如何使用Ghostscript将PDF转换为图像

Question

I found that Ghostscript is able to convert PDF to Image format.

I tried PDF to Image Converter but not able to understand it clearly.

I have installed gs905w64.exe but when I tried to add reference to my web application I am getting this error.

A reference to gsdll32.dll could not be added. No type libraries were found in the component.

Answer 1

You can use C# to run the GhostScript command line or use Platform Invoke (pInvoke) calls to call the GhostScript dll directly.

GhostScript is primarily file based, so the input is path to a file on disk and the output is the creation of files on disk. The parameters used to call either the dll or exe are basically the same, so there is not a huge benefit to calling the dll directly, but does make for nicer code.

I have C# wrapper that can be used to call the ghostscript dll, if you email me (address on profile) I will sent it to you.

HTH

UPDATE:

code repo moved to https://bitbucket.org/brightertools/ghostscript

Answer 2

You Do not need to add any DLL reference to your project. First download the gs910w32.exe application file then install it to your local computer. Get the location of the installed .exe file eg:-

"C:\\Program Files (x86)\\gs\\gs8.64\\bin\\gswin32.exe"

use it in your C# application as :

  private void PdfToJpg(string inputPDFFile, string outputImagesPath)
        {
            string ghostScriptPath = @"C:\Program Files (x86)\gs\gs8.64\bin\gswin32.exe";
            String ars = "-dNOPAUSE -sDEVICE=jpeg -r102.4 -o" + outputImagesPath + "%d.jpg -sPAPERSIZE=a4 " + inputPDFFile;
            Process proc = new Process();
            proc.StartInfo.FileName = ghostScriptPath;
            proc.StartInfo.Arguments = ars;
            proc.StartInfo.CreateNoWindow = true;
            proc.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
            proc.Start();
            proc.WaitForExit();
        }

IF your input PDF file name has any spaces, you need to change the argument to

String ars = "-dNOPAUSE -sDEVICE=jpeg -r102.4 -o" + outputImagesPath + "%d.jpg -sPAPERSIZE=a4 " +"\"" + inputPDFFile + "\"";

you can specify the output image's aspect ratio in the argument with the -r flag. If you use "-r300" the width of the image will be 3000 pixel and height will change accordingly, from the above argument you will get 1024 to 768 size jpg image.

Answer 3

The gsdll32.dll file is not a managed .NET library. You can't reference it in your project. You have to include it in your project as "content" (menu: Add existing item) and let VS copy it to the output directory. Meanwhile you should read the Ghostscript API docs and this article on PInvoke.net on how to reference the Ghostscript functions.

Keep in mind that Ghostscript is all unmanaged code and that you have to do the clean-up yourself after using the library.

Edit: What Robert said is important, too. Of course, you have