Til det skal du benytte GDI+
Start eventuelt her:
http://msdn.microsoft.com/library/en-us/cpref/html/frlrfSystemDrawing.asp(den her bruger jeg... stjålet fra nettet, men kan ikke lige finde den..)
Image Blend(Image image1, Image image2, float alpha)
{
Image image3 = image1.Clone() as Image;
using(Graphics g = Graphics.FromImage(image3))
{
using(ImageAttributes ia = new ImageAttributes())
{
ColorMatrix matrix = new ColorMatrix();
matrix.Matrix00 = 1; // Red
matrix.Matrix11 = 1; // Green
matrix.Matrix22 = 1; // Blue
matrix.Matrix33 = alpha;
matrix.Matrix44 = 1; // w
ia.SetColorMatrix(matrix);
g.DrawImage(image2, new Rectangle(0, 0, image2.Width,
image2.Height), 0, 0, image2.Width, image2.Height, GraphicsUnit.Pixel, ia);
}
}
return image3;
}