C# code to overlay one image over another

using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;


        public static Bitmap OverlayImage(Image background, Image foreground, Point foregroundLocation, Size foregroundSize, float opacity, bool resizeBackground)
        {
            Bitmap returnValue = null;
            Graphics returnValueGraphics = null;
            int backgroundHeight = background.Height;
            Point backgroundLocation = new Point(0, 0);
            int backgroundWidth = background.Width;
            int foregroundHeight = foreground.Height;
            int foregroundWidth = foreground.Width;
            int newHeight = 0;
            int newWidth = 0;

            if (false == resizeBackground)
            {
                newHeight = backgroundHeight;
                newWidth = backgroundWidth;
            }
            else
            {
                if (foregroundLocation.X < 0)
                {
                    backgroundLocation = new Point(Math.Abs(foregroundLocation.X), backgroundLocation.Y);
                    foregroundLocation = new Point(0, foregroundLocation.Y);
                }
                if (foregroundLocation.Y < 0)
                {
                    backgroundLocation = new Point(backgroundLocation.X, Math.Abs(foregroundLocation.Y));
                    foregroundLocation = new Point(foregroundLocation.X, 0);
                }
                newHeight = Math.Max((backgroundLocation.Y + backgroundHeight), (foregroundLocation.Y + Math.Min (foregroundHeight, foregroundSize.Height)));
                newWidth = Math.Max((backgroundLocation.X + backgroundWidth), (foregroundLocation.X + Math.Min (foregroundWidth, foregroundSize.Width)));
            }
            returnValue = new Bitmap(newWidth, newHeight, PixelFormat.Format32bppArgb);
            returnValue.SetResolution(background.HorizontalResolution, background.VerticalResolution);
            returnValueGraphics = Graphics.FromImage(returnValue);
            returnValueGraphics.SmoothingMode = SmoothingMode.AntiAlias;
            returnValueGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
            returnValueGraphics.DrawImage(
                background
            , new Rectangle(backgroundLocation, background.Size)
            , 0
            , 0
            , backgroundWidth
            , backgroundHeight
            , GraphicsUnit.Pixel
            );

            ImageAttributes imageAttributes = new ImageAttributes();
            float[][] colorMatrixElements = {
                                                new float[] {1.0f,  0.0f,  0.0f,  0.0f, 0.0f},
                                                new float[] {0.0f,  1.0f,  0.0f,  0.0f, 0.0f},
                                                new float[] {0.0f,  0.0f,  1.0f,  0.0f, 0.0f},
                                                new float[] {0.0f,  0.0f,  0.0f,  opacity, 0.0f},
                                                new float[] {0.0f,  0.0f,  0.0f,  0.0f, 1.0f}};
            ColorMatrix colorMatrix = new ColorMatrix(colorMatrixElements);
            imageAttributes.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
            returnValueGraphics.DrawImage(
                foreground
            , new Rectangle(foregroundLocation, foregroundSize)
            , 0
            , 0
            , foreground.Width
            , foreground.Height
            , GraphicsUnit.Pixel
            , imageAttributes
            );
            returnValueGraphics.Dispose();

            return (returnValue);
        }