Changes between Initial Version and Version 1 of Ticket #9750


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Timestamp:
Apr 26, 2022, 3:23:27 AM (4 years ago)
Author:
windowsair
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  • Ticket #9750 – Description

    initial v1  
    33I'm using ffmpeg's overlay filter with alpha premultiplied parameter. I noticed that when a completely transparent image was overlay to the background video, the output video was much brighter.
    44
    5 In the following demo, I will use RGBA8888 format images for overlay. Its use of RGBA (255,255,255,255,0) indicates full transparency (aka completely transparent white), and the result demonstrates a very noticeable brightening (the expected result should be unchanged, since the image is completely transparent).
     5In the following demo, I will use RGBA8888 format images for overlay. Its use of RGBA (255,255,255,0) indicates full transparency (aka completely transparent white), and the result demonstrates a very noticeable brightening (the expected result should be unchanged, since the image is completely transparent).
    66
    77ps: Using RGBA (0,0,0,0) (aka completely transparent black) also results in a brightened image.