如何转换图像 [英] How to I convert image

问题描述

我没有一点长的错误我知道



我尝试过：

i dont some lenth error i dint understood

What I have tried:

Imports System.IO
Imports System.Text

Public Class Form1
    Dim path As String = Directory.GetCurrentDirectory()
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        ''First i choose a img to convert to byte 
        Dim img As Image = Image.FromFile("C:\Users\admin\Desktop\1550157567366_1-xlg400x400.jpg")
        ''Second i convertexd the image to byte 
        Dim bArr As Byte() = imgToByteArray(img)
        ''third i converted byte to string 
        Dim istring As String = Bytes_To_String2(bArr)
        'just exported to a text file in same path folder 
        '----------------------------------
        ExportTextFile(istring)
        ' Dim bArr2 As Byte() = stringToByteArray(istring)
        '----------------------------------
        'Step four back to back from string to byte
        Dim bArr2 As Byte() = ToByteArray(istring)
        'step five bytes to img last stage is confusion 
        Dim img1 As Image = byteArrayToImage(bArr2)
        'dint no see any picture in the picturebox1
        PictureBox1.Image = img1
    End Sub
    Public Function imgToByteArray(ByVal img As Image) As Byte()
        'Fisrt step
        Using mStream As New MemoryStream()
            img.Save(mStream, img.RawFormat)
            Return mStream.ToArray()
        End Using
    End Function
    Private Function Bytes_To_String2(ByVal bytes_Input As Byte()) As String
        'Second Step  conversion of byte to sring
        Dim strTemp As New StringBuilder(bytes_Input.Length * 2)
        For Each b As Byte In bytes_Input
            strTemp.Append(Conversion.Hex(b))
        Next
        MsgBox(strTemp.ToString())
        Return strTemp.ToString()
    End Function
    Sub ExportTextFile(ByVal revokedlinks As String)
        'thrid Step Convesion of string to text file 
        Dim RevokedTextFile As String = path & "\StringToTextFile.txt"
        If File.Exists(RevokedTextFile) = True Then
            Dim appendText As String = revokedlinks
            File.AppendAllText(RevokedTextFile, appendText)
            Dim readText As String = File.ReadAllText(RevokedTextFile)
        End If
        If File.Exists(RevokedTextFile) = False Then
            Dim createText As String = revokedlinks
            File.WriteAllText(RevokedTextFile, createText)
        End If
    End Sub
    Public Function ToByteArray(ByVal someString As String) As Byte()
        'step four
        Dim byteList As New List(Of Byte)
        Try
            Dim tempString As String = someString.Replace("&H", "")
            If tempString.Length Mod 2 = 1 Then tempString = "0" & tempString

            For index As Integer = 0 To tempString.Length Step 2
                byteList.Add(Convert.ToByte(Val("&H" & tempString.Substring(index, 2))))
            Next
        Catch ex As Exception
            MessageBox.Show(ex.ToString)
        End Try
        Return byteList.ToArray
    End Function
    'convert bytearray to image
    Public Function byteArrayToImage(ByVal byteArrayIn As Byte()) As Image
        'step 5 dint work 
        Using mStream As New MemoryStream(byteArrayIn)
            Return Image.FromStream(mStream)
        End Using
    End Function


End Class

推荐答案

dint work不是一个有用的错误报告，甚至没有一点点。

但这种方法不起作用。

问题 - 或者至少其中一个问题 - 是Conversion.Hex没有返回相同数量的数字每次x值：如果值低于16，则返回一位数，如果它在上面则返回两位 - 你无法告诉你的 ToByteArray 方法。因此，如果您有两个4彼此相邻，则将其作为单个字节44处理，这意味着您从文件中读回的数据长度与原始数据不同。



零重要！



而不是像这样做 - 这根本不是一个好的解决方案 - 考虑使用Base64数据存储您的图像 - 它是文本，但比您的文本更紧凑，并且它不像您那样丢弃数据。

"dint work" is not a helpful error report, not even slightly.
But that approach will not work.
The problem - or at least one of the problems - is that Conversion.Hex does not return the same number of digits of hex value each time: if the value is below 16, it returns one digit, if it's above it returns two - and you can't tell in your ToByteArray method which it was. So if you have two "4"s next to each other, you will process it as a single byte "44" which means that the length of the data you read back from your file is not the same as the original.

