C#圖像亮度對比度調節

        /// <summary>
        /// 圖像對比度調整
        /// </summary>
        /// <param name="b">原始圖</param>
        /// <param name="degree">對比度[-100, 100]</param>
        /// <returns></returns>
        public static Bitmap KiContrast(Bitmap b, int degree)
        {
            if (b == null)
            {
                return null;
            }

            if (degree < -100) degree = -100;
            if (degree > 100) degree = 100;

            try
            {

                double pixel = 0;
                double contrast = (100.0 + degree) / 100.0;
                contrast *= contrast;
                int width = b.Width;
                int height = b.Height;
                BitmapData data = b.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
                unsafe
                {
                    byte* p = (byte*)data.Scan0;
                    int offset = data.Stride - width * 3;
                    for (int y = 0; y < height; y++)
                    {
                        for (int x = 0; x < width; x++)
                        {
                            // 處理指定位置像素的對比度
                            for (int i = 0; i < 3; i++)
                            {
                                pixel = ((p[i] / 255.0 - 0.5) * contrast + 0.5) * 255;
                                if (pixel < 0) pixel = 0;
                                if (pixel > 255) pixel = 255;
                                p[i] = (byte)pixel;
                            } // i
                            p += 3;
                        } // x
                        p += offset;
                    } // y
                }
                b.UnlockBits(data);
                return b;
            }
            catch
            {
                return null;
            }
        } // end of Contrast

 

        /// <summary>
        /// 亮度
        /// </summary>
        /// <param name="a"></param>
        /// <param name="v"></param>
        /// <returns></returns>
        private static Bitmap BrightnessP(Bitmap a, int v)
        {
            System.Drawing.Imaging.BitmapData bmpData = a.LockBits(new Rectangle(0, 0, a.Width, a.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
            int bytes = a.Width * a.Height * 3;
            IntPtr ptr = bmpData.Scan0;
            int stride = bmpData.Stride;
            unsafe
            {
                byte* p = (byte*)ptr;
                int temp;
                for (int j = 0; j < a.Height; j++)
                {
                    for (int i = 0; i < a.Width * 3; i++, p++)
                    {
                        temp = (int)(p[0] + v);
                        temp = (temp > 255) ? 255 : temp < 0 ? 0 : temp;
                        p[0] = (byte)temp;
                    }
                    p += stride - a.Width * 3;
                }
            }
            a.UnlockBits(bmpData);
            return a;
        }