols[0];
for(unsigned j=1; j<TRANSPARENCY_LEVELS-1; j++)
{
cols[j] = cols[j]*(opts.colors-cols[0])/divCoef;
usedColors += cols[j];
}
// use rest for most opaque group of pixels
cols[TRANSPARENCY_LEVELS-1] = opts.colors-usedColors;
//no transparency
if (opts.trans_mode == 0)
{
limits[1] = 0;
cols[0] = 0;
cols[1] = opts.colors;
}
// octree table for separate alpha range with 1-based index (0 is fully transparent: no color)
octree<rgb> trees[MAX_OCTREE_LEVELS];
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
{
trees[j].setMaxColors(cols[j]);
}
for (unsigned y = 0; y < height; ++y)
{
typename T2::pixel_type const * row = image.get_row(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
// insert to proper tree based on alpha range
for(unsigned j=TRANSPARENCY_LEVELS-1; j>0; j--)
{
if (cols[j]>0 && U2ALPHA(val)>=limits[j])
{
trees[j].insert(mapnik::rgb(U2RED(val), U2GREEN(val), U2BLUE(val)));
break;
}
}
}
}
unsigned leftovers = 0;
std::vector<rgb> palette;
palette.reserve(opts.colors);
if (cols[0])
{
palette.push_back(rgb(0,0,0));
}
for(unsigned j=1; j<TRANSPARENCY_LEVELS; j++)
{
if (cols[j]>0)
{
if (leftovers>0)
{
cols[j] += leftovers;
trees[j].setMaxColors(cols[j]);
leftovers = 0;
}
std::vector<rgb> pal;
trees[j].setOffset( static_cast<unsigned>(palette.size()));
trees[j].create_palette(pal);
leftovers = cols[j] - static_cast<unsigned>(pal.size());
cols[j] = static_cast<unsigned>(pal.size());
palette.insert(palette.end(), pal.begin(), pal.end());
}
}
//transparency values per palette index
std::vector<unsigned> alphaTable;
//alphaTable.resize(palette.size());//allow semitransparency also in almost opaque range
if (opts.trans_mode != 0)
{
alphaTable.resize(palette.size() - cols[TRANSPARENCY_LEVELS-1]);
}
if (palette.size() > 16 )
{
// >16 && <=256 colors -> write 8-bit color depth
image_gray8 reduced_image(width,height);
reduce_8(image, reduced_image, trees, limits, TRANSPARENCY_LEVELS, alphaTable);
save_as_png(file,palette,reduced_image,width,height,8,alphaTable,opts);
}
else if (palette.size() == 1)
{
// 1 color image -> write 1-bit color depth PNG
unsigned image_width = ((width + 15) >> 3) & ~1U; // 1-bit image, round up to 16-bit boundary
unsigned image_height = height;
image_gray8 reduced_image(image_width,image_height);
reduce_1(image,reduced_image,trees, limits, alphaTable);
if (meanAlpha<255 && cols[0]==0)
{
alphaTable.resize(1);
alphaTable[0] = meanAlpha;
}
save_as_png(file,palette,reduced_image,width,height,1,alphaTable,opts);
}
void save_as_png256_hex(T1 & file, T2 const& image, int colors = 256, int trans_mode = -1, double gamma = 2.0)
{
unsigned width = image.width();
unsigned height = image.height();
// structure for color quantization
hextree<mapnik::rgba> tree(colors);
if (trans_mode >= 0)
tree.setTransMode(trans_mode);
if (gamma > 0)
tree.setGamma(gamma);
for (unsigned y = 0; y < height; ++y)
{
typename T2::pixel_type const * row = image.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
tree.insert(mapnik::rgba(U2RED(val), U2GREEN(val), U2BLUE(val), U2ALPHA(val)));
}
}
//transparency values per palette index
std::vector<mapnik::rgba> pal;
tree.create_palette(pal);
assert(int(pal.size()) <= colors);
std::vector<mapnik::rgb> palette;
std::vector<unsigned> alphaTable;
for(unsigned i=0; i<pal.size(); i++)
{
palette.push_back(rgb(pal[i].r, pal[i].g, pal[i].b));
alphaTable.push_back(pal[i].a);
}
if (palette.size() > 16 )
{
// >16 && <=256 colors -> write 8-bit color depth
image_data_8 reduced_image(width, height);
for (unsigned y = 0; y < height; ++y)
{
mapnik::image_data_32::pixel_type const * row = image.getRow(y);
mapnik::image_data_8::pixel_type * row_out = reduced_image.getRow(y);
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
mapnik::rgba c(U2RED(val), U2GREEN(val), U2BLUE(val), U2ALPHA(val));
row_out[x] = tree.quantize(c);
}
}
save_as_png(file, palette, reduced_image, width, height, 8, alphaTable);
}
else if (palette.size() == 1)
{
// 1 color image -> write 1-bit color depth PNG
unsigned image_width = (int(0.125*width) + 7)&~7;
unsigned image_height = height;
image_data_8 reduced_image(image_width, image_height);
reduced_image.set(0);
save_as_png(file, palette, reduced_image, width, height, 1, alphaTable);
}
else
{
// <=16 colors -> write 4-bit color depth PNG
unsigned image_width = (int(0.5*width) + 3)&~3;
unsigned image_height = height;
image_data_8 reduced_image(image_width, image_height);
for (unsigned y = 0; y < height; ++y)
{
mapnik::image_data_32::pixel_type const * row = image.getRow(y);
mapnik::image_data_8::pixel_type * row_out = reduced_image.getRow(y);
byte index = 0;
for (unsigned x = 0; x < width; ++x)
{
unsigned val = row[x];
mapnik::rgba c(U2RED(val), U2GREEN(val), U2BLUE(val), U2ALPHA(val));
index = tree.quantize(c);
if (x%2 == 0) index = index<<4;
row_out[x>>1] |= index;
}
}
save_as_png(file, palette, reduced_image, width, height, 4, alphaTable);
}
}