fastest byte array of a bitmap ?

[sequoyan]

Hello,

I've written a small program that gets a bitmap into an array, does some if-then routienes on the raster data, then puts the array back to the bitmap file.

But it is very slow.

Would it be faster if I used a picture box and DIB functions (a DC etc.)?

Thanks for any help

- Jake

[Electroman]

This should help you if you do decide to use a picture box or if you decide to use a DC instead of the picture box see this thread http://www.vbforums.com/showthread.p...hreadid=210500 which sequoyan will already know of. This example inverts each pixel.

Private Declare Function VarPtrArray Lib "msvbvm50.dll" Alias "VarPtr" (Ptr() As Any) As Long
Private Declare Function VarPtr Lib "msvbvm50.dll" (Ptr As Any) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
Private Declare Function GetObjectAPI Lib "gdi32" Alias "GetObjectA" (ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As Long
 
Private Type SAFEARRAYBOUND
    cElements As Long
    lLbound As Long
End Type
 
Private Type SAFEARRAY2D
    cDims As Integer
    fFeatures As Integer
    cbElements As Long
    cLocks As Long
    pvData As Long
    Bounds(0 To 1) As SAFEARRAYBOUND
End Type
 
Private Type BITMAP
    bmType As Long
    bmWidth As Long
    bmHeight As Long
    bmWidthBytes As Long
    bmPlanes As Integer
    bmBitsPixel As Integer
    bmBits As Long
End Type
 
 
'Code
Dim i As Integer
Dim j As Integer
Dim pic() As Byte
Dim sa As SAFEARRAY2D
Dim bmp As BITMAP
Dim r As Long, g As Long, b As Long
 
GetObjectAPI Picture1.Picture, Len(bmp), bmp
 
With sa
    .cbElements = 1
    .cDims = 2
    .Bounds(0).lLbound = 0
    .Bounds(0).cElements = bmp.bmHeight
    .Bounds(1).lLbound = 0
    .Bounds(1).cElements = bmp.bmWidthBytes
    .pvData = bmp.bmBits
End With
 
CopyMemory ByVal VarPtrArray(pic), VarPtr(sa), 4
 
For i = 0 To UBound(pic, 1) - 3 Step 3
    For j = 0 To UBound(pic, 2)
        r = pic(i + 2, j)
        g = pic(i + 1, j)
        b = pic(i, j)
        pic(i, j) = 255 - b
        pic(i + 1, j) = 255 - g
        pic(i + 2, j) = 255 - r
    Next
Next
 
CopyMemory ByVal VarPtrArray(pic), 0&, 4

[sequoyan]

Thanks for the code Electroman.

What do you think is the fastest? The simple "Get" byte array that I'm currently using, a DC, or a picture box?

Thanks for any advice

- Sequoyan

[Electroman]

Personaly I would choose the DC because its the fastest way to edit an image Pixel by pixel but I aint sure about the speed of the "Get" byte array.

I should point out the code I gave is for 24bit Bitmaps only and it would need some slight changes for other bpp's. and I think were the -3 is I think it should be -1 but i'm busy trying to fix that anyway.

[sequoyan]

can anyone second Electroman's opintion that a DC would be faster?

Thanks

- Jake

[Electroman]

Check out this example that I made, http://www.Electroman.co.uk/VBExampl...xelEditing.zip, it compares using GetPixel and SetPixelV to my method.

[sequoyan]

That's really cool. Thanks for the sample.

Just for the hell of it I'm posting the section of code that is giving me a headache. It's part of a larger sub but I know that it is this part that is running really slow. Any help in optomizing it would be greatly appreciated.

The procedure is at the beginning of the code.

Thanks

- Jake

Here's the code that I would like to run faster:

' it comes in already having the bitmap file open for binary as #f
...
 
MsgBox ("Begin Color Table Fix")
 
    ' PROCEDURE:
    ' 1) Get the BGR value of the background color
    ' 2) Get the BGR value of the color currently in table position 0
    ' 3) Put the BGR value of the background color into table position 0
    ' 4) Put the BGR value of the old position 0 color into the position that the background color came from
    ' 5) Change the raster data for the bg pixels from old color table position of bg color to "00"
    '    and change the raster data for the pixels that referenced the old position 0 color to that color's new color table position
    
MsgBox ("1")
Dim OrigBGColor
'MsgBox (BOB_p1)
Get #f, BOB_p1, BOB_FstByteColTblRef
'MsgBox ("First Pixel Color Table Reference: " & BOB_FstByteColTblRef)
 
If BOB_FstByteColTblRef > 0 Then
 
    ' 1) Get the BGR value of the background color
    Dim decColTblRef_1
    Dim decColTblRef_2
    Dim decColTblRef_3
    Dim decColTblRef_4
    Dim decColTblRef_5
    Dim decColTblRef_6
 
