How to change src of img in html file

I have a page using which a user can upload a html file in his account to send it as a mailer to others. I need help to detect images on html file and replace the src of each to absolute path. I have regex to detect the img tab but not able to detect src value

Filename = "albmailer.html" ' file to read
Const ForReading = 1, ForWriting = 2, ForAppending = 3
Const TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0

' Create a filesystem object
Dim FSO
set FSO = server.createObject("Scripting.FileSystemObject")

' Map the logical path to the physical system path
Dim Filepath
Filepath = Server.MapPath(Filename)

if FSO.FileExists(Filepath) Then

' Get a handle to the file
Dim file
set file = FSO.GetFile(Filepath)

' Get some info about the file
Dim FileSize
FileSize = file.Size

Response.Write "<p><b>File: " & Filename & " (size " & FileSize &_
" bytes)</b></p><hr>"
Response.Write "<pre>"

' Open the file
Dim TextStream
Set TextStream = file.OpenAsTextStream(ForReading, TristateUseDefault)

' Read the file line by line
Do While Not TextStream.AtEndOfStream
Dim Line
Line = TextStream.readline

' Do something with "Line"
Line = Line & vbCRLF

'Response.write Line
sOutput = sOutput&Line
Loop


'Response.Write "</pre><hr>"

Set TextStream = nothing

Else

Response.Write "<h3><i><font color=red> File " & Filename &_
" does not exist</font></i></h3>"

End If

Set FSO = nothing


sPattern = "<img[^>]*>"
sPattern = "\<img\s[^\>]*?src=[""']([^""']*?\.(jpg|jpeg|bmp|gif|png)(\?[^""']*)?)[""'][^\>]*\>"
set objReg = new regexp
objReg.Pattern = sPattern
objReg.IgnoreCase = true
objReg.Global = true
set sMatch = objReg.Execute(sOutput)
for each match in sMatch
response.Write(match&"<br>")
next

%>

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