Question

I’m working on a task that includes image processing. I’ve found out, that I’m repeating one code over and over (DRY alert) and I’m just curious, whether there is a way to avoid it.

The code is :

for (int x = 0; x < image.Width; x++)
{
    for (int y = 0; y < image.Height; y++)
    {
        byte pixelValue = Convert.ToByte(Byte.MaxValue * image.GetPixel(x, y).GetBrightness());
        //Do something with pixelValue
    }
}

The variety of tasks is wide, once I’m creating histogram, then I’m thresholding the image etc…. I feel there might be some solution using delegates, but I only have limited experience with them and clearly this is not the most important to think of.

Can you propose a solution in .NET Framework 2.0 as well?

Thanks

Answer 1

You could do it like this:

public static void ProcessPixelValues(Image image, Action<int, int, byte> processPixelValue)
{
    for (int x = 0; x < image.Width; x++)
    {
        for (int y = 0; y < image.Height; y++)
        {
            byte pixelValue = Convert.ToByte(Byte.MaxValue * image.GetPixel(x,         y).GetBrightness());

            processPixelValue(x, y, pixelValue);
        }
    }
}

public static void PrintPixelValuesOfImage(Image image)
{
    Action<int, int, byte> processPixelValue = 
        (x, y, pixelValue) => Console.WriteLine("The pixel value of [{0},{1}] is {2}", x, y, pixelValue);

    ProcessPixelValues(image, processPixelValue);
}

C# 2.0 Code

public delegate void ProcessPixelValueCallback(int x, int y, byte pixelValue);  

public static void ProcessPixelValues(Image image, ProcessPixelValueCallback processPixelValue)
{
    for (int x = 0; x < image.Width; x++)
    {
        for (int y = 0; y < image.Height; y++)
        {
            byte pixelValue = Convert.ToByte(Byte.MaxValue * image.GetPixel(x,         y).GetBrightness());

            processPixelValue(x, y, pixelValue);
        }
    }
}

public static void PrintPixelValuesOfImage(Image image)
{
    ProcessPixelValueCallback processPixelValue = delegate(int x, int y, byte pixelValue)
    {
        Console.WriteLine("The pixel value of [{0},{1}] is {2}", x, y, pixelValue);
    };

    ProcessPixelValues(image, processPixelValue);
}