    Dim bgColBlVal As Byte
    Dim bgColGrVal As Byte
    Dim bgColRdVal As Byte
    
    decColTblRef_1 = (BOB_FstByteColTblRef * 4)
    decColTblRef_2 = (decColTblRef_1 + 55)
    
    decColTblRef_4 = (decColTblRef_2)       ' position in byte array of blue val of bg color
    decColTblRef_5 = (decColTblRef_2 + 1)   ' position in byte array of green val of bg color
    decColTblRef_6 = (decColTblRef_2 + 2)   ' position in byte array of red val of bg color
 
    Get #f, decColTblRef_4, bgColBlVal
    Get #f, decColTblRef_5, bgColGrVal
    Get #f, decColTblRef_6, bgColRdVal
MsgBox ("2")
    'MsgBox ("the background color of the bitmap is: " & vbNewLine & "Blue = " & bgColBlVal & " Green = " & bgColGrVal & " Red = " & bgColRdVal)
 
    'MsgBox ("BL: " & bgColBlVal & " GR: " & bgColGrVal & " RD: " & bgColRdVal)
    
    ' 2) Get the BGR value of the color currently in table position 0
    Dim OrigPos0Bl As Byte
    Dim OrigPos0Gr As Byte
    Dim OrigPos0Rd As Byte
    
    Get #f, 55, OrigPos0Bl
    Get #f, 56, OrigPos0Gr
    Get #f, 57, OrigPos0Rd
    
    'MsgBox ("Bl: " & OrigPos0Bl & " Gr: " & OrigPos0Gr & " Rd: " & OrigPos0Rd)
    
    ' 3) Put the BGR value of the background color into table position 0
    Put #f, 55, bgColBlVal
    Put #f, 56, bgColGrVal
    Put #f, 57, bgColRdVal
        
    ' 4) Put the BGR value of the old position 0 color into the position that the background color came from
    ' put it in whatever position the bgcol came (BOB_FstByteColTblRef) from
    
    Put #f, decColTblRef_4, OrigPos0Bl
    Put #f, decColTblRef_5, OrigPos0Gr
    Put #f, decColTblRef_6, OrigPos0Rd
MsgBox ("3")
    ' 5) Change the raster data for the bg pixels from old color table position of bg color to "00"
    ' the parse is: if byte = BOB_FstByteColTblRef Then put byte = "ff"
    ' and...Change the raster data for the pixels that referenced the old position 0 color to that color's new color table position
            
        Dim tfParInt
        Dim tfParInt_1
        Dim rByteValHex_1 As Byte
        Dim rByteValHex2 As Byte
        Dim tfBGColRefTemp As Byte
        tfBGColRefTemp = 255
        Dim tfOthColRefTemp As Byte
        tfOthColRefTemp = 254
        'MsgBox (BOB_FstByteColTblRef)
        'MsgBox (BOB_p1)
        For tfParInt = BOB_p1 To lngFileLen
            rByteValHex_1 = argArray_raster(tfParInt)
            'MsgBox (rByteValHex_1)
            If rByteValHex_1 = BOB_FstByteColTblRef Then
                'MsgBox ("here 1")
                Put #f, tfParInt, tfBGColRefTemp
            End If
        
            If rByteValHex_1 = 0 Then
                'MsgBox ("here 2")
                Put #f, tfParInt, tfOthColRefTemp
            End If
        Next tfParInt
MsgBox ("4")
        On Error Resume Next
        
        For tfParInt_1 = 1 To lngFileLen
            Dim tfParser
            tfParser = (BOB + tfParInt_1)
            'MsgBox ("tfParser = (should be 347)" & tfParser)
            Get #f, tfParser, rByteValHex2
           
            'MsgBox ("here  3, rByteValHex2 = (should be 255)" & rByteValHex2)
            If rByteValHex2 = 255 Then
           '     MsgBox ("reached here 4")
                Put #f, tfParser, 0
            Else
                If rByteValHex2 = 254 Then
           '         MsgBox ("reached here 5")
                    Put #f, tfParser, BOB_FstByteColTblRef
                End If
            End If
        Next tfParInt_1
MsgBox ("5")
Else
    MsgBox ("The background color is already in the first color table position")
End If
 
 
MsgBox ("End Color Table Fix")
 
...

[Electroman]

I'll have a look and I see what I can do.

[Electroman]

My first thoughts would be to change the variables to arrays because arrays can be accessed alot faster. Also you've declared alot of variables without a type, I belive they're meant to be bytes so declaring them as types would take up 16 times less memory(Varient is 128Bit I belive and Byte is 8bit).
Sorry but thats all I can think of coz the rest of your code is just the accessing of the file I don't know of another way of to do that quicker. My only idea on that is: is there a way to load the whole file in one go into a byte array then you could very simply edit the byte array and wouldn't need most of the variables your currently using, not to mention i'm sure its a lot faster to access files all in one go rather than reading little bits and writing little bits.

Check out this Article which explains how to make sure your programs are as efficient as possible:
http://216.26.168.92/vbsquare/misc/efficient/index.html

Hope this helps.