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STEP 1: SAVE THE FOLLOWING CODE AS cAspImage.asp:
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<%
'============================================================
' MODULE:   cAspImage.asp
' AUTHOR:   © www.u229.no
' CREATED:  May 2005
'============================================================
' COMMENT:
' Read Image Properties from BMP, GIF, PNG and JPG files.
' Requirements: Microsoft Data Access Components installed on Web Server.

'  PLEASE NOTE: Some JPEG files contain Thumbnails. In those cases this code will fail because
' it will think that the thumbnail's width/height are the "real" values.
' If this is a concern see more info on line 151.
'============================================================
' TODO:
'============================================================
' ROUTINES:
' - Private Sub Class_Initialize()
' - Private Sub Class_Terminate()
' - Public Function ReadImage(sFullPath)
' - Private Function ReadByteArray(sFullPath)
' - Private Sub EmptyVariables()
'============================================================


Class cAspImage

'// MODULE VARIABLES
Private m_arrBytes                '// Byte array holding the image file
Private m_lWidth                   '// Width in pixels
Private m_lHeight                  '// Height in pixels
Private m_iColorDepth           '// Color Depth (BitsPerPixel)
Private m_lImageSize            '// # Bytes in image
Private m_sDateCreated        '// Date Created
Private m_sLastModified         '// Date last saved
Private m_sImageType          '// PNG, JPG, GIF87a/GIF89a, BMP
Private m_sErrorMsg              '// Error message: Check this if ReadImage returns false

'// PROPERTIES
Public Property Get Width()
    Width = m_lWidth
End Property
Public Property Get Height()
    Height = m_lHeight
End Property
Public Property Get ColorDepth()
    ColorDepth = m_iColorDepth
End Property
Public Property Get ImageSize()
    ImageSize = m_lImageSize
End Property
Public Property Get DateCreated()
    DateCreated = m_sDateCreated
End Property
Public Property Get DateLastModified()
    DateLastModified = m_sLastModified
End Property
Public Property Get ImageType()
    ImageType = m_sImageType
End Property
Public Property Get ErrorMessage()
    ErrorMessage = m_sErrorMsg
End Property

'------------------------------------------------------------------------------------------------------------
' Comment: Init module variables.
'------------------------------------------------------------------------------------------------------------
Private Sub Class_Initialize()
    On Error Resume Next

    Call EmptyVariables

End Sub

'------------------------------------------------------------------------------------------------------------
' Comment: Clean up.
'------------------------------------------------------------------------------------------------------------
Private Sub Class_Terminate()
End Sub

'------------------------------------------------------------------------------------------------------------
' Comment: Main routine returning the image properties.
'------------------------------------------------------------------------------------------------------------
Public Function ReadImage(sFullPath)
'    On Error Resume Next

    Dim oFSO
    Dim oFile
    Dim i
    Dim bStop
	Dim lTmpHeight
	Dim lTmpWidth
	Dim iTmpDepth

    '// These 3 are created to speed up the looping.
    Dim i4
    Dim byteTmp
    Dim lSafeSize

    Call EmptyVariables

    bStop = False

    If IsEmpty(oFSO) Then Set oFSO = Server.CreateObject("Scripting.FileSystemObject")

    If oFSO.FileExists(sFullPath) Then

        Set oFile = oFSO.GetFile(sFullPath)

        m_lImageSize = oFile.Size
        m_sDateCreated = FormatDateTime(oFile.DateCreated, 2)
        m_sLastModified = FormatDateTime(oFile.DateLastModified, 2)

        If Not ReadByteArray(sFullPath) Then m_sErrorMsg = "Error Reading Image File"

'---------------------------- GIF
        If AscB(MidB(m_arrBytes, 1, 1)) = 71 And AscB(MidB(m_arrBytes, 2, 1)) = 73 And AscB(MidB( _
                        m_arrBytes, 3, 1)) = 70 Then

            m_sImageType = "GIF89a"

