User avatar
hcpizzi
Site Admin
Posts: 236
Joined: 09 Feb 2012, 12:40

Re: How to use transparent images In UE4

20 Mar 2018, 14:52

Hi,

That PNG doesn't have the color channels premultiplied by the alpha channel. The topmost, leftmost texel is RGBA (255, 221, 93, 0). If it had alpha premultiplied it should be (0, 0, 0, 0). What this setting does is it fixes a problem that comes from the way Unreal handles PNGs when they are imported, but it doesn't do the premultiplication. This forum post has a tool you can add to your pipeline to do the premultiplication:

viewtopic.php?f=3&t=1036&p=5842

Perhaps the meaning of the setting wasn't very clear.

I guess I could maybe add another option to do the premultiplication, if enough people find it useful.
 
ride_wind
Topic Author
Posts: 34
Joined: 07 Feb 2018, 03:33

Re: How to use transparent images In UE4

21 Mar 2018, 03:56

Hi,

That PNG doesn't have the color channels premultiplied by the alpha channel. The topmost, leftmost texel is RGBA (255, 221, 93, 0). If it had alpha premultiplied it should be (0, 0, 0, 0). What this setting does is it fixes a problem that comes from the way Unreal handles PNGs when they are imported, but it doesn't do the premultiplication. This forum post has a tool you can add to your pipeline to do the premultiplication:

viewtopic.php?f=3&t=1036&p=5842

Perhaps the meaning of the setting wasn't very clear.

I guess I could maybe add another option to do the premultiplication, if enough people find it useful.
Oh, I see, It work good using permultiplied image. Thanks.
Looking forward your option about premultiplication.

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