Re: float to int (kinda OT)

• Subject: Re: float to int (kinda OT)
• From: Chris Cox <email@hidden>
• Date: Thu, 21 Oct 2004 13:09:01 -0700
• Delivered-to: email@hidden
• Delivered-to: email@hidden

	r = (a * r) >> 8;
	g = (a * g) >> 8;
	b = (a * b) >> 8;

Ouch - No.
255 * 255 / 256 = 254
Even rounding won't fix that mistake.

When you multiply 8 bit components, you have to divide by 255.
Fortunately, there are some tricks to do that without using an actual divide.

Note that the right shift by 8 is an approximation to dividing by 255, but it shouldn't make that much difference.

I hope you don't ship applications that do that.
And you still should use rounding.

Chris
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