Søren,
I am attaching the output of 'svd diff' from the image directory with
identical changes to the code.
Let me know if I done it incorrectly.
On Thu, Mar 19, 2009 at 4:45 PM, Søren Hauberg <[email protected]> wrote:
> tor, 19 03 2009 kl. 14:36 -0400, skrev Eugeniy Mikhailov:
>> Thank you for applying the patch.
>> I have look at the pngread.cc a little bit more and find out that
>> the reason for wrong png to matrix conversion was essentially in the
>> load_canvas function of this source file.
>
> I think the patch looks good. Thanks for doing this. Could you possibly
> generate the patch using 'svn diff' as that'll make it easier for me to
> apply?
--
Eugeniy
Index: pngread.cc
===================================================================
--- pngread.cc (revision 5621)
+++ pngread.cc (working copy)
@@ -84,13 +84,14 @@
((pic->color_type == PNG_COLOR_TYPE_PALETTE) && (pic->bit_depth == 1)) )
dim(2) = 1;
- if (pic->bit_depth > 1 && pic->bit_depth < 8)
- pic->bit_depth = 8;
+ if (pic->bit_depth > 1 && pic->bit_depth < 8)
+ pic->bit_depth = 8; //this should never happen according to load_canvas code
int isAlfaChannelPresent = 0;
if ( pic->color_type & PNG_COLOR_MASK_ALPHA)
isAlfaChannelPresent=1;
+
NDArray out(dim);
dim.resize(2);
@@ -98,6 +99,8 @@
Array<int> coord = Array<int> (3);
+ int major_byte, minor_byte,row_pxl_position;
+ /* calculate the number of color channels (including alpha) per pixel */
int ElementsPerPixel=out.dims()(2)+isAlfaChannelPresent;
for (unsigned long j=0; j < pic->height; j++) {
coord(0) = j;
@@ -106,13 +109,42 @@
for (int c = 0; c < out.dims()(2); c++) {
coord(2) = c;
- out(coord) = pic->row_pointers[j][i*ElementsPerPixel+c];
+ switch(pic->bit_depth) {
+ case 8:
+ row_pxl_position=(i*ElementsPerPixel+c);
+ out(coord) = pic->row_pointers[j][row_pxl_position];
+ break;
+ case 16:
+ // converting big endian
+ row_pxl_position=2*(i*ElementsPerPixel+c);
+ major_byte=pic->row_pointers[j][row_pxl_position];
+ minor_byte=pic->row_pointers[j][row_pxl_position+1] ;
+ out(coord) = major_byte*256+minor_byte;
+ break;
+ default:
+ printf("do not know how to handle bit depth of %d\n",pic->bit_depth);
+ }
}
- if (isAlfaChannelPresent)
- alpha(j,i) = pic->row_pointers[j][i*ElementsPerPixel+(ElementsPerPixel-1)];
- else
- alpha(j,i) = 1;
- }
+ if (isAlfaChannelPresent) { // it always should according to load canvas code
+ switch(pic->bit_depth) {
+ case 8:
+ row_pxl_position=(i*ElementsPerPixel+ElementsPerPixel-1);
+ alpha(j,i) = pic->row_pointers[j][row_pxl_position];
+ break;
+ case 16:
+ // converting big endian
+ row_pxl_position=2*(i*ElementsPerPixel+ElementsPerPixel-1);
+ major_byte = pic->row_pointers[j][row_pxl_position];
+ minor_byte = pic->row_pointers[j][row_pxl_position+1];
+ alpha(j,i) = major_byte*256+minor_byte;
+ break;
+ default:
+ printf("do not know how to handle bit depth of %d\n",pic->bit_depth);
+ }
+ } else {
+ alpha(j,i) = 255;
+ }
+ }
}
out = out.squeeze();
@@ -197,7 +229,9 @@
png_set_palette_to_rgb(png_ptr);
}
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
- png_set_gray_1_2_4_to_8(png_ptr);
+ png_set_gray_1_2_4_to_8(png_ptr); // this function deprecated need to be redone
+ bit_depth=8;
+ info_ptr->bit_depth=bit_depth;
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) { //add alpha
png_set_tRNS_to_alpha(png_ptr);
@@ -206,21 +240,35 @@
// Always transform image to RGB
if (color_type == PNG_COLOR_TYPE_GRAY
|| color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ {
png_set_gray_to_rgb(png_ptr);
+ color_type= (color_type | PNG_COLOR_MASK_COLOR);
+ info_ptr->color_type=color_type;
+ }
// If no alpha layer is present, create one
- if (color_type == PNG_COLOR_TYPE_GRAY
- || color_type == PNG_COLOR_TYPE_RGB)
- png_set_add_alpha(png_ptr, 0xff, PNG_FILLER_AFTER);
+ if (!(color_type & PNG_COLOR_MASK_ALPHA))
+ {
+ png_set_add_alpha(png_ptr, 0xff, PNG_FILLER_AFTER);
+ color_type= (color_type | PNG_COLOR_MASK_ALPHA);
+ info_ptr->color_type=color_type;
+ }
if (bit_depth < 8) {
png_set_packing(png_ptr);
+ bit_depth=8;
+ info_ptr->bit_depth=bit_depth;
}
-
+
+ // Hey! Our signal could be small and in the lower bits,
+ // leave our data alone and do not decrease accuracy
+ // 16 -> 8 bits commented out
// For now, use 8-bit only
- if (bit_depth == 16) {
- png_set_strip_16(png_ptr);
- }
+ //if (bit_depth == 16) {
+ //png_set_strip_16(png_ptr);
+ //bit_depth=8;
+ //info_ptr->bit_depth=bit_depth;
+ //}
png_read_update_info(png_ptr,info_ptr);
------------------------------------------------------------------------------
Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
easily build your RIAs with Flex Builder, the Eclipse(TM)based development
software that enables intelligent coding and step-through debugging.
Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
_______________________________________________
Octave-dev mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/octave-dev