Zeros are important!

Instead of faffing about like this - which isn't a good solution at all - consider using Base64 data to store your you image - it's text, but more compact than yours, and it doesn't discard data like yours does.

如何转换回图像？

How to convert back to image ?

Imports System.IO

Public Class Form1
    Dim path As String = Directory.GetCurrentDirectory()
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        'Dim img As Image = Image.FromFile("C:\Users\admin\Desktop\1550157567366_1-xlg400x400.jpg")
        Dim istring As String = ConvertFileToBase64("C:\Users\admin\Desktop\1550157567366_1-xlg400x400.jpg")
        ExportTextFile(istring)

    End Sub
    Public Function ConvertFileToBase64(ByVal fileName As String) As String
        Dim ReturnValue As String = ""
        If My.Computer.FileSystem.FileExists(fileName) Then
            Using BinaryFile As FileStream = New FileStream(fileName, FileMode.Open)
                Dim BinRead As BinaryReader = New BinaryReader(BinaryFile)
                Dim BinBytes As Byte() = BinRead.ReadBytes(CInt(BinaryFile.Length))
                ReturnValue = Convert.ToBase64String(BinBytes)
                BinaryFile.Close()
            End Using
        End If
        Return ReturnValue
    End Function
    Sub ExportTextFile(ByVal revokedlinks As String)
        'thrid Step Convesion of string to text file 
        Dim RevokedTextFile As String = Path & "\StringToTextFile.txt"
        If File.Exists(RevokedTextFile) = True Then
            Dim appendText As String = revokedlinks
            File.AppendAllText(RevokedTextFile, appendText)
            Dim readText As String = File.ReadAllText(RevokedTextFile)
        End If
        If File.Exists(RevokedTextFile) = False Then
            Dim createText As String = revokedlinks
            File.WriteAllText(RevokedTextFile, createText)
        End If
    End Sub
End Class

最后它工作

finally it work

Imports System.IO

Public Class Form1
    Dim path As String = Directory.GetCurrentDirectory()
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        'Dim img As Image = Image.FromFile("C:\Users\admin\Desktop\1550157567366_1-xlg400x400.jpg")
        Dim istring As String = ConvertFileToBase64("C:\Users\admin\Desktop\1550157567366_1-xlg400x400.jpg")
        ExportTextFile(istring)
        Dim b As Byte() = Convert.FromBase64String(istring)
        Dim img1 As Image = byteArrayToImage(b)
        PictureBox1.Image = img1
    End Sub
    Public Function byteArrayToImage(ByVal byteArrayIn As Byte()) As Image
        'step 5 dint work 
        Using mStream As New MemoryStream(byteArrayIn)
            Return Image.FromStream(mStream)
        End Using
    End Function

    Public Function ConvertFileToBase64(ByVal fileName As String) As String
        Dim ReturnValue As String = ""
        If My.Computer.FileSystem.FileExists(fileName) Then
            Using BinaryFile As FileStream = New FileStream(fileName, FileMode.Open)
                Dim BinRead As BinaryReader = New BinaryReader(BinaryFile)
                Dim BinBytes As Byte() = BinRead.ReadBytes(CInt(BinaryFile.Length))
                ReturnValue = Convert.ToBase64String(BinBytes)
                BinaryFile.Close()
            End Using
        End If
        Return ReturnValue
    End Function

    Sub ExportTextFile(ByVal revokedlinks As String)
        'thrid Step Convesion of string to text file 
        Dim RevokedTextFile As String = Path & "\StringToTextFile.txt"
        If File.Exists(RevokedTextFile) = True Then
            Dim appendText As String = revokedlinks
            File.AppendAllText(RevokedTextFile, appendText)
            Dim readText As String = File.ReadAllText(RevokedTextFile)
        End If
        If File.Exists(RevokedTextFile) = False Then
            Dim createText As String = revokedlinks
            File.WriteAllText(RevokedTextFile, createText)
        End If
    End Sub
End Class

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