how to turn an existing color image into a black-white image ?

Question

What diffrent approaches exists out there in actionscript 3.0 ? I found this library: mojocolors But this is more for graphics-color I guess…

Thx

Answer 1

In general, assuming that you start with an RGB image, you convert it to HSI color space and use the I (intensity) component.

Answer 2

To convert an image to grayscale, you need to iterate over each pixel in the image buffer and average the R, G and B component into one entity, then duplicate it three times to get the new color. pseudo-code (assuming 8bit color):

for each pixel in buffer: 
    pixel.rgb = ((pixel.red + pixel.green + pixel.blue) / 3) * 0x010101;

I am sure you can do something with Adobe's PixelBender to achieve this faster.

Answer 3

var n:Number = 1/3;
var matrix:Array = [n,n,n,0,0,
                    n,n,n,0,0,
                    n,n,n,0,0, 
                    0,0,0,1,0];

var cmf:ColorMatrixFilter = new ColorMatrixFilter(matrix);
bitmap.filters = [cmf];

Answer 4

Apply the filter created by this method to the DisplayObject that contains the image you want in black and white:

public static function createBlackAndWhiteFilter():ColorMatrixFilter {
 var rLum:Number = 0.2225;
 var gLum:Number = 0.7169;
 var bLum:Number = 0.0606;

 var bwMatrix:Array = [rLum, gLum, bLum, 0, 0, rLum, gLum, bLum, 0, 0, rLum, gLum, bLum, 0, 0, 0, 0, 0, 1, 0];  
 return new ColorMatrixFilter(bwMatrix);
}//createBlackAndWhiteFilter