this demo requires Flash 10 Beta installed:

Extract from as3 language reference:

histogram() method

flash10 function histogram(hRect:Rectangle = null):Vector

Language Version : ActionScript 3.0
Player Version : Flash Player 10

Computes a 256 bin histogram of a BitmapData object.
The functions returns a vector of 4 number vectors.
The 4 number vectors represent the red, green, blue
and alpha components respectively. Each number vector
contains 256 values which represent the population count
of a indivual component value, from 0 to 255.

Parameters
hRect:Rectangle (default = null) — The area of the BitmapData
object that should be used.

Returns Vector

some code snippet from my demo:

function updateHistograms(bmpData:BitmapData,
sprites:Vector.<Sprite>):void {

// histogram is a Vector in two dimensions
// notice the interesting type Vector.<Vector.<Number>>
var hst:Vector.<Vector.<Number>> = bmpData.histogram();

var height:int=128; // height for diagrams
var maxValue:Number;
var value:Number;
var i:int;
var clr:int = 16; // value for bitwise shift left, start with red
// channel = 0:red, 1:green, 2:blue

for (var channel:int = 0; channel!=3; channel++) {

// find the max value on the histogram,
// i goes from 1 to 254,
// I discarded the 0 and 0xFF values to get a better balanced chart

maxValue =0.0;
for (i=1; i!=255; i++) {
value = hst[channel][i];
maxValue = value>maxValue ? value : maxValue;
}

with (sprites[channel].graphics) {
// empty and white background
clear();
beginFill(0xFFFFFF,1.0);
drawRect(0,0,255,height);
// draw a vertical line for each value with a corresponding color

i=0;
for each(value in hst[channel]) {
lineStyle(1.0,i<<clr) ;
moveTo(i,height);
lineTo(i++,Math.max(0.0,height-value*height/maxValue) );
}

}
clr -= 8;
}
}

In the demo I used Grant Skinner’s ColorMatrix for manipulating the image.

… two other new methods for BitmapData are getVector() and setVector() working just like older getPixels and setPixels-methods except with a Vector of uints, length = width x height:
like for instance copying pixels from 0,0 – 49,49 to 100,100 – 149,149:

var bmpVct:Vector.<uint> = bmpData.getVector(new Rectangle(0,0,50,50));
bmpData.setVector(new Rectangle(100,100,50,50),bmpVct);

And an example of experimental image manipulation of sorting by the pixel value

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