请问那里有用vb.net写的图象处理程序代码的例子。

[laviewpbt]

找到一些，怎么都是用setpixel之类的方法做的，效率也太低下了吧，6.0里可以用DIB，.net里该怎么用呢？

[AprilSong]

用GDI+……

http://community.csdn.net/Expert/TopicView.asp?id=4369343

[AprilSong]

上面是基本的颜色矩阵操作
更复杂的就转成字节数组来做，和dib的图象处理是类似的
http://community.csdn.net/Expert/topic/4411/4411199.xml?temp=.1745722

[xiaoguanguan]

看msdn吧.比较详细呢.

[laviewpbt]

比如我要反色，则下面的两个循环之间该怎么写？

Private Function InvertBitmap(ByVal pBitmap As Bitmap) As Boolean
Dim width As Integer = pBitmap.Width
Dim height As Integer = pBitmap.Height
Dim rect As Rectangle = New Rectangle(0, 0, width, height)
Dim bitmapData As BitmapData = pBitmap.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb)
Dim stride As Integer = bitmapData.Stride
Dim RawData As IntPtr = bitmapData.Scan0
Dim x, y As Integer
For y = 0 To height
For x = 0 To width

Next
Next
pBitmap.UnlockBits(bitmapData)
Return True
End Function

[chenlin2000]

用marshal.readint32读取每一个像素值

[AprilSong]

只要反色的话，这样快得多～

Dim bmp As New Drawing.Bitmap("1.jpg")

Dim cm As New Drawing.Imaging.ColorMatrix
Dim ia As New Drawing.Imaging.ImageAttributes

cm.Matrix00 = -1
cm.Matrix11 = -1
cm.Matrix22 = -1

ia.SetColorMatrix(cm, Imaging.ColorMatrixFlag.Default, Imaging.ColorAdjustType.Bitmap)

Dim g As Graphics = Drawing.Graphics.FromImage(bmp)
g.DrawImage(bmp, New Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, bmp.Width, bmp.Height, GraphicsUnit.Pixel, ia)

PictureBox1.Image = bmp

[laviewpbt]

谢谢楼上，这个我知道，不过我想了解有没有快点的方法从bitmapData 中读取数据。在循环内频繁地调用marshal.readint32似乎不是个好注意。

[laviewpbt]

多谢AprilSong(X)

[chenlin2000]

把ptr中内容填充到一个数组中如何

[AprilSong]

用Marshal.Copy先转成数组要快得多～

Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown
Dim bmp As New Bitmap("1.jpg")

Dim t As Single

t = Microsoft.VisualBasic.DateAndTime.Timer
If e.Button = MouseButtons.Left Then
PictureBox1.Image = InvertBitmap(bmp)
Else
PictureBox1.Image = InvertBitmap2(bmp)
End If
t = Microsoft.VisualBasic.DateAndTime.Timer - t

Me.Text = "耗时：" & t
End Sub

Private Function InvertBitmap(ByVal pBitmap As Bitmap) As Bitmap
Dim width As Integer = pBitmap.Width
Dim height As Integer = pBitmap.Height
Dim rect As Rectangle = New Rectangle(0, 0, width, height)
Dim bitmapData As BitmapData = pBitmap.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format32bppRgb)
Dim stride As Integer = bitmapData.Stride
Dim RawData As IntPtr = bitmapData.Scan0

Dim i As Integer
Dim l As Integer = height * stride - 1
Dim b As Byte
Dim m As Byte = 255

For i = 0 To l
b = Marshal.ReadByte(RawData, i)
Marshal.WriteByte(RawData, i, m - b)
Next

pBitmap.UnlockBits(bitmapData)

Return pBitmap
End Function

Private Function InvertBitmap2(ByVal pBitmap As Bitmap) As Bitmap
Dim width As Integer = pBitmap.Width
Dim height As Integer = pBitmap.Height
Dim rect As Rectangle = New Rectangle(0, 0, width, height)
Dim bitmapData As BitmapData = pBitmap.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format32bppRgb)
Dim stride As Integer = bitmapData.Stride
Dim RawData As IntPtr = bitmapData.Scan0

Dim i As Integer
Dim l As Integer = height * stride - 1
Dim b(l) As Byte
Dim m As Byte = 255

Marshal.Copy(RawData, b, 0, l)
For i = 0 To l
b(i) = m - b(i)
Next
Marshal.Copy(b, 0, RawData, l)

pBitmap.UnlockBits(bitmapData)

Return pBitmap
End Function

[laidon]

偶买了本<<VB.net图形图像处理技术>>的书，光盘中有很多实例，但我觉得用.net还是msdn更详细，有原理。要实例和我联系吧，QQ71451437

[laviewpbt]

我试了下,好像GDI+的速度也并不是很慢阿,还有用colormatrix与Marshal.Copy两者的处理速度也差不到那里去的 .

[slhuang]

个人认为，图象处理不是VB。NET的优势。
有志于图象开发的话，还是用VC好用一点。