Re: 16 bits = 15 bits in Photoshop?
Re: 16 bits = 15 bits in Photoshop?
- Subject: Re: 16 bits = 15 bits in Photoshop?
- From: Chris Cox <email@hidden>
- Date: Thu, 14 Apr 2005 18:07:44 -0700
At 9:43 PM -0700 4/13/05, email@hidden wrote:
Date: Thu, 14 Apr 2005 08:54:29 +1000
From: Graeme Gill <email@hidden>
Subject: Re: 16 bits = 15 bits in Photoshop?
One obvious advantage of a 16 bit representation with a maximum value
of 2^15, is that it's fast to multiply or divide by the maximum value
(or a power of 2 multiple of the maximum value) You simply use a shift.
Something like MMX/SSE doesn't have a vector divide or multiply instruction
that is as fast as simply shifting.
Bingo!
An integer divide can be around 30 times slower than an integer shift.
And integer divides on vector hardware are pretty tricky (not
impossible, though).
Performance was the big consideration for using a 0..32768
representation - and it looks like that representation will continue
to have large performance benefits into the foreseeable future.
Chris
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden