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具体算法请参看《vb.net 教程 5-13 图像处理之像素处理 6》

 

 

 

黑白：

 

 

 

    '黑白1

    'http://blog.csdn.net/uruseibest

    Private Sub btn2Color1_Click(sender As Object, e As EventArgs) Handles btn2Color1.Click

        Dim destImg As New Bitmap(sourceImg.Width, sourceImg.Height)

        Dim sourceData As BitmapData = sourceImg.LockBits(New Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb)

        Dim destData As BitmapData = destImg.LockBits(New Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb)

 

        Dim pSource As IntPtr = sourceData.Scan0

        Dim allBytes As Integer = sourceData.Stride * sourceData.Height

        Dim rgbvalues() As Byte

        ReDim rgbvalues(allBytes - 1)

        Marshal.Copy(pSource, rgbvalues, 0, allBytes)

 

        Dim pos As Integer = 0

        Dim R, G, B As Integer

        Dim avgValue As Integer

 

        For j As Integer = 0 To sourceData.Height - 1

            For i As Integer = 0 To sourceData.Width - 1

                B = rgbvalues(pos)

                G = rgbvalues(pos + 1)

                R = rgbvalues(pos + 2)

                avgValue = (B + G + R) / 3

                If avgValue >= 128 Then avgValue = 255 Else avgValue = 0

                rgbvalues(pos) = avgValue

                rgbvalues(pos + 1) = avgValue

                rgbvalues(pos + 2) = avgValue

 

                pos = pos + 3

            Next

            pos = pos + sourceData.Stride - sourceData.Width * 3

        Next

 

        Dim pDest As IntPtr = destData.Scan0

        Marshal.Copy(rgbvalues, 0, pDest, allBytes)

 

        sourceImg.UnlockBits(sourceData)

        destImg.UnlockBits(destData)

 

        picDest.Image = destImg

    End Sub

 

 

 

 

 

 

 

 

 

 

 

 

    '黑白2

    'http://blog.csdn.net/uruseibest

    Private Sub btn2Color2_Click(sender As Object, e As EventArgs) Handles btn2Color2.Click

        Dim destImg As New Bitmap(sourceImg.Width, sourceImg.Height)

        Dim sourceData As BitmapData = sourceImg.LockBits(New Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb)

        Dim destData As BitmapData = destImg.LockBits(New Rectangle(0, 0, sourceImg.Width, sourceImg.Height), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb)

 

        Dim pSource As IntPtr = sourceData.Scan0

        Dim allBytes As Integer = sourceData.Stride * sourceData.Height

        Dim rgbvalues() As Byte

        ReDim rgbvalues(allBytes - 1)

        Marshal.Copy(pSource, rgbvalues, 0, allBytes)

 

        Dim pos As Integer = 0

        Dim R, G, B As Integer

 

        Dim HistGram(255) As Integer

 

        For j As Integer = 0 To sourceData.Height - 1

            For i As Integer = 0 To sourceData.Width - 1

                R = rgbvalues(pos + 2)

                HistGram(R) += 1

                pos = pos + 3

            Next

            pos = pos + sourceData.Stride - sourceData.Width * 3

        Next

 

        Dim threshold As Integer

 

        Dim allSum, allCount As Integer

        For k As Integer = 0 To 255

            allCount += HistGram(k)

            allSum += k * HistGram(k)

        Next

        threshold = allSum / allCount

 

        pos = 0

        For j As Integer = 0 To sourceData.Height - 1

            For i As Integer = 0 To sourceData.Width - 1

                R = rgbvalues(pos + 2)

                If R >= threshold Then R = 255 Else R = 0

 

                rgbvalues(pos) = R

                rgbvalues(pos + 1) = R

                rgbvalues(pos + 2) = R

 

                pos = pos + 3

            Next

            pos = pos + sourceData.Stride - sourceData.Width * 3

        Next

 

 

        Dim pDest As IntPtr = destData.Scan0

        Marshal.Copy(rgbvalues, 0, pDest, allBytes)

 

        sourceImg.UnlockBits(sourceData)

        destImg.UnlockBits(destData)

 

        picDest.Image = destImg

    End Sub

 

学习更多vb.net知识，请参看 vb.net 教程 目录

 

 

 

 

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版权声明：本文为CSDN博主「VB.Net」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。

原文链接：https://blog.csdn.net/uruseibest/article/details/70544017