Image turns out all strange, and I can't find what's wrong

I'm making my own new image format where any pixel with an alpha less than a specific amount is dropped, and up to 255 colors are stored in a dictionary for additional compression. The format is like this:

Not one of the 255 colors in the dictionary: Argb representation
In dictionary: 0 for the alpha byte, number of repetitions in the R and G bytes, and index in the B byte.

Each group is stored like so:
0 x y colors.

I'm getting an IndexOutOfRangeException because the dictionary never has anything in it, and I can't figure out why. I have no idea what's going wrong! Here's my code:

vb.net Code:

Imports System.IO
Imports System.Runtime.InteropServices
Imports System.Drawing.Imaging
Public NotInheritable Class EACImage
 
    Public Shared Sub FromBitmap(ByVal b As Bitmap, ByVal output As String, Optional ByVal threshold As Integer = 0)
        Dim r As New Rectangle(0, 0, b.Width, b.Height)
        Using fs As New FileStream(output, FileMode.Create, FileAccess.Write)
            Using bw As New BinaryWriter(fs)
                Dim bd As BitmapData = b.LockBits(r, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb)
                Dim arr(bd.Width * bd.Height - 1) As Integer
                Marshal.Copy(bd.Scan0, arr, 0, arr.Length)
 
                'Prepare information
                Dim dictionary As New List(Of Integer)
                Dim data As New List(Of Integer)
                For i As Integer = 0 To arr.Length - 1
                    While GetAComp(arr(i)) <= threshold
                        i += 1
                        If i = arr.Length Then Exit For
                    End While
                    data.Add(0) 'Begin a new group
                    data.Add(i Mod bd.Width) 'Width
                    data.Add(i \ bd.Width) 'Height
                    While (i < arr.Length) AndAlso (GetAComp(arr(i)) > threshold)
                        data.Add(arr(i))
                        i += 1
                    End While
                Next
 
                'Compress the list
                CompressList(data, dictionary)
 
                'Write header information
                For Each item As Integer In dictionary
                    bw.Write(item)
                    MsgBox("Wrote " & item)
                Next
                bw.Write(0I)
                bw.Write(bd.Width)
                bw.Write(bd.Height)
 
                'Write data
                For Each item As Integer In data
                    bw.Write(item)
                Next
 
                'Unlock the bitmap
                b.UnlockBits(bd)
 
                'Close the streams.
                bw.Close()
                fs.Close()
            End Using
        End Using
    End Sub
 
    Public Shared Function FromFile(ByVal f As String) As Bitmap
        Dim r As Bitmap = Nothing
 
        Using fs As New FileStream(f, FileMode.Open, FileAccess.Read)
            Using br As New BinaryReader(fs)
                Dim dict As New List(Of Integer)
                Do
                    Dim itm As Integer = br.ReadInt32()
                    If itm = 0 Then Exit Do
                    dict.Add(itm)
                Loop
                r = New Bitmap(br.ReadInt32(), br.ReadInt32(), PixelFormat.Format32bppArgb)
                Dim bd As BitmapData = r.LockBits(New Rectangle(0, 0, r.Width, r.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
                Dim arr(bd.Width * bd.Height - 1) As Integer
                Dim x As Integer = 0, y As Integer = 0
                Do
                    If br.BaseStream.Position = br.BaseStream.Length Then Exit Do
                    Dim n_int As Integer = br.ReadInt32()
                    If n_int = 0 Then 'next group
                        x = br.ReadInt32()
                        y = br.ReadInt32()
                    End If
                    If GetAComp(n_int) = 0 Then 'It's compressed
                        For j As Integer = 1 To GetRepetition(n_int)
                            arr(y * bd.Width + x) = dict(GetIndex(n_int))
                            x += 1
                            If x >= bd.Width Then
                                y += 1
                                x = x Mod bd.Width
                            End If
                        Next
                    Else 'Not compressed
                        arr(y * bd.Width + x) = n_int
                    End If
                    x += 1
                    If x >= bd.Width Then
                        y += 1
                        x = x Mod bd.Width
                    End If
                Loop
 
                'Copy back and unlock
                Marshal.Copy(arr, 0, bd.Scan0, arr.Length)
                r.UnlockBits(bd)
 
                'Close the streams.
                br.Close()
                fs.Close()
            End Using
        End Using
 