            If AscB(MidB(m_arrBytes, 5, 1)) = 55 Then m_sImageType = "GIF87a"

            m_lWidth = CLng(AscB(MidB(m_arrBytes, 7, 1)) + (AscB(MidB(m_arrBytes, 8, 1)) * 256))
            m_lHeight = CLng(AscB(MidB(m_arrBytes, 9, 1)) + (AscB(MidB(m_arrBytes, 10, 1)) * 256))
            m_iColorDepth = 2 ^ ((Asc(CStr(AscB(MidB(m_arrBytes, 11, 1)))) And 7) + 1)

            bStop = True

        End If

'---------------------------- JPG

		If Not bStop Then
			If AscB(MidB(m_arrBytes, 1, 1)) = 255 And AscB(MidB(m_arrBytes, 2, 1)) = 216 And AscB(MidB( _
							m_arrBytes, 3, 1)) = 255 And AscB(MidB(m_arrBytes, 4, 1)) = 224 Then

				m_sImageType = "JPG"
				lSafeSize = (m_lImageSize - 1)

				For i = 5 To lSafeSize

					If AscB(MidB(m_arrBytes, i, 1)) = 255 Then

						byteTmp = AscB(MidB(m_arrBytes, i + 1, 1))

						If (byteTmp > 191) And (byteTmp < 208) Then
						
						    i4 = AscB(MidB(m_arrBytes, i + 4, 1))

'=============================================================================================
'// Some JPEG files contain Thumbnails. In those cases this code will fail because it will think that the thumbnail's width/height are the "real" values.
'// If you care about the "thumbnail problem" you may comment existing code/uncomment the other lines below.
'// Be aware that this will dramatically slow down the looping time because we then will have to loop through the whole file(s)

							m_lHeight = CLng(AscB(MidB(m_arrBytes, i + 6, 1)) + (AscB(MidB(m_arrBytes, i + 5, 1)) * 256))
							m_lWidth = CLng(AscB(MidB(m_arrBytes, i + 8, 1)) + (AscB(MidB(m_arrBytes, i + 7, 1)) * 256))
							m_iColorDepth = CInt(i4) * CInt(AscB(MidB(m_arrBytes, i + 9, 1)))

'							lTmpHeight = CLng(AscB(MidB(m_arrBytes, i + 6, 1)) + (AscB(MidB(m_arrBytes, i + 5, 1)) * 256))
'							lTmpWidth = CLng(AscB(MidB(m_arrBytes, i + 8, 1)) + (AscB(MidB(m_arrBytes, i + 7, 1)) * 256))
'							iTmpDepth = CInt(i4) * CInt(AscB(MidB(m_arrBytes, i + 9, 1)))
'
							If m_iColorDepth > 0 And (i4 > 1 And i4 < 17) Then
'							If iTmpDepth > 0 And (i4 > 1 And i4 < 17) Then
'								If (lTmpHeight > m_lHeight) Or (lTmpWidth > m_lWidth) Then
'									m_lHeight = lTmpHeight
'									m_lWidth = lTmpWidth
'									m_iColorDepth = iTmpDepth
                                                                        Exit For
'								End If
							End If
'=============================================================================================
						End If
					End If

				Next

				bStop = True

			End If
		End If

'---------------------------- PNG
        If Not bStop Then
            If AscB(MidB(m_arrBytes, 1, 1)) = 137 And AscB(MidB(m_arrBytes, 2, 1)) = 80 And AscB( _
                            MidB(m_arrBytes, 3, 1)) = 78 And AscB(MidB(m_arrBytes, 4, 1)) = 71 _
                            And AscB(MidB(m_arrBytes, 5, 1)) = 13 And AscB(MidB(m_arrBytes, 6, _
                            1)) = 10 And AscB(MidB(m_arrBytes, 7, 1)) = 26 And AscB(MidB(m_arrBytes, 8, 1)) = 10 Then

                m_sImageType = "PNG"
                m_lWidth = CLng(AscB(MidB(m_arrBytes, 20, 1)) + (AscB(MidB(m_arrBytes, 19, 1)) * 256))
                m_lHeight = CLng(AscB(MidB(m_arrBytes, 24, 1)) + (AscB(MidB(m_arrBytes, 23, 1)) * 256))

