可以百度一下：

http://tieba.baidu.com/p/1539909521

http://www.cnblogs.com/luluping/archive/2012/07/11/2585553.html

谢谢老大，成了，贴出代码分享：

Dim dlg As New OpenFileDialog \'定义一个新的OpenFileDialog
dlg.Filter= "图片文件|*.jpg;*.png" \'设置筛选器
If dlg.ShowDialog = DialogResult.Ok Then \'如果用户单击了确定按钮
   
    Dim omg As Image
    omg = GetImage(dlg.FileName)
    Dim Height As Integer = omg.Height
    Dim Width As Integer = omg.Width
    Dim newBitmap As Bitmap = New Bitmap(Width, Height)
    Dim oldBitmap As Bitmap = omg
    Dim pixel As Color
    For x As Integer = 1 To Width - 1
        For y As Integer = 1 To Height - 1
            pixel = oldBitmap.GetPixel(x, y)
            Dim r, g, b As Integer, Result As Integer = 0
            r = pixel.R
            g = pixel.G
            b = pixel.B
            Result = 0.7 * r + 0.2 * g + 0.1 * b
            newBitmap.SetPixel(x, y, Color.FromArgb(Result, Result, Result))
        Next
    Next

    Dim pb As WinForm.PictureBox = e.Form.Controls("PictureBox1")

     pb.Image = newbitmap
End If

上个图吧！