        Return r
    End Function
 
#Region "GetXXX"
    Friend Shared Function GetAComp(ByVal i As Integer) As Integer
        Dim sh24 As Integer = 255I << 24
        Dim res As Integer = i And sh24
        Return res >> 24
    End Function
 
    Friend Shared Function GetRepetition(ByVal i As Integer) As Integer
        Dim sh16 As Integer = 255 << 16
        Dim sh8 As Integer = 255 << 8
        Dim res As Integer = i And (sh16 Or sh8)
        Return res >> 8
    End Function
 
    Friend Shared Function GetIndex(ByVal i As Integer) As Integer
        Return (i And 255)
    End Function
 
    Friend Shared Function GetInt(ByVal count As Integer, ByVal index As Integer) As Integer
        If count > Short.MaxValue OrElse index > 255 Then Throw New ArgumentException()
        Return index Or (count << 8)
    End Function
#End Region
 
 
    Private Shared Sub CompressList(ByRef l As List(Of Integer), ByRef dict As List(Of Integer), Optional ByVal minrep As Integer = 30)
        dict.Clear()
        Dim nl As New List(Of Integer)
        Dim l_itm As Integer = -1
        Dim count As Integer = 0
        For i As Integer = 0 To l.Count - 1
            Dim itm As Integer = l(i)
            If itm = 0 Then
                i += 2
                If i >= l.Count Then Exit For
                itm = l(i)
            End If
            If count = 0 Then
                count = 1
                l_itm = itm
            Else
                If l_itm = itm Then
                    count += 1
                    If (count < UInt16.MaxValue) AndAlso (dict.Count < 255) Then Continue For
                End If
                If count <= minrep Then
                    nl.Add(itm)
                Else
                    Dim idx As Integer = dict.Count
                    If Not dict.Contains(itm) Then
                        dict.Add(itm)
                    Else
                        idx = dict.IndexOf(itm)
                    End If
                    nl.Add(GetInt(count, idx))
                End If
                l_itm = itm
                count = 1
            End If
        Next
        l = nl
    End Sub
 
End Class

Which line is giving the exception?

Sorry, I fixed that just now, I made a stupid mistake...

Right now, my problem is this:
Only the picture's outline shows. That's great for special effects, but not so good for what I want. Here's the code, and "before & after" pictures:

vb.net Code:

Imports System.IO
Imports System.Runtime.InteropServices
Imports System.Drawing.Imaging
Public NotInheritable Class EACImage
 
#Region "FromBitmap"
    Public Shared Sub FromBitmap(ByVal b As Bitmap, ByVal output As String, Optional ByVal threshold As Integer = 0)
        Dim r As New Rectangle(0, 0, b.Width, b.Height)
        Using fs As New FileStream(output, FileMode.Create, FileAccess.Write)
            Using bw As New BinaryWriter(fs)
                Dim bd As BitmapData = b.LockBits(r, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb)
                Dim arr(bd.Width * bd.Height - 1) As Integer
                Marshal.Copy(bd.Scan0, arr, 0, arr.Length)
 
                'Prepare information
                Dim dictionary As New List(Of Integer)
                Dim data As New List(Of Integer)
                For i As Integer = 0 To arr.Length - 1
                    data.Add(0) 'Begin a new group
                    Dim x As Integer = i Mod bd.Width
                    Dim y As Integer = i \ bd.Width
                    Debug.WriteLine("Adding at " & x & "," & y & "...")
                    data.Add(x)
                    data.Add(y)
 
                    While GetAComp(arr(i)) <= threshold
                        i += 1
                        If i = arr.Length Then Exit For
                    End While
                    While (i < arr.Length) AndAlso (GetAComp(arr(i)) > threshold)
                        data.Add(arr(i))
                        i += 1
                    End While
                Next
 
                'Compress the list
                CompressList(data, dictionary)
 
                'Write header information
                For Each item As Integer In dictionary
                    bw.Write(item)
                Next
                bw.Write(0I)
                bw.Write(bd.Width)
                bw.Write(bd.Height)
 
                'Write data
                For Each item As Integer In data
                    bw.Write(item)
                Next
 
                'Unlock the bitmap
                b.UnlockBits(bd)
 
                'Close the streams.
                bw.Close()
                fs.Close()
            End Using
        End Using
    End Sub
#End Region
 
