图片（进度条）模糊

设置页面样式：

private void button1_Click(object sender, EventArgs e)//打开图片按钮

        {

            if (openFileDialog1.ShowDialog() == DialogResult.OK)

            {

                pictureBox1.Image = Image.FromFile(openFileDialog1.FileName);//显示图片

            }

        }

private void trackBar1_ValueChanged(object sender, EventArgs e)//模糊条

        {

            ChangeAlpha();

     }

private void ChangeAlpha()//图片模糊代码

        {

            pictureBox1.Refresh();//强制控件使其客户区无效，并立即重新绘制自己

            Bitmap source = new Bitmap(pictureBox1.Image); //声明

            Bitmap effect = new tmap(pictureBox1.Image.Width,pictureBox1.Image.Height); //声明

            Graphics _effect = Graphics.FromImage(effect);

            float[][] matrixItems ={new float[]{1,0,0,0,0},

                                      new float [] {0,1,0,0,0},

                                      new float []{0,0,1,0,0},

                                      new float []{0,0,0,0,0},

                                      new float[]{0,0,0,trackBar1.Value/255f,1}};

            ColorMatrix imgMatrix = new ColorMatrix(matrixItems);

            ImageAttributes imgEffect = new ImageAttributes();

            imgEffect.SetColorMatrix(imgMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);//SetColorMatrix设置指定类别的颜色调整矩阵

            if (source.Width <= 368)

            {

                _effect.DrawImage(source, new Rectangle(0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height), 0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height, GraphicsUnit.Pixel, imgEffect);//DrawImage图片拖拽具有六个参数（图片，矩形，位置X，位置Y，图片的宽度，图片的高度）

            }

            else

            {

                _effect.DrawImage(pictureBox1.Image, new Rectangle(0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height), 0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height, GraphicsUnit.Pixel, imgEffect);

            }

            pictureBox1.Image = effect;

        }                               

效果：