Actually, it’s possible to optimize it a little bit :)
intersectionRect is useless, it’s defined by the bounding box of the tested object.
Math.floor is useless too if you base the whole work on  bitmapData.
Matrix calculations are useless too : only 4 substractions is needed. 
BlendMode is useless : if you base the find-color function on static colors, you can easily know (via trace) what color you’re looking for if collide

Here is an exemple :

//1) At the beginning, before the collision detection process :

//bgData is the bitmapData of the background
//mcData is the bitmapData of the moving object

var bgData:BitmapData = new BitmapData(100, 100, true, 0xff123456);var mcData:BitmapData = new BitmapData(100, 100, true, 0xff987654);

//We assume that the position of the background  are 0,0
//mcx = the position x of the moving object 
//mcy = the position y of the moving object

var mcx:int = 75;var mcy:int = 95;

//I set defined colors to my objects//I want a red-color with 0.5 alpha for the backgroundbgData.colorTransform(bgData.rect, new ColorTransform(0, 0, 0, 1, 255, 0, 0, 255));
bgData.colorTransform(bgData.rect, new ColorTransform(1, 1, 1, 0.5)); 

//and a green_color with 0.5 alpha for the moving object 

mcData.colorTransform(mcData.rect, new ColorTransform(0, 0, 0, 1, 0, 255, 0, 255));
mcData.colorTransform(mcData.rect, new ColorTransform(1, 1, 1, 0.5));//I set a new Rectangle  and a new Point that I will use in collision detection processvar rect:Rectangle = new Rectangle();var pt:Point = new Point();//I get width & height of background into variablesvar bgw:int = bgData.width;var bgh:int = bgData.height;//now, still at start, I want to know what will be the collision colorvar test:BitmapData = mcData.clone();test.copyPixels(bgData,mcData.rect,new Point(),null,null,true);var collisionColor:int = test.getPixel32(1,1);//2)now that all is ready, I can process the collision detection fastly :)//I’m looking for bounding  intersectionsrect.width = bdw – mcx;rect.height = bgh – mcy;if(rect.width < 0 || rect.height doesn’t colliderect.x = mcx;
rect.y = mcy;var productData:BitmapData = mc.clone(); productData.copyPixels(bgData, rect,pt, null, null, true);trace(“collisionRect = “+productData.getColorBoundsRect(0xffffffff,
collisionColor , true) );++

var wrapper:Sprite = new Sprite();
addChild(wrapper);

var glyph:Sprite;

var existingGlyphs:Sprite = new Sprite();
for (var i:uint; i < 50; i++)
{
glyph = new Clef();
glyph.x = i * 10;
existingGlyphs.addChild(glyph);
}
wrapper.addChild(existingGlyphs);

glyph = new Clef();
glyph.y = 20;
//addChild(glyph);
//wrapper.addChild(glyph);

var collision:Rectangle = PixelPerfectCollisionDetection.getCollisionRect(glyph, existingGlyphs, wrapper, true);
//var collision:Rectangle = HitTest.complexIntersectionRectangle(existingGlyphs, glyph);
existingGlyphs.x += collision.width;
trace(collision);
addChild(glyph);

Notice that glyph is not added to the stage until after the collision detection. The traced output is (x=-14, y=-26, w=0, h=0). However, if I add the glyph to wrapper before the detection, the output is (x=-9, y=-25, w=22, h=48) which is correct. Note that these “glyphs” are symbols with a registration point in the center. I’ll try to dig into it a bit but if you post a fix that’d be awesome to hear about.

THANKS :D