#Region "FromFile"
    Public Shared Function FromFile(ByVal f As String) As Bitmap
        Dim r As Bitmap = Nothing
 
        Using fs As New FileStream(f, FileMode.Open, FileAccess.Read)
            Using br As New BinaryReader(fs)
                Dim dict As New List(Of Integer)
                Do
                    Dim itm As Integer = br.ReadInt32()
                    If itm = 0 Then Exit Do
                    dict.Add(itm)
                Loop
                r = New Bitmap(br.ReadInt32(), br.ReadInt32(), PixelFormat.Format32bppArgb)
                Dim bd As BitmapData = r.LockBits(New Rectangle(0, 0, r.Width, r.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
                Dim arr(bd.Width * bd.Height - 1) As Integer
                Dim i As Integer = 0
                Do
                    If br.BaseStream.Position = br.BaseStream.Length Then Exit Do
                    Dim n_int As Integer = br.ReadInt32()
                    If n_int = 0 Then 'next group
                        Dim x As Integer = br.ReadInt32()
                        Dim y As Integer = br.ReadInt32()
                        Debug.WriteLine("Recieved coordinates " & x & "," & y & ".")
                        i = (y * bd.Width) + x
                        Continue Do
                    End If
                    If GetAComp(n_int) = 0 Then 'It's compressed
                        Dim index As Integer = GetIndex(n_int)
                        For j As Integer = 1 To GetRepetition(n_int)
                            arr(i) = dict(index)
                            i += 1
                        Next
                    Else 'Not compressed
                        Debug.WriteLine("Current X is " & (i Mod bd.Width).ToString())
                        Debug.WriteLine("Current Y is " & (i \ bd.Width).ToString())
                        arr(i) = n_int
                    End If
                    i += 1
                Loop
 
                'Copy back and unlock
                Marshal.Copy(arr, 0, bd.Scan0, arr.Length)
                r.UnlockBits(bd)
 
                'Close the streams.
                br.Close()
                fs.Close()
            End Using
        End Using
 
        Return r
    End Function
#End Region
 
#Region "GetXXX"
    Friend Shared Function GetAComp(ByVal i As Integer) As Integer
        Dim sh24 As Integer = 255I << 24
        Dim res As Integer = i And sh24
        Return res >> 24
    End Function
 
    Friend Shared Function GetRepetition(ByVal i As Integer) As Integer
        'Dim sh16 As Integer = 255 << 16
        'Dim sh8 As Integer = 255 << 8
        'Dim res As Integer = i And (sh16 Or sh8)
        'Return res >> 8
        Return (i Xor 255) >> 8
    End Function
 
    Friend Shared Function GetIndex(ByVal i As Integer) As Integer
        Return (i And 255)
    End Function
 
    Friend Shared Function GetInt(ByVal count As Integer, ByVal index As Integer) As Integer
        If count > Short.MaxValue OrElse index > 255 Then Throw New ArgumentException()
        Return index Or (count << 8)
    End Function
#End Region
 
#Region "CompressList"
    ''' <summary>
    ''' Compresses a list of colors representing the first stage of an EAC image.
    ''' </summary>
    ''' <param name="l">The list of colors.</param>
    ''' <param name="dict">The dictionary.</param>
    ''' <param name="minrep">The minimum amount of repetitions.</param>
    Private Shared Sub CompressList(ByRef l As List(Of Integer), ByRef dict As List(Of Integer), Optional ByVal minrep As Integer = 30)
        dict.Clear()
        Dim nl As New List(Of Integer)
        Dim l_itm As Integer = -1
        Dim count As Integer = 0
        For i As Integer = 0 To l.Count - 1
            Dim itm As Integer = l(i)
            If itm = 0 Then
                nl.Add(l(i))
                nl.Add(l(i + 1))
                nl.Add(l(i + 2))
                i += 2
                Continue For
            End If
            If count = 0 Then
                count = 1
                l_itm = itm
            Else
                If l_itm = itm Then
                    count += 1
                    If (count < UInt16.MaxValue) AndAlso (dict.Count < 255) Then Continue For
                End If
                If count <= minrep Then
                    nl.Add(itm)
                Else
                    Dim idx As Integer = dict.IndexOf(itm)
                    If idx = -1 Then
                        dict.Add(itm)
                        idx = dict.Count - 1
                    End If
                    nl.Add(GetInt(count, idx))
                End If
                l_itm = itm
                count = 1
            End If
        Next
        l = nl
    End Sub
#End Region
 
End Class

Looks like you are not decompressing correctly. It looks like you are getting the first and last bits, but the internal bits are being lost.

