bit structure of ALPHA PImage type

Programming Questions

flokuehnle

bit structure of ALPHA PImage type

in Programming Questions • 2 years ago

hi,

there's lots written about color extraction, bit shifting, etc. but i can't find an answer to how many bits are used with the ALPHA PImage image type. 8, or 16?

I calculate the brightness of an RGB bitwise through

bright=(((col>>16)&0xFF) + ((col>>8)&0xFF) + ((col)&0xFF))/3;

but then i want to stuff it into an ALPHA PImage. is that just an 8 bit GGGGGGGG, or ist that 16 bit AAAAAAAAGGGGGGGG ?

sorry if that has been cleared somewhere, wasn't able to find someting.

thx fk.

Replies(4)

PhiLho

Re: bit structure of ALPHA PImage type

2 years ago

Not sure what is your GGG stuff, but basically, a color is a Java int, a 32 bit number. 24 bits are already used by the color information itself (R, G, B, 8 bits each), so only 8 bits remain to store the alpha information.

flokuehnle

Re: bit structure of ALPHA PImage type

2 years ago

alright. so i understand a grayscale color is also stored in 32 bits. how? do the respective 8 bits of R, G, and B (of an PImage type ALPHA) then simply have identical values?

PhiLho

Re: bit structure of ALPHA PImage type

2 years ago

Yes. There is no real grayscale mode in Processing.

flokuehnle

Re: bit structure of ALPHA PImage type

2 years ago

ok thanks.

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