If you need to create 4 channel image from 3 channel image you may consider using ippiCopy_8u_C3AC4R function, which will copy your source 3 channel image into destination 4 channel image. The fourth (alpha) channel values will not be changed in destination image.
If you need to create 4 channel image from 3 channel image you may consider using ippiCopy_8u_C3AC4R function, which will copy your source 3 channel image into destination 4 channel image. The fourth (alpha) channel values will not be changed in destination image.