Getting an exception using a background worker

Try to edit the ProgressChanged handler and also process the RunWorkerCompleted event:

Private Sub BGWProcess_ProgressChanged(sender As Object, e As ProgressChangedEventArgs) Handles BGWProcess.ProgressChanged
    TxtProgress.Text = e.ProgressPercentage.ToString
    'PictureBox1.Image = Destination ' <-- REMOVED
End Sub

Private Sub BGWProcess_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs) Handles BGWProcess.RunWorkerCompleted
    PictureBox1.Image = Destination
End Sub

In addition, before starting the worker, make sure that Destination is not assigned to picture box. For example:

PictureBox1.Image = Nothing
BGWProcess.RunWorkerAsync()

Hi @Devon Nullman ,

Even though you're not explicitly using the bitmap elsewhere, the BackgroundWorker operates on a different thread than the UI, which could cause conflicts when accessing the same bitmap.

Try locking the Destination bitmap to ensure exclusive access during the pixel manipulation using the Bitmap.LockBits Method.

Private Sub BGWProcess_DoWork(sender As Object, e As DoWorkEventArgs) Handles BGWProcess.DoWork
    Dim bmpDataSource As BitmapData = Source.LockBits(New Rectangle(0, 0, Source.Width, Source.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb)
    Dim bmpDataDestination As BitmapData = Destination.LockBits(New Rectangle(0, 0, Destination.Width, Destination.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)

    Try
        For Y = 0 To hgt
            For X = 0 To wid
                If BGWProcess.CancellationPending Then Exit Sub

                Dim srcColor As Color = Color.FromArgb(Marshal.ReadInt32(bmpDataSource.Scan0, (Y * bmpDataSource.Stride) + (X * 4)))
                
                Marshal.WriteInt32(bmpDataDestination.Scan0, (Y * bmpDataDestination.Stride) + (X * 4), srcColor.ToArgb())
            Next

            BGWProcess.ReportProgress(Y)
        Next
    Finally
        Source.UnlockBits(bmpDataSource)
        Destination.UnlockBits(bmpDataDestination)
    End Try
End Sub

Best Regards.

Jiachen Li

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