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Blender 2.6 Bug Tracker: Browse

[#25713] VSE shows and renders wrong straight alpha gradient even after convert to premul is checked

Date:
2011-01-19 10:29		 Priority:
3
State:
Closed
Submitted by:
Ong Kuan Yang (oky) 		Assigned to:
Janne Karhu (jhk)
Category:
Sequencer		 Status:
Fixed / Closed
Relates to:
Duplicates:
Patches:
 
Summary:
VSE shows and renders wrong straight alpha gradient even after convert to premul is checked
Detailed description
To reproduce this:
go to sequence editor
insert a image with a alpha gradient (for me is a title bar)
Note: the image must be straight alpha
In the properties editor(press n key) check the convert to premul checkbox(required for straight alpha to work)
Now scrub through or render the animation with control F12
Notice that at some frames the image flashes( the image is different at some frames)
I believe that the "special" frame is the right way to render the alpha and the majority of frames are wrong. (I have stopped at the special frame in the blend file attached.)
However, when one render a specific frame (F12) it will change to the correct one.
I am using ubuntu and blender 2.56a.
Thanks. Please fix this.

Followup

Message
  • Date: 2011-01-19 16:52
  • Sender: Ton Roosendaal
  • The "special" frame appears to be the frame Blender loads with. There's something incorrect on load... we'll check it.
  • Date: 2011-01-21 02:44
  • Sender: Guillermo Espertino
  • Looks like it's not refreshing the alpha over operation. Apparently it happens with other operations too (for instance a transform effect).
    Notice that if you play the complete sequence, next time the playhead reproduces the sequence everything will look fine, but if you stop, scrub and then play it will flicker again.
  • Date: 2011-01-24 13:44
  • Sender: Janne Karhu
  • Assigned to self for investigation.
  • Date: 2011-01-28 02:00
  • Sender: Janne Karhu
  • Fix committed, thanks for the report, this was a good one!
  • Date: 2011-01-28 06:21
  • Sender: Ong Kuan Yang
  • thanks...but what went wrong? and is the correct premul rendered now?
  • Date: 2011-01-28 12:40
  • Sender: Janne Karhu
  • The premultiplication was applied twice for most of the frames as the sequencer cached the premultiplied image by accident instead of the original image. Now the premultiplication is only applied once like it's intended to.
 

Attached Files:

Name Date Download
title _bar.png 2011-01-19 10:29 Download
example.blend 2011-01-19 10:29 Download

Changes:

Field Old Value Date By
status_idOpen2011-01-28 02:00jhk
close_dateNone2011-01-28 02:00jhk
StatusInvestigate2011-01-28 02:00jhk
assigned_tonone2011-01-24 13:44jhk
StatusNew2011-01-19 16:52ton
File Added14634: title _bar.png2011-01-19 10:29oky
File Added14635: example.blend2011-01-19 10:29oky