Using transparency and alpha channels

- [Instructor] A clear view of how transparency works…is essential for post-production compositing.…There are several different flavors of transparency…providing different options.…Alpha channels and premultiplication…are the two main considerations with image transparency.…Usually when someone says alpha channel,…she or he means the transparency of a bitmap image.…Technically though, an alpha channel…is any auxiliary color channel that can store…any arbitrary pixel data,…and that's in addition…to the familiar red, green, and blue color channels.…

Professional file formats, such as TIF and EXR,…can include more than one alpha channel,…and these can store any data,…such as transparency or Z buffer depth.…Consumer and web-friendly formats, such as JPG and PNG,…either have no alpha support at all…or only allow one alpha channel for transparency only.…The bit depth of the channel determines the dynamic range…and number of possible values.…A 1-bit transparency channel only allows a pixel…to be fully opaque or fully transparent.…