Yup. I think the information is being stored properly, because of the size of the EAC file. Do you know why? At first, I thought it was because of the CompressList method, so I commented the body out (if you do that, it just doesn't compress)... no change.

Ok, I've added to my code, changed some things, and added debugging statements. It seems that the file isn't being written to correctly. Here's my code, and the log file is attached:

vb.net Code:

Imports System.IO
Imports System.Runtime.InteropServices
Imports System.Drawing.Imaging
Public NotInheritable Class EACImage
 
#Region "Log Debugger"
#If CONFIG = "Debug" Then
    Private Shared Debug As Debugger
 
    Private Class Debugger
        Implements IDisposable
 
        Private m_InnerStream As StreamWriter
        Public Sub New()
            m_InnerStream = New StreamWriter("debug_log.txt")
        End Sub
        Public Sub WriteLine(ByVal ln As String)
            m_InnerStream.WriteLine(ln)
        End Sub
        Private disposedValue As Boolean = False
        Protected Overridable Sub Dispose(ByVal disposing As Boolean)
            If Not Me.disposedValue Then
                If disposing Then
                    m_InnerStream.Close()
                    m_InnerStream.Dispose()
                    m_InnerStream = Nothing
                End If
            End If
            Me.disposedValue = True
        End Sub
        Public Sub Dispose() Implements IDisposable.Dispose
            Dispose(True)
            GC.SuppressFinalize(Me)
        End Sub
 
        Protected Overrides Sub Finalize()
            Me.Dispose(False)
            MyBase.Finalize()
        End Sub
    End Class
#End If
#End Region
 
#Region "FromBitmap"
    Public Shared Sub FromBitmap(ByVal b As Bitmap, ByVal output As String, Optional ByVal threshold As Integer = 0)
#If CONFIG = "Debug" Then
        Debug = New Debugger()
#End If
        Dim r As New Rectangle(0, 0, b.Width, b.Height)
        Using fs As New FileStream(output, FileMode.Create, FileAccess.Write)
            Using bw As New BinaryWriter(fs)
                Dim bd As BitmapData = b.LockBits(r, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb)
                Dim arr(bd.Width * bd.Height - 1) As Integer
                Marshal.Copy(bd.Scan0, arr, 0, arr.Length)
 
                'Unlock the bitmap
                b.UnlockBits(bd)
 
                'Prepare information
                Dim dictionary As New List(Of Integer)
                Dim data As New List(Of Integer)
                For i As Integer = 0 To arr.Length - 1
                    While GetAComp(arr(i)) <= threshold
                        i += 1
                        If i = arr.Length Then Exit For
                    End While
 
                    'Begin a new group
                    data.Add(0I)
                    Dim x As Integer = i Mod bd.Width
                    Dim y As Integer = i \ bd.Width
                    data.Add(x)
                    data.Add(y)
 
                    While (i < arr.Length) AndAlso (GetAComp(arr(i)) > threshold)
                        data.Add(arr(i))
                        i += 1
                    End While
                Next
 
                'Compress the list
                'CompressList(data, dictionary, 30)
 
                'Write header information
                For Each item As Integer In dictionary
                    bw.Write(item)
                Next
                bw.Write(0I)
                bw.Write(bd.Width)
                bw.Write(bd.Height)
 
                'Write data
                For Each item As Integer In data
                    bw.Write(item)
                Next
 
                'Close the streams.
                bw.Close()
                fs.Close()
            End Using
        End Using
#If CONFIG = "Debug" Then
        Debug.Dispose()
        Debug = Nothing
#End If
    End Sub
#End Region
 
#Region "FromFile"
    Public Shared Function FromFile(ByVal f As String) As Bitmap
#If CONFIG = "Debug" Then
        Debug = New Debugger()
#End If
        Dim r As Bitmap = Nothing
 
