29 Luglio 2021

Pre-multiplied alpha blending

LiveBoard and its perfect transparency: pre-multiplied alpha blending

LiveBoard achieves its high quality CG-reputation also thanks to the blending technology that ClassX developers have used from the very beginning: pre-multiplication of the alpha. Meaning that the FILL channel that we mentioned above has a specific feature:

The values of the RGB components (our "fill") are, as the name implies, premultiplied by the alpha component - with premultiplied alpha the color information also carries the values of pixel’s opacity. You can find more information on the theory of this here, it is explained exquisitely in the blog of Bartosz Ciechanowski.

In terms offinal result, this alpha-premultiplication results in perfect transparency of partially and non-partially transparent shades that tend to complete transparency, such as flares. No strangely colored halos, no ugly artifacts will ruin the final result of your real-time broadcast graphics because LiveBoard makes sure with this technology that any transparent pixel stays as such and has no interfering RGB colour when the switcher blends the alpha channel (the "key") with the RGB channel (the "fill") that LiveBoard creates for every single frame.


ClassX srl, based in Italy, is a software house that produces high-performance, real-time broadcast graphics solutions

ClassX srl
c/o Villa Montecchio,
Via del Tiglio, 91 56012 Calcinaia (PI)
Opening hours for sales & support:
Monday - Friday
09:00 - 13:00, 15:00 - 19:00
Time Zone CEST
UTC/GMT + 2 (Rome Time)
ClassX IBC Project co-financed under Tuscany POR FESR 2014-2020
Cap. Soc. €50.000 i.v.
Reg. Imprese di Pisa N. 01351840507
R.E.A. PI-116996