Fix byte-to-float conversion when using scene strips in sequencer with identical color spaces

Fix T50882: VSE: Blend Modes on Scenes do not layer properly
Fix T51002: Scene strip with Alpha over not working as expected

The byte-to-float conversion was being skipped if the color spaces of the sequence and the scene
are the same, which is the default, resulting in any non-float strips becoming invisible.

Reviewers: sergey

Differential Revision: https://developer.blender.org/D2635

1 files changed, 7 insertions, 2 deletions

diff --git a/source/blender/imbuf/intern/colormanagement.c b/source/blender/imbuf/intern/colormanagement.c
index fc382f02b2c..cdb8f2c6fa2 100644
--- a/source/blender/imbuf/intern/colormanagement.c
+++ b/source/blender/imbuf/intern/colormanagement.c
@@ -1759,9 +1759,14 @@ void IMB_colormanagement_transform_from_byte_threaded(float *float_buffer, unsig
 		return;
 	}
 	if (STREQ(from_colorspace, to_colorspace)) {
-		/* If source and destination color spaces are identical, skip
-		 * threading overhead and simply do nothing
+		/* Because this function always takes a byte buffer and returns a float buffer, it must
+		 * always do byte-to-float conversion of some kind. To avoid threading overhead
+		 * IMB_buffer_float_from_byte is used when color spaces are identical. See T51002.
 		 */
+		IMB_buffer_float_from_byte(float_buffer, byte_buffer,
+		                           IB_PROFILE_SRGB, IB_PROFILE_SRGB,
+		                           true,
+		                           width, height, width, width);
 		return;
 	}
 	cm_processor = IMB_colormanagement_colorspace_processor_new(from_colorspace, to_colorspace);