Result of alpha composition

[rdebeugny]

Hello,

I'm using AlphaComp_8uAC4R function. I want to be able to work in both modes : alpha-premultiplied mode and not premultiplied mode.
From my tests, it seems that the results of the function with ippAlphaOver are alpha-premultiplied :
I've the same results with
AlphaPremul(im1);
AlphaPremul(im2);
AlphaComp(im1,im2,ippAlphaOverPremul)
and
AlphaComp(im1,im2,ippAlphaOver)

Is it the expected behaviour ?
Is there a inverse function for AlphaPremul I could use to transform the result ?

Thanks

Raphael

[Ying_S_Intel]

Dear Customer,
If you would like further investigation on those Intel IPP functions, please submit an issue with details and test casesthrough Intel Premier Support at https://premier.intel.com.

Thanks,
Ying

Intel IPP Support