前言

这个Bitmap元素在我们处理图像显示相关时，它的身影就可以见到了。官方术语：封装 GDI+ 位图，此位图由图形图像及其属性的像素数据组成。 Bitmap 是用于处理由像素数据定义的图像的对象。操作对象最重要的两个方法GetPixel和SetPixel。

一、效果

1、光环效果

2、亮度调节

3、彩色转黑白

4、色温反转

5、马赛克

6、扩散效果

二、代码示例

1、光环效果

 if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;

                stopwatch.Restart();

                int width = newbitmap.Width;
                int height = newbitmap.Height;
                float cx = width / 2;
                float cy = height / 2;
                float maxDist = cx * cx + cy * cy;
                float currDist = 0, factor;
                Color pixel;

                for (int i = 0; i < width; i++)
                {
                    for (int j = 0; j < height; j++)
                    {
                        currDist = ((float)i - cx) * ((float)i - cx) + ((float)j - cy) * ((float)j - cy);
                        factor = currDist / maxDist;

                        pixel = newbitmap.GetPixel(i, j);
                        int red = (int)(pixel.R * (1 - factor));
                        int green = (int)(pixel.G * (1 - factor));
                        int blue = (int)(pixel.B * (1 - factor));
                        newbitmap.SetPixel(i, j, Color.FromArgb(red, green, blue));
                    }
                }

                stopwatch.Stop();
                lbTimer.Text = stopwatch.ElapsedMilliseconds.ToString() + " ms";
                pictureBox2.Image = newbitmap.Clone() as Image;
            }

2、亮度调节

if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                stopwatch.Reset();
                stopwatch.Restart();
                Color pixel;
                int red, green, blue;
                for (int x = 0; x < newbitmap.Width; x++)
                {
                    for (int y = 0; y < newbitmap.Height; y++)
                    {
                        pixel = newbitmap.GetPixel(x, y);
                        red = (int)(pixel.R * 0.6);
                        green = (int)(pixel.G * 0.6);
                        blue = (int)(pixel.B * 0.6);
                        newbitmap.SetPixel(x, y, Color.FromArgb(red, green, blue));
                    }
                }
                stopwatch.Stop();
                lbTimer.Text = stopwatch.ElapsedMilliseconds.ToString() + " ms";
                pictureBox2.Image = newbitmap.Clone() as Image;
            }

3、彩色转黑白

if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                stopwatch.Reset();
                stopwatch.Restart();
                Color pixel;
                int gray;
                for (int x = 0; x < newbitmap.Width; x++)
                {
                    for (int y = 0; y < newbitmap.Height; y++)
                    {
                        pixel = newbitmap.GetPixel(x, y);
                        gray = (int)(0.3 * pixel.R + 0.59 * pixel.G + 0.11 * pixel.B);
                        newbitmap.SetPixel(x, y, Color.FromArgb(gray, gray, gray));
                    }
                }
                stopwatch.Stop();
                lbTimer.Text = stopwatch.ElapsedMilliseconds.ToString() + " ms";
                pictureBox2.Image = newbitmap.Clone() as Image;
            }

4、色温反转

 if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                stopwatch.Restart();
                Color pixel;
                int red, green, blue;
                for (int x = 0; x < newbitmap.Width; x++)
                {
                    for (int y = 0; y < newbitmap.Height; y++)
                    {
                        pixel = newbitmap.GetPixel(x, y);
                        red = (int)(255 - pixel.R);
                        green = (int)(255 - pixel.G);
                        blue = (int)(255 - pixel.B);
                        newbitmap.SetPixel(x, y, Color.FromArgb(red, green, blue));
                    }
                }
                stopwatch.Stop();
                lbTimer.Text = stopwatch.ElapsedMilliseconds.ToString() + " ms";
                pictureBox2.Image = newbitmap.Clone() as Image;
            }

5、马赛克

if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                stopwatch.Reset();
                stopwatch.Restart();
                int RIDIO = 50;//马赛克的尺度，默认为周围两个像素
                for (int h = 0; h < newbitmap.Height; h += RIDIO)
                {
                    for (int w = 0; w < newbitmap.Width; w += RIDIO)
                    {
                        int avgRed = 0, avgGreen = 0, avgBlue = 0;
                        int count = 0;
                        //取周围的像素
                        for (int x = w; (x < w + RIDIO && x < newbitmap.Width); x++)
                        {
                            for (int y = h; (y < h + RIDIO && y < newbitmap.Height); y++)
                            {
                                Color pixel = newbitmap.GetPixel(x, y);
                                avgRed += pixel.R;
                                avgGreen += pixel.G;
                                avgBlue += pixel.B;
                                count++;
                            }
                        }

                        //取平均值
                        avgRed = avgRed / count;
                        avgBlue = avgBlue / count;
                        avgGreen = avgGreen / count;

                        //设置颜色
                        for (int x = w; (x < w + RIDIO && x < newbitmap.Width); x++)
                        {
                            for (int y = h; (y < h + RIDIO && y < newbitmap.Height); y++)
                            {
                                Color newColor = Color.FromArgb(avgRed, avgGreen, avgBlue);
                                newbitmap.SetPixel(x, y, newColor);
                            }
                        }
                    }
                }
                stopwatch.Stop();
                lbTimer.Text = stopwatch.ElapsedMilliseconds.ToString() + " ms";
                pictureBox2.Image = newbitmap.Clone() as Image;
            }

6、扩散效果

if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                stopwatch.Reset();
                stopwatch.Restart();
                Color pixel;
                int red, green, blue;
                int flag = 0;
                for (int x = 0; x < newbitmap.Width; x++)
                {
                    for (int y = 0; y < newbitmap.Height; y++)
                    {
                        Random ran = new Random();
                        int RankKey = ran.Next(-5, 5);
                        if (x + RankKey >= newbitmap.Width || y + RankKey >= newbitmap.Height || x + RankKey < 0 || y + RankKey < 0)
                        {
                            flag = 1;
                            continue;
                        }

                        pixel = newbitmap.GetPixel(x + RankKey, y + RankKey);
                        red = (int)(pixel.R);
                        green = (int)(pixel.G);
                        blue = (int)(pixel.B);
                        newbitmap.SetPixel(x, y, Color.FromArgb(red, green, blue));
                    }
                }
                stopwatch.Stop();
                lbTimer.Text = stopwatch.ElapsedMilliseconds.ToString();
                pictureBox2.Image = newbitmap.Clone() as Image;
            }