I would like to share a small tip on using images.

I had a method like this:

    ' Crop an image
    Public Function Crop() As Boolean
        Dim loGraphics As System.Drawing.Graphics = Nothing
        Dim loImage As System.Drawing.Bitmap = Nothing

        ' This is a placeholder
        loImage = New System.Drawing.Bitmap(nCropWidth, nCropHeight)

	loGraphics = System.Drawing.Graphics.FromImage(loImage)

        ' This will use oImage and obtain the new result into loImage
        loGraphics.DrawImage(oImage, New System.Drawing.Rectangle(0, 0, nCropWidth, nCropHeight), _
         nStartXPoint, nStartYPoint, nCropWidth, nCropHeight, System.Drawing.GraphicsUnit.Pixel)

	' Release this object
	loGraphics.Dispose()

        ' Take the new result and dump it back to oImage
        oImage = loImage.Clone

	' Release this object
	loImage.Dispose()

	Return True
End Function

On a very particular situation, I ended up with a file lock issue. I have been troubleshooting this for a while and only found the reason today.

When you look at the oImage assignation at the end, many would see it as ok. And, we could think like that even if we already had a reference of a file in oImage, a System.Drawing.Bitmap object.

But, in an isolated situation, it turned out this small dispose before assigning the new reference was needed:

    ' Crop an image
    Public Function Crop() As Boolean
        Dim loGraphics As System.Drawing.Graphics = Nothing
        Dim loImage As System.Drawing.Bitmap = Nothing

        ' This is a placeholder
        loImage = New System.Drawing.Bitmap(nCropWidth, nCropHeight)

	loGraphics = System.Drawing.Graphics.FromImage(loImage)

        ' This will use oImage and obtain the new result into loImage
        loGraphics.DrawImage(oImage, New System.Drawing.Rectangle(0, 0, nCropWidth, nCropHeight), _
         nStartXPoint, nStartYPoint, nCropWidth, nCropHeight, System.Drawing.GraphicsUnit.Pixel)

	' Release this object
	loGraphics.Dispose()

	' Clear the old reference otherwise, if we upload an image with a secondary directory and the secondary file
	' does not require a resize, we will have a lock issue
	oImage.Dispose()

        ' Take the new result and dump it back to oImage
        oImage = loImage.Clone

	' Release this object
	loImage.Dispose()

	Return True
End Function

So, with a System.Drawing.Bitmap object, even if we overwrite the object reference, the old reference remains stuck to it.