.NET (Core and Framework)

// load a bitmap eventually converting to B/W<br />
private BitmapSource LoadBitmap(string sFile, bool bConvertToBW)<br />
{<br />
  BitmapImage bmp = new BitmapImage(new Uri(sFile));<br />
  if (bConvertToBW)<br />
    return new FormatConvertedBitmap(bmp, PixelFormats.BlackWhite, BitmapPalettes.BlackAndWhite, 0);<br />
  return bmp;<br />
}<br />
<br />
// Handler for Load... button:<br />
private void OnLoad(object sender, RoutedEventArgs e)<br />
{<br />
  OpenFileDialog dlg = new OpenFileDialog();<br />
  dlg.Filter = "Bitmap Files (*.bmp)|*.bmp";<br />
  if (dlg.ShowDialog() != true) return;<br />
<br />
  // load (and convert to BW if required)<br />
  // IF I PASS true I GET THE ISSUE DESCRIBED ABOVE. WITH false THE DUMP SEEMS TO WORK<br />
  BitmapSource bs = LoadBitmap(dlg.FileName, true);<br />
<br />
  int nBytesPerPixel = (bs.Format.BitsPerPixel + 7) / 8;<br />
  int nStride = bs.PixelWidth * nBytesPerPixel;<br />
  byte[] aPixels = new byte[bs.PixelHeight * nStride];<br />
  bs.CopyPixels(aPixels, nStride, 0);<br />
<br />
  // quick and dirty dump pixels to text (BACKGROUND is just a constant I manually set to 0, 255 etc<br />
  // according to the image I'm testing with, and represents the background color)<br />
  StringBuilder sb = new StringBuilder();<br />
  int nRow;<br />
  for (int y = 0; y < bs.PixelHeight; y++)<br />
  {<br />
    if (y > 0) sb.AppendLine("");<br />
    nRow = y * nStride;<br />
    for (int x = 0; x < bs.PixelWidth; x++)<br />
      sb.Append(aPixels[nRow + x * nBytesPerPixel] == BACKGROUND ? '.' : '#');<br />
   }<br />
  _txtOut.Text = sb.ToString();<br />
}