Display BMP on console V2 VB.Net Exercise - Visual Basic Programming Course

Imports System
Imports System.IO
Public Class DisplayPGM
    Public Shared Sub Main(ByVal args As String())
        Dim inputFile As BinaryReader
        Dim fileName As String = ""

        If args.Length <> 1 Then
            Console.WriteLine("Please enter filename...")
            fileName = Console.ReadLine()
        Else
            fileName = args(0)
        End If

        If Not File.Exists(fileName) Then
            Console.WriteLine("the file not exists")
            Return
        End If

        Try
            inputFile = New BinaryReader(File.Open(fileName, FileMode.Open))
            Dim tag1 As Char = Convert.ToChar(inputFile.ReadByte())
            Dim tag2 As Char = Convert.ToChar(inputFile.ReadByte())
            Dim endOfLine As Byte = inputFile.ReadByte()

            If (tag1 <> "P"c) OrElse (tag2 <> "5"c) OrElse (endOfLine <> 10) Then
                Console.WriteLine("The file is not a PGM")
                inputFile.Close()
                Return
            End If

            Dim data As Byte = 0
            Dim sizeOfImage As String = ""

            While data <> 10
                data = inputFile.ReadByte()
                sizeOfImage += Convert.ToChar(data)
            End While

            Dim widthAndHeight As String() = sizeOfImage.Split(" "c)
            Dim width As Integer = Convert.ToInt32(widthAndHeight(0))
            Dim height As Integer = Convert.ToInt32(widthAndHeight(1))
            Dim maxIntensity1 As Char = Convert.ToChar(inputFile.ReadByte())
            Dim maxIntensity2 As Char = Convert.ToChar(inputFile.ReadByte())
            Dim maxIntensity3 As Char = Convert.ToChar(inputFile.ReadByte())
            Dim endOfLine1 As Byte = inputFile.ReadByte()

            If (maxIntensity1 <> "2"c) OrElse (maxIntensity2 <> "5"c) OrElse (maxIntensity3 <> "5"c) OrElse (endOfLine1 <> 10) Then
                Console.WriteLine("Must be 256 grey levels")
                inputFile.Close()
                Return
            End If

        Catch e As Exception
            Console.WriteLine("Error: {0}", e)
        End Try
    End Sub
End Class