Here's some code you can put in a module, that will let you convert any StdPicture object into an ordinary byte array that contains the pixel data in 32bit-per-pixel format. In addition to it being 32bit, it makes sure that the value for field Height in the BitmapInfoHeader structure used in the conversion is a negative number, so that the first row of pixels (y=0) is always at the top (like with most image formats) rather than at the bottom (like it usually is for BMP files). The below code is fully commented, so you can see how it works.
After calling this to get the pixels in an array, to get the width you just need to do UBound(arrayname,2)+1 to get the width in the calling function, and UBound(arrayname,3)+1 to get the height. UBound(arrayname,1)+1 always is 4, because there are 4 bytes per pixel, and the first dimension in the array is the color channel selector (0=B, 1=G, 2=R, 3=unused). Here's some sample code for sample code for how to use it to load a picture file directly into a byte array, and then displaying it to the form (albeit using the inefficient PSet statement).
Note that LoadPicture only works with BMP, JPG, and GIF formats. If you want to support TIF and PNG, you will need to use WIA 2.0, which comes with all versions of Windows since Vista, but not XP (though it might be available in Windows XP with SP3).
Code:
Private Declare Function GetDIBits Lib "gdi32.dll" (ByVal hDC As Long, ByVal hBitmap As Long, ByVal nStartScan As Long, ByVal nNumScans As Long, ByRef lpBits As Any, ByRef lpBI As BITMAPINFO, ByVal wUsage As Long) As Long
Private Declare Function CreateCompatibleDC Lib "gdi32.dll" (ByVal hDC As Long) As Long
Private Declare Function DeleteDC Lib "gdi32.dll" (ByVal hDC As Long) As Long
Private Type BITMAPINFOHEADER
biSize As Long
biWidth As Long
biHeight As Long
biPlanes As Integer
biBitCount As Integer
biCompression As Long
biSizeImage As Long
biXPelsPerMeter As Long
biYPelsPerMeter As Long
biClrUsed As Long
biClrImportant As Long
End Type
Private Type RGBQUAD
rgbBlue As Byte
rgbGreen As Byte
rgbRed As Byte
rgbReserved As Byte
End Type
Private Type BITMAPINFO
bmiHeader As BITMAPINFOHEADER
bmiColors As RGBQUAD
End Type
Public Function StdPictureToPix(ByRef Picture As StdPicture) As Byte()
Dim Pix() As Byte
Dim BMI As BITMAPINFO
Dim Width As Long
Dim Height As Long
Dim hDC As Long
hDC = CreateCompatibleDC(0) 'Create a temporary in-memory device context
BMI.bmiHeader.biSize = Len(BMI.bmiHeader) 'Initialize BitmapInfoHeader with header size
GetDIBits hDC, Picture.Handle, 0, 0, ByVal 0&, BMI, 0 'Get Information about the image
'Set up BitmapInfoHeader for getting the pixel data in 32bit format, and with y=0 on the top
With BMI.bmiHeader
.biBitCount = 32
.biClrUsed = 0
.biClrImportant = 0
.biSizeImage = 0
.biCompression = 0
Width = .biWidth
Height = Abs(.biHeight)
.biHeight = -Height
End With
'32bit format has, for each pixel, 3 color channels in the order B, G, R, and an unused channel
'This always satisfies the condition that each image row must have a multiple-of-4 byte count
ReDim Pix(3, Width - 1, Height - 1) 'Initialize array for holding pixel data
GetDIBits hDC, Picture.Handle, 0, Height, Pix(0, 0, 0), BMI, 0 'Get pixel data
DeleteDC hDC 'Get rid of temporary in-memory device context
StdPictureToPix = Pix()
End FunctionCode:
Private Sub Form_Load()
Dim x As Long
Dim y As Long
Dim Pix() As Byte
Dim Img As New ImageFile
Pix() = StdPictureToPix(LoadPicture("picturefile.jpg"))
Show
For y = 0 To UBound(Pix, 3)
For x = 0 To UBound(Pix, 2)
PSet (x, y), RGB(Pix(2, x, y), Pix(1, x, y), Pix(0, x, y))
Next x
DoEvents
Next y
End Sub