ImageMagick Pdf到图像的转换太慢

Question

I'm using ImageMagick.NET for generating image from pdf. Its working, but the conversion process is too slow. Code -->

 public void ProcessRequest(HttpContext context)
    {
        if (context.Request["id"] != null)
        {
            string id = context.Request["id"].ToString();


            MagickReadSettings settings = new MagickReadSettings();
            settings.Density = new MagickGeometry(300, 300);

            using (MagickImageCollection images = new MagickImageCollection())
            {
                images.Read(System.Web.HttpContext.Current.Server.MapPath(string.Format("~/Reciepts/order{0}.pdf", id)), settings);

                MagickImage vertical= images.AppendVertically();
                 using (var memoryStream = new MemoryStream())
                {
                    vertical.ToBitmap().Save(memoryStream, ImageFormat.Jpeg);
                    var d = memoryStream.GetBuffer();
                    context.Response.Clear();
                    context.Response.ContentType = "image/jpeg";
                    context.Response.BinaryWrite(d);
                    context.Response.End();
                }
            }

        }
    }

Where i can improve ?

Answer 1

You are using Magick.NET not ImageMagick.NET.

It is not necessary to create a bitmap before you send it to the output stream. You can just do this:

using (MagickImage vertical=images.AppendVertically())
{
  vertical.Format = MagickFormat.Jpeg;
  vertical.Write(context.Response.OutputStream);
}

And maybe you should cache the result to a file?

Answer 2

If you decided to use Magick.NET, method is not wrong. First answer gives you "Using" statement for MagickImage . But this differs only a few milliseconds to finish the job.

I see that the slow line is this line:

images.Read(System.Web.HttpContext.Current.
    Server.MapPath(string.Format("~/Reciepts/order{0}.pdf", id)), settings);

because of settings objects properties. Your property says that image must be in 300dpi and 300 might be very high for your cpu:

settings.Density = new MagickGeometry(300, 300);

You can try to use lower density, not 300dpi. Lower density is more fast:

settings.Density = new Density(72, 72);

I think there must be another fast way to create image from pdf file. Magick.NET uses Ghostscript to generate image from pdf and Ghostscript is slow and sometimes not successful to generate image from complicated (layered) pdf's.