VB. Net simple processing pictures, black and white (class library - 7)

  Let's see , This picture makes us take pictures with mobile phones , Without treatment , Printed out is gray

stay Photoshop You can adjust the color scale , Choose black and then white , It can be clarified

  Pay attention to flattening when taking photos , This is the color mode of scanning , As a test

see VB.net How to deal with it  

Referenced in this article csdn Big guy's article ,vb.net course 5-15 Memory processing of image processing 6 Just change a parameter

import：

Imports System.Drawing
Imports System.Drawing.Imaging
Imports System.Runtime.InteropServices

Write function ：value You can adjust yourself , Not necessarily just 180

 ''' <summary>
    '''  Black and white processing of pictures , Remember to use multithreading to call functions 
    ''' </summary>
    ''' <param name="value"> Black and white numerical constants , Recommend from 128 Start adjusting , The scope is 0~255(byte)</param>
    ''' <param name="bmp"> The image to be processed </param>
    ''' <returns> Processed pictures </returns>

    Public Function BlackWhite(value As Byte, bmp As Bitmap)
        Dim destImg As New Bitmap(bmp.Width, bmp.Height)
        Dim sourceData As BitmapData = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb)
        Dim destData As BitmapData = destImg.LockBits(New Rectangle(0, 0, bmp.Width, bmp.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 >= value Then avgValue = 255 Else avgValue = 0
                rgbvalues(pos) = avgValue
                rgbvalues(pos + 1) = avgValue
                rgbvalues(pos + 2) = avgValue
                pos += 3
            Next
            pos = pos + sourceData.Stride - sourceData.Width * 3
        Next
        Dim pDest As IntPtr = destData.Scan0
        Marshal.Copy(rgbvalues, 0, pDest, allBytes)

        bmp.UnlockBits(sourceData)
        destImg.UnlockBits(destData)

        Return destImg

    End Function

  call ：

 Private Sub Button6_Click(sender As Object, e As EventArgs) Handles Button6.Click
        Pic.Image = GDI.BlackWhite(180, New Bitmap("C:\Users\Administrator\Desktop\example.jpg"))
    End Sub

The effect is very good , Some wrinkles can be removed , Redundant background