                Select Case CInt(AscB(MidB(m_arrBytes, 26, 1)))                                  '// Get Bit Depth

                    Case 0
                        m_iColorDepth = CInt(AscB(MidB(m_arrBytes, 25, 1)))                  '// Grayscale
                        
                    Case 2
                        m_iColorDepth = CInt(AscB(MidB(m_arrBytes, 25, 1))) * 3            '// RGB encoded
                        
                    Case 3
                        m_iColorDepth = 8                                                                     '// Palette based, 8 bpp
                        
                       Case 4
                        m_iColorDepth = CInt(AscB(MidB(m_arrBytes, 25, 1))) * 2            '// greyscale with alpha
                        
                    Case 6
                        m_iColorDepth = CInt(AscB(MidB(m_arrBytes, 25, 1))) * 4            '// RGB encoded with alpha
                        
                    Case Else
                End Select

                bStop = True

            End If
        End If

'---------------------------- BMP
        If Not bStop Then
            If AscB(MidB(m_arrBytes, 1, 1)) = 66 And AscB(MidB(m_arrBytes, 2, 1)) = 77 Then

                m_sImageType = "BMP"
                m_lWidth = CLng(AscB(MidB(m_arrBytes, 19, 1)) + (AscB(MidB(m_arrBytes, 20, 1)) * 256))
                m_lHeight = CLng(AscB(MidB(m_arrBytes, 23, 1)) + (AscB(MidB(m_arrBytes, 24, 1)) * 256))
                m_iColorDepth = CInt(AscB(MidB(m_arrBytes, 29, 1)))

                bStop = True

            End If
        End If

'----------------------------

    Else
        m_sErrorMsg = "Error in File Path: " & sFullPath
    End If
    
    Set oFile = Nothing
    Set oFSO = Nothing

    ReadImage = (Err.Number = 0)

End Function

'------------------------------------------------------------------------------------------------------------
' Comment: Read image into byte array.
'------------------------------------------------------------------------------------------------------------
Private Function ReadByteArray(sFullPath)
    On Error Resume Next

    Dim oStream

    If IsEmpty(oStream) Then Set oStream = Server.CreateObject("ADODB.Stream")

    With oStream
        .Type = 1                     '// adTypeBinary
        .Open
        .LoadFromFile sFullPath
        m_arrBytes = .Read
    End With

    oStream.Close
    Set oStream = Nothing

    ReadByteArray = (Err.Number = 0)

End Function

'------------------------------------------------------------------------------------------------------------
' Comment: Set module variables empty.
'------------------------------------------------------------------------------------------------------------
Private Sub EmptyVariables()
    On Error Resume Next

    m_lWidth = 0
    m_lHeight = 0
    m_iColorDepth = 0
    m_lImageSize = 0
    m_sDateCreated = ""
    m_sLastModified = ""
    m_sImageType = "Unknown"
    m_sErrorMsg = ""

End Sub


End Class

%>


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STEP 2: SAVE THE FOLLOWING AS start.asp IN THE SAME FOLDER AS ABOVE.
ALSO PUT A GIF FILE INTO THE SAME FOLDER AND NAME IT test.gif.
THEN POINT YOUR BROWSER TO start.asp.
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<% @Language="VBScript" %>
<%
Option Explicit
'On Error Resume Next
%>
<!--#include file="cAspImage.asp"-->
<%
'// HOW TO USE THIS CODE:

Dim oAspImg

Set oAspImg = New cAspImage

With oAspImg
    .ReadImage(Server.MapPath("test.gif"))
	Response.Write "ImageSize: " & .ImageSize & "<br />"
	Response.Write "Date Created: " & .DateCreated & "<br />"
	Response.Write "Date Last Modified: " & .DateLastModified & "<br />"
	Response.Write "ColorDepth: " & .ColorDepth & "<br />"
	Response.Write "Width: " & .Width & "<br />"
	Response.Write "Height: " & .Height & "<br />"
	Response.Write "ImageType: " & .ImageType & "<br />"
	Response.Write "Error Message: " & .ErrorMessage & "<br />"
End With

Set oAspImg = Nothing

%>