What does the mask parameter do in the threshold method of the BitmapData class?

I'm trying to replace a color and colors near it in a bitmap.

threshold() see开发者_JS百科ms to work but it seems to be that you have to specify the exact color "==" or all colors before or after the exact color "<" & ">" plus "<=" and ">=". I am hoping that the mask parameter will help me find a way to find a color and a dynamic range of colors before and after it to be replaced. What is its intended usage?

Per the comment below Example 1 and 2:

bit.threshold(bit, bit.rect, point, ">", 0xff000000, 0xffff0000, 0x00FF0000); 

bit.threshold(bit, bit.rect, point, ">", 0xff000000, 0xffff0000, 0x00EE0000);

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If you're trying to do a flood fill, I don't think the mask parameter will help you. The mask parameter lets you ignore parts of the color in the test. In your case, you want to take into account all the channels of the color, you just want the matching to be fuzzy.

e.g. If you want to replace all pixels where the red component is 0, you can set mask to 0x00FF0000, so it will ignore the other channels.

The implementation pseudo-code probably looks something like this:

input = readPixel()
value = input & mask
if(value operation threshold)
{
    writePixel(color)
}

Neither of your samples will produce anything because the mask limits the values to be between 0x00000000 and 0x00FF0000, then tests if they're greater than 0xFF000000.

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I have also done this and eventually, I have found it best to create my own threshold-method. You can find it below. Everything is explained in comment.

//_snapshot is a bitmapData-object
for(var i:int = 0; i <= _snapshot.width; i++)
{
    for(var j:int = 0; j <= _snapshot.height; j++)
    {
        //We get the color of the current pixel.
        var _color:uint = _snapshot.getPixel(i, j);                     

        //If the color of the selected pixel is between certain values set by the user, 
        //set the filtered pixel data to green. 
        //Threshold is a number (can be quite high, up to 50000) to look for adjacent colors in the colorspace.
        //_colorToCompare is the color you want to look for.
        if((_colorToCompare - (100 * _threshold)) <= _color && _color <= (_colorToCompare + (100 * _threshold)))
        {
            //This sets the pixel value.
            _snapshot.setPixel(i, j, 0x00ff00);
        }
        else
        {
            //If the pixel color is not within the desired range, set it's value to black.
            _snapshot.setPixel(i, j, 0x000000);
        }
    }
}