image processing - Red eye reduction algorithm

Question

I need to implement red eye reduction for an application I am working on.

Googling mostly provides links to commercial end-user products.

Do you know a good red eye reduction algorithm, which could be used in a GPL application?

Answer 1

I'm way late to the party here, but for future searchers I've used the following algorithm for a personal app I wrote.

First of all, the region to reduce is selected by the user and passed to the red eye reducing method as a center Point and radius. The method loops through each pixel within the radius and does the following calculation:

//Value of red divided by average of blue and green:
Pixel pixel = image.getPixel(x,y);
float redIntensity = ((float)pixel.R / ((pixel.G + pixel.B) / 2));
if (redIntensity > 1.5f)  // 1.5 because it gives the best results
{
    // reduce red to the average of blue and green
    bm.SetPixel(i, j, Color.FromArgb((pixel.G + pixel.B) / 2, pixel.G, pixel.B));
}

I really like the results of this because they keep the color intensity, which means the light reflection of the eye is not reduced. (This means eyes keep their "alive" look.)