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Topic: fast grey (Read 1804 times) |
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st33d
 
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fast grey
« on: Apr 16th, 2005, 12:13am » |
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I currently get grey values of pixels like this:
Code:
float grey(color p){
int r=p>>16&0xff;
int g=p>>8&0xff;
int b=p&0xff;
return (r+g+b)/3;
}
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Is there a faster way of doing this with an integral return value? I've tried the function as an int but it's inaccurate and I'm calling this function a lot.
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I could murder a pint.
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fry
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Re: fast grey
« Reply #1 on: Apr 16th, 2005, 1:47am » |
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the quickest gray i know of (where gray is defined as "brightness")
max((value >> 16) & 0xff, (value >> 8 ) & 0xff, value & 0xff);
and to avoid putting it in a function, either just write that inline to your code, or use:
static final int gray(color p) {
return max((value >> 16) & 0xff, (value >> 8 ) & 0xff, value & 0xff);
}
"final" should make it a little faster (maybe inline it by the compiler) and static may help too, ymmv.
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| « Last Edit: Apr 16th, 2005, 1:47am by fry » |
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st33d
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Re: fast grey
« Reply #2 on: Apr 18th, 2005, 11:35pm » |
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Thank you. Seems to work fine. Static final doesn't seem to work within the API (I'm using Processing as a glorified photoshop filter these days - need to save). My experience is limited to using the API only. In what conditions does "static final" pass as opperable? Is there a link to a tutorial which could explain these Java conditions? (public, static and final I have seen but it's never really sunk in as the Processing API is much more straight-forward).
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I could murder a pint.
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