        Using fs As New FileStream(f, FileMode.Open, FileAccess.Read)
            Using br As New BinaryReader(fs)
                Dim dict As New List(Of Integer)
                Do
                    Dim itm As Integer = br.ReadInt32()
                    If itm = 0 Then Exit Do
                    dict.Add(itm)
                Loop
                r = New Bitmap(br.ReadInt32(), br.ReadInt32(), PixelFormat.Format32bppArgb)
                Dim bd As BitmapData = r.LockBits(New Rectangle(0, 0, r.Width, r.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
                Dim arr(bd.Width * bd.Height - 1) As Integer
                Dim i As Integer = 0
                Do
                    If br.BaseStream.Position = br.BaseStream.Length Then Exit Do
                    Dim n_int As Integer = br.ReadInt32()
                    If n_int = 0 Then 'next group
                        Dim x As Integer = br.ReadInt32()
                        Dim y As Integer = br.ReadInt32()
                        Debug.WriteLine("Recieved coordinates " & x & "," & y & ".")
                        i = (y * bd.Width) + x
                        Continue Do
                    End If
                    If GetAComp(n_int) = 0 Then 'It's compressed
                        Dim index As Integer = GetIndex(n_int)
                        For j As Integer = 1 To GetRepetition(n_int)
                            arr(i) = dict(index)
                            i += 1
                        Next
                    Else 'Not compressed
                        Debug.WriteLine("Current X is " & (i Mod bd.Width).ToString())
                        Debug.WriteLine("Current Y is " & (i \ bd.Width).ToString())
                        arr(i) = n_int
                    End If
                    i += 1
                Loop
 
                'Copy back and unlock
                Marshal.Copy(arr, 0, bd.Scan0, arr.Length)
                r.UnlockBits(bd)
 
                'Close the streams.
                br.Close()
                fs.Close()
            End Using
        End Using
#If CONFIG = "Debug" Then
        Debug.Dispose()
#End If
        Return r
    End Function
#End Region
 
#Region "GetXXX"
    Friend Shared Function GetAComp(ByVal i As Integer) As Integer
        Dim sh24 As Integer = 255I << 24
        Dim res As Integer = i And sh24
        Return res >> 24
    End Function
 
    Friend Shared Function GetRepetition(ByVal i As Integer) As Integer
        'Dim sh16 As Integer = 255 << 16
        'Dim sh8 As Integer = 255 << 8
        'Dim res As Integer = i And (sh16 Or sh8)
        'Return res >> 8
        Return (i Xor 255) >> 8
    End Function
 
    Friend Shared Function GetIndex(ByVal i As Integer) As Integer
        Return (i And 255)
    End Function
 
    Friend Shared Function GetInt(ByVal count As Integer, ByVal index As Integer) As Integer
        If count > Short.MaxValue OrElse index > 255 Then Throw New ArgumentException()
        Return index Or (count << 8)
    End Function
#End Region
 
#Region "CompressList"
    ''' <summary>
    ''' Compresses a list of colors representing the first stage of an EAC image.
    ''' </summary>
    ''' <param name="l">The list of colors.</param>
    ''' <param name="dict">The dictionary.</param>
    ''' <param name="minrep">The minimum amount of repetitions.</param>
    Private Shared Sub CompressList(ByRef l As List(Of Integer), ByRef dict As List(Of Integer), Optional ByVal minrep As Integer = 30)
        dict.Clear()
        Dim nl As New List(Of Integer)
        Dim l_itm As Integer = -1
        Dim count As Integer = 0
        For i As Integer = 0 To l.Count - 1
            Dim itm As Integer = l(i)
            If itm = 0 Then
                nl.Add(0I)
                nl.Add(l(i + 1))
                nl.Add(l(i + 2))
                i += 2
                Continue For 'Will also add 1 to i.
            End If
            If count = 0 Then
                count = 1
                l_itm = itm
            Else
                If l_itm = itm Then
                    count += 1
                    If (count < UInt16.MaxValue) AndAlso (dict.Count < 255) Then Continue For
                End If
                If count <= minrep Then
                    For j As Integer = 1 To count
                        nl.Add(itm)
                    Next
                Else
                    Dim idx As Integer = dict.IndexOf(itm)
                    If idx = -1 Then
                        dict.Add(itm)
                        idx = dict.Count - 1
                    End If
                    nl.Add(GetInt(count, idx))
                End If
                l_itm = itm
                count = 1
            End If
        Next
        l = nl
    End Sub
#End Region
 
End Class