使用
Graphics.DrawImage Method (Image,RectangleF,GraphicsUnit)方法.
Dim fileName = "C:\file.jpg"
Dim CropRect As New Rectangle(100,100,100)
Dim OriginalImage = Image.FromFile(fileName)
Dim CropImage = New Bitmap(CropRect.Width,CropRect.Height)
Using grp = Graphics.FromImage(CropImage)
grp.DrawImage(OriginalImage,New Rectangle(0,CropRect.Width,CropRect.Height),CropRect,GraphicsUnit.Pixel)
OriginalImage.Dispose()
CropImage.Save(fileName)
End Using