The storing of transparency information takes place in addition to the storing of other general image information.
In general, one differentiates between two types of alpha channels.
Separate and Integrated Alpha Channels
The separate alpha channel saves the transparency information (grayscale file) separately from the image file. Both files have to be imported in order to display the full and correct transparency of the file. In contrast to that, the integrated alpha channel saves the transparency information in a separate channel but integrated into the image file. Like this, the colour information of the alpha channel always matches the transparency information of the picture.
Bildschliff experts use alpha channels for clipping and soft-masking. If you want more information on this topic or our services, feel free to contact us.