Add image in center of an another image
Image parentImage = Image.FromFile(...);
Image childImage = Image.FromFile(...);
Graphics graphicsImage = Graphics.FromImage(parentImage);
int centerX = (parentImage.Width - childImage.Width) / 2;
int centerY = (parentImage.Height - childImage.Height) / 2;
graphicsImage.DrawImage(childImage, centerX, centerY, childImage.Width, childImage.Height);
parentImage.Save(outputFilePath);