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video-converter: Fix RGB-XYZ-RGB conversion

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The matrices were in the wrong order.
Instead of the conversion matrix being
  _ XYZ_TO_RGB_output * RGB_TO_XYZ_input * input_RGB
It was
  _ RGB_TO_XYZ_input * XYZ_TO_RGB_output * input_RGB
This commit is contained in:
Edward Hervey 2019-11-08 15:13:59 +01:00 committed by Edward Hervey
parent 2d65683658
commit df35256dad
1 changed files with 25 additions and 2 deletions
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27
gst-libs/gst/video/video-converter.c
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@ -1755,26 +1755,49 @@ chain_convert (GstVideoConverter * convert, GstLineCache * prev, gint idx)
if (!same_primaries) {
const GstVideoColorPrimariesInfo *pi;
/* Convert from RGB_input to RGB_output via XYZ
* res = XYZ_to_RGB_output ( RGB_to_XYZ_input ( input ) )
* or in matricial form:
* RGB_output = XYZ_to_RGB_output_matrix * RGB_TO_XYZ_input_matrix * RGB_input
*
* The RGB_input is the pre-existing convert_matrix
* The convert_matrix will become the RGB_output
*/
/* Convert input RGB to XYZ */
pi = gst_video_color_primaries_get_info (convert->in_info.colorimetry.
primaries);
/* Get the RGB_TO_XYZ_input_matrix */
color_matrix_RGB_to_XYZ (&p1, pi->Rx, pi->Ry, pi->Gx, pi->Gy, pi->Bx,
pi->By, pi->Wx, pi->Wy);
GST_DEBUG ("to XYZ matrix");
color_matrix_debug (&p1);
GST_DEBUG ("current matrix");
/* convert_matrix = RGB_TO_XYZ_input_matrix * input_RGB */
color_matrix_multiply (&convert->convert_matrix, &convert->convert_matrix,
&p1);
color_matrix_debug (&convert->convert_matrix);
/* Convert XYZ to output RGB */
pi = gst_video_color_primaries_get_info (convert->out_info.colorimetry.
primaries);
/* Calculate the XYZ_to_RGB_output_matrix
* * Get the RGB_TO_XYZ_output_matrix
* * invert it
* * store in p2
*/
color_matrix_RGB_to_XYZ (&p2, pi->Rx, pi->Ry, pi->Gx, pi->Gy, pi->Bx,
pi->By, pi->Wx, pi->Wy);
color_matrix_invert (&p2, &p2);
GST_DEBUG ("to RGB matrix");
color_matrix_debug (&p2);
color_matrix_multiply (&convert->convert_matrix, &convert->convert_matrix,
&p2);
/* Finally:
* convert_matrix = XYZ_to_RGB_output_matrix * RGB_TO_XYZ_input_matrix * RGB_input
* = XYZ_to_RGB_output_matrix * convert_matrix
* = p2 * convert_matrix
*/
color_matrix_multiply (&convert->convert_matrix, &p2,
&convert->convert_matrix);
GST_DEBUG ("current matrix");
color_matrix_debug (&convert->convert_matrix);
}