It's indeed much faster (five times faster than transforming to grey scale),
though the results I'm getting are incorrect (the other 2 methods seems to
return consistently similar results, though trasnforming to HLS takes about
3200 ms for a 1152 x 864 image, and transform to grey scale takes around 130
ms).
It could be the case that I'm doing it the wrong way, of course... This is
the code I'm using.
function getAverageFromScaledBitmap(src:DisplayObject):Number {
var dest:BitmapData = new BitmapData(1,1);
var mat:Matrix = new Matrix();
var sx:Number = 1 / src.width;
var sy:Number = 1 / src.height;
mat.scale(sx,sy);
dest.draw(src,mat,null,null,null,true);
var hls:Object = ColorUtils.RGBtoHLS(dest.getPixel(0,0));
return hls.l;
}
Cheers
Juan Pablo Califano
2009/3/29 Ian Thomas <i...@eirias.net>
> On Sun, Mar 29, 2009 at 8:14 PM, Juan Pablo Califano
> <califa010.flashcod...@gmail.com> wrote:
> > As it's been said already, you could try converting to HLS and the get
> the
> > average luminance (brigthness). Here's a handy class to convert from RGB
> to
> > HSL and viceversa.
> >
> > http://www.dreaminginflash.com/2007/11/19/hls-to-rgb-rgb-to-hls/
> > Another approach, which might be faster (but you'd have to test it to see
> if
> > that's true), could be transforming to bitmap to a grey scale. You would
> > then know how black / white each pixel is, so you could get the average
> > value by adding the value of each pixel and dividing for the total number
> of
> > pixels. Instead of reading the whole pixel value, you can just read one
> > channel, because since it' s a grey scale, the three color channels will
> be
> > equal.
>
> If you're going to test any kind of average pixel value, it'd be far
> faster to take a bitmap copy of the frame scaled to 1 pixel x 1 pixel
> (with smoothing on) - and just read the colour value of that pixel...
>
> HTH,
> Ian
> _______________________________________________
> Flashcoders mailing list
> Flashcoders@chattyfig.figleaf.com
> http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
>
_______________________________________________
Flashcoders mailing list
Flashcoders@chattyfig.figleaf.com
http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
