Untitled

RenderTargetBitmap DPI for drawing application
// Get system DPI
Matrix m = PresentationSource.FromVisual(Application.Current.MainWindow).CompositionTarget.TransformToDevice;
if (m.M11 > 0 && m.M22 > 0)
{
    dpiXFactor = m.M11;
    dpiYFactor = m.M22;
}
else
{
    // Sometimes this can return a matrix with 0s. Fall back to assuming normal DPI in this case.
    dpiXFactor = 1;
    dpiYFactor = 1;
}