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astrawastraw
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read 12 bit PNGs (patch from Tobias Wood)
svn path=/branches/v0_98_5_maint/; revision=7028
1 parent e2c86e4 commit bde58aa

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‎src/_png.cpp

Lines changed: 46 additions & 48 deletions
Original file line numberDiff line numberDiff line change
@@ -208,38 +208,37 @@ _png_module::read_png(const Py::Tuple& args) {
208208

209209
png_init_io(png_ptr, fp);
210210
png_set_sig_bytes(png_ptr, 8);
211-
212211
png_read_info(png_ptr, info_ptr);
213212

214213
png_uint_32 width = info_ptr->width;
215214
png_uint_32 height = info_ptr->height;
216-
bool do_gray_conversion = (info_ptr->bit_depth < 8 &&
217-
info_ptr->color_type == PNG_COLOR_TYPE_GRAY);
218215

219216
int bit_depth = info_ptr->bit_depth;
220-
if (bit_depth == 16) {
221-
png_set_strip_16(png_ptr);
222-
} else if (bit_depth < 8) {
217+
218+
// Unpack 1, 2, and 4-bit images
219+
if (bit_depth < 8)
223220
png_set_packing(png_ptr);
224-
}
225221

226-
// convert misc color types to rgb for simplicity
227-
if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY ||
228-
info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
229-
png_set_gray_to_rgb(png_ptr);
230-
} else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) {
222+
// If sig bits are set, shift data
223+
png_color_8p sig_bit;
224+
if ((info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) && png_get_sBIT(png_ptr, info_ptr, &sig_bit))
225+
png_set_shift(png_ptr, sig_bit);
226+
227+
// Convert big endian to little
228+
if (bit_depth == 16)
229+
png_set_swap(png_ptr);
230+
231+
// Convert palletes to full RGB
232+
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
231233
png_set_palette_to_rgb(png_ptr);
232-
}
234+
235+
// If there's an alpha channel convert gray to RGB
236+
if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
237+
png_set_gray_to_rgb(png_ptr);
233238

234239
png_set_interlace_handling(png_ptr);
235240
png_read_update_info(png_ptr, info_ptr);
236241

237-
bool rgba = info_ptr->color_type == PNG_COLOR_TYPE_RGBA;
238-
if ( (info_ptr->color_type != PNG_COLOR_TYPE_RGB) && !rgba) {
239-
std::cerr << "Found color type " << (int)info_ptr->color_type << std::endl;
240-
throw Py::RuntimeError("_image_module::readpng: cannot handle color_type");
241-
}
242-
243242
/* read file */
244243
if (setjmp(png_jmpbuf(png_ptr)))
245244
throw Py::RuntimeError("_image_module::readpng: error during read_image");
@@ -255,37 +254,36 @@ _png_module::read_png(const Py::Tuple& args) {
255254
npy_intp dimensions[3];
256255
dimensions[0] = height; //numrows
257256
dimensions[1] = width; //numcols
258-
dimensions[2] = 4;
259-
260-
PyArrayObject *A = (PyArrayObject *) PyArray_SimpleNew(3, dimensions, PyArray_FLOAT);
261-
262-
if (do_gray_conversion) {
263-
float max_value = (float)((1L << bit_depth) - 1);
264-
for (png_uint_32 y = 0; y < height; y++) {
265-
png_byte* row = row_pointers[y];
266-
for (png_uint_32 x = 0; x < width; x++) {
267-
float value = row[x] / max_value;
268-
size_t offset = y*A->strides[0] + x*A->strides[1];
269-
*(float*)(A->data + offset + 0*A->strides[2]) = value;
270-
*(float*)(A->data + offset + 1*A->strides[2]) = value;
271-
*(float*)(A->data + offset + 2*A->strides[2]) = value;
272-
*(float*)(A->data + offset + 3*A->strides[2]) = 1.0f;
273-
}
274-
}
275-
} else {
276-
for (png_uint_32 y = 0; y < height; y++) {
277-
png_byte* row = row_pointers[y];
278-
for (png_uint_32 x = 0; x < width; x++) {
279-
png_byte* ptr = (rgba) ? &(row[x*4]) : &(row[x*3]);
280-
size_t offset = y*A->strides[0] + x*A->strides[1];
281-
*(float*)(A->data + offset + 0*A->strides[2]) = (float)(ptr[0]/255.0);
282-
*(float*)(A->data + offset + 1*A->strides[2]) = (float)(ptr[1]/255.0);
283-
*(float*)(A->data + offset + 2*A->strides[2]) = (float)(ptr[2]/255.0);
284-
*(float*)(A->data + offset + 3*A->strides[2]) = rgba ? (float)(ptr[3]/255.0) : 1.0f;
285-
}
257+
if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
258+
dimensions[2] = 4; //RGBA images
259+
else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
260+
dimensions[2] = 3; //RGB images
261+
else
262+
dimensions[2] = 1; //Greyscale images
263+
//For gray, return an x by y array, not an x by y by 1
264+
int num_dims = (info_ptr->color_type & PNG_COLOR_MASK_COLOR) ? 3 : 2;
265+
266+
double max_value = (1 << ((bit_depth < 8) ? 8 : bit_depth)) - 1;
267+
PyArrayObject *A = (PyArrayObject *) PyArray_SimpleNew(num_dims, dimensions, PyArray_FLOAT);
268+
269+
for (png_uint_32 y = 0; y < height; y++) {
270+
png_byte* row = row_pointers[y];
271+
for (png_uint_32 x = 0; x < width; x++) {
272+
size_t offset = y*A->strides[0] + x*A->strides[1];
273+
if (bit_depth == 16) {
274+
png_uint_16* ptr = &reinterpret_cast<png_uint_16*> (row)[x * dimensions[2]];
275+
for (png_uint_32 p = 0; p < dimensions[2]; p++)
276+
*(float*)(A->data + offset + p*A->strides[2]) = (float)(ptr[p]) / max_value;
277+
} else {
278+
png_byte* ptr = &(row[x * dimensions[2]]);
279+
for (png_uint_32 p = 0; p < dimensions[2]; p++)
280+
{
281+
*(float*)(A->data + offset + p*A->strides[2]) = (float)(ptr[p]) / max_value;
282+
}
283+
}
286284
}
287285
}
288-
286+
289287
//free the png memory
290288
png_read_end(png_ptr, info_ptr);
291289
png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);

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