Computing "average" of two colors
- by Francisco P.
This is only marginally programming related - has much more to do w/ colors and their representation.
I am working on a very low level app. I have an array of bytes in memory. Those are characters. They were rendered with anti-aliasing: they have values from 0 to 255, 0 being fully transparent and 255 totally opaque (alpha, if you wish).
I am having trouble conceiving an algorithm for the rendering of this font. I'm doing the following for each pixel:
// intensity is the weight I talked about: 0 to 255
intensity = glyphs[text[i]][x + GLYPH_WIDTH*y];
if (intensity == 255)
continue; // Don't draw it, fully transparent
else if (intensity == 0)
setPixel(x + xi, y + yi, color, base); // Fully opaque, can draw original color
else { // Here's the tricky part
// Get the pixel in the destination for averaging purposes
pixel = getPixel(x + xi, y + yi, base);
// transfer is an int for calculations
transfer = (int) ((float)((float) (255.0 - (float) intensity/255.0) * (float) color.red + (float) pixel.red)/2); // This is my attempt at averaging
newPixel.red = (Byte) transfer;
transfer = (int) ((float)((float) (255.0 - (float) intensity/255.0) * (float) color.green + (float) pixel.green)/2);
newPixel.green = (Byte) transfer;
// transfer = (int) ((float) ((float) 255.0 - (float) intensity)/255.0 * (((float) color.blue) + (float) pixel.blue)/2);
transfer = (int) ((float)((float) (255.0 - (float) intensity/255.0) * (float) color.blue + (float) pixel.blue)/2);
newPixel.blue = (Byte) transfer;
// Set the newpixel in the desired mem. position
setPixel(x+xi, y+yi, newPixel, base);
}
The results, as you can see, are less than desirable. That is a very zoomed in image, at 1:1 scale it looks like the text has a green "aura".
Any idea for how to properly compute this would be greatly appreciated.
Thanks for your time!
