New Post: Scaling large images

Thank you for answer.
I'm using folowwing code:

MagickNET.SetCacheThreshold(int.MaxValue);
MagickNET.SetTempDirectory(@"D:\");
using (var img = new MagickImage(@"D:\sample.psd"))
{
    img.ColorType = ColorType.Grayscale;
    img.IsMonochrome = true;
    img.Scale(img.Width * 4, img.Height * 4);
    img.Write(@"D:\resultImage.psd");
}

For sample file application creates 2 temp files with size of 580 Mb and 9.2 Gb and it takes 824 seconds to proceed image. Application doesn't utilize memory but uses disk a lot.