+#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+/* reduce RGB files to grayscale, with or without alpha
+ * using the equation given in Poynton's ColorFAQ at
+ * <http://www.inforamp.net/~poynton/>
+ * Copyright (c) 1998-01-04 Charles Poynton poynton@inforamp.net
+ *
+ * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
+ *
+ * We approximate this with
+ *
+ * Y = 0.211 * R + 0.715 * G + 0.074 * B
+ *
+ * which can be expressed with integers as
+ *
+ * Y = (54 * R + 183 * G + 19 * B)/256
+ *
+ * The calculation is to be done in a linear colorspace.
+ *
+ * Other integer coefficents can be used via png_set_rgb_to_gray().
+ */
+int
+png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
+
+{
+ png_uint_32 i;
+
+ png_uint_32 row_width = row_info->width;
+ int rgb_error = 0;
+
+ png_debug(1, "in png_do_rgb_to_gray\n");
+ if (
+#if defined(PNG_USELESS_TESTS_SUPPORTED)
+ row != NULL && row_info != NULL &&
+#endif
+ (row_info->color_type & PNG_COLOR_MASK_COLOR))
+ {
+ png_byte rc = png_ptr->rgb_to_gray_red_coeff;
+ png_byte gc = png_ptr->rgb_to_gray_green_coeff;
+ png_byte bc = png_ptr->rgb_to_gray_blue_coeff;
+
+ if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+ {
+ if (row_info->bit_depth == 8)
+ {
+#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+ if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+
+ for (i = 0; i < row_width; i++)
+ {
+ png_byte red = png_ptr->gamma_to_1[*(sp++)];
+ png_byte green = png_ptr->gamma_to_1[*(sp++)];
+ png_byte blue = png_ptr->gamma_to_1[*(sp++)];
+ if(red != green || red != blue)
+ {
+ rgb_error |= 1;
+ *(dp++) = png_ptr->gamma_from_1[
+ (rc*red+gc*green+bc*blue)>>8];
+ }
+ else
+ *(dp++) = *(sp-1);
+ }
+ }
+ else
+#endif
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_byte red = *(sp++);
+ png_byte green = *(sp++);
+ png_byte blue = *(sp++);
+ if(red != green || red != blue)
+ {
+ rgb_error |= 1;
+ *(dp++) = (rc*red+gc*green+bc*blue)>>8;
+ }
+ else
+ *(dp++) = *(sp-1);
+ }
+ }
+ }
+
+ else /* RGB bit_depth == 16 */
+ {
+#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+ if (png_ptr->gamma_16_to_1 != NULL &&
+ png_ptr->gamma_16_from_1 != NULL)
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 red, green, blue, w;
+
+ red = ((*(sp))<<8) | *(sp+1); sp+=2;
+ green = ((*(sp))<<8) | *(sp+1); sp+=2;
+ blue = ((*(sp))<<8) | *(sp+1); sp+=2;
+
+ if(red == green && red == blue)
+ w = red;
+ else
+ {
+ png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff) >>
+ png_ptr->gamma_shift][red>>8];
+ png_uint_16 green_1 = png_ptr->gamma_16_to_1[(green&0xff) >>
+ png_ptr->gamma_shift][green>>8];
+ png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff) >>
+ png_ptr->gamma_shift][blue>>8];
+ png_uint_16 gray16 = (rc * red_1 + gc * green_1
+ + bc * blue_1)>>8;
+ w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
+ png_ptr->gamma_shift][gray16 >> 8];
+ rgb_error |= 1;
+ }
+
+ *(dp++) = (w>>8) & 0xff;
+ *(dp++) = w & 0xff;
+ }
+ }
+ else
+#endif
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 red, green, blue, gray16;
+
+ red = ((*(sp))<<8) | *(sp+1); sp+=2;
+ green = ((*(sp))<<8) | *(sp+1); sp+=2;
+ blue = ((*(sp))<<8) | *(sp+1); sp+=2;
+
+ if(red != green || red != blue)
+ rgb_error |= 1;
+ gray16 = (rc * red + gc * green + bc * blue)>>8;
+ *(dp++) = (gray16>>8) & 0xff;
+ *(dp++) = gray16 & 0xff;
+ }
+ }
+ }
+ }
+ if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ {
+ if (row_info->bit_depth == 8)
+ {
+#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+ if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_byte red = png_ptr->gamma_to_1[*(sp++)];
+ png_byte green = png_ptr->gamma_to_1[*(sp++)];
+ png_byte blue = png_ptr->gamma_to_1[*(sp++)];
+ if(red != green || red != blue)
+ rgb_error |= 1;
+ *(dp++) = png_ptr->gamma_from_1
+ [(rc*red + gc*green + bc*blue)>>8];
+ *(dp++) = *(sp++); /* alpha */
+ }
+ }
+ else
+#endif
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_byte red = *(sp++);
+ png_byte green = *(sp++);
+ png_byte blue = *(sp++);
+ if(red != green || red != blue)
+ rgb_error |= 1;
+ *(dp++) = (gc*red + gc*green + bc*blue)>>8;
+ *(dp++) = *(sp++); /* alpha */
+ }
+ }
+ }
+ else /* RGBA bit_depth == 16 */
+ {
+#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
+ if (png_ptr->gamma_16_to_1 != NULL &&
+ png_ptr->gamma_16_from_1 != NULL)
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 red, green, blue, w;
+
+ red = ((*(sp))<<8) | *(sp+1); sp+=2;
+ green = ((*(sp))<<8) | *(sp+1); sp+=2;
+ blue = ((*(sp))<<8) | *(sp+1); sp+=2;
+
+ if(red == green && red == blue)
+ w = red;
+ else
+ {
+ png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff) >>
+ png_ptr->gamma_shift][red>>8];
+ png_uint_16 green_1 = png_ptr->gamma_16_to_1[(green&0xff) >>
+ png_ptr->gamma_shift][green>>8];
+ png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff) >>
+ png_ptr->gamma_shift][blue>>8];
+ png_uint_16 gray16 = (rc * red_1 + gc * green_1
+ + bc * blue_1)>>8;
+ w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
+ png_ptr->gamma_shift][gray16 >> 8];
+ rgb_error |= 1;
+ }
+
+ *(dp++) = (w>>8) & 0xff;
+ *(dp++) = w & 0xff;
+ *(dp++) = *(sp++); /* alpha */
+ *(dp++) = *(sp++);
+ }
+ }
+ else
+#endif
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 red, green, blue, gray16;
+ red = (*(sp)<<8) | *(sp+1); sp+=2;
+ green = (*(sp)<<8) | *(sp+1); sp+=2;
+ blue = (*(sp)<<8) | *(sp+1); sp+=2;
+ if(red != green || red != blue)
+ rgb_error |= 1;
+ gray16 = (rc * red + gc * green + bc * blue)>>8;
+ *(dp++) = (gray16>>8) & 0xff;
+ *(dp++) = gray16 & 0xff;
+ *(dp++) = *(sp++); /* alpha */
+ *(dp++) = *(sp++);
+ }
+ }
+ }
+ }
+ row_info->channels -= (png_byte)2;
+ row_info->color_type &= ~PNG_COLOR_MASK_COLOR;
+ row_info->pixel_depth = (png_byte)(row_info->channels *
+ row_info->bit_depth);
+ row_info->rowbytes = ((row_width *
+ row_info->pixel_depth + 7) >> 3);
+ }
+ return rgb_error;
+}
+#endif
+
projects / wxWidgets.git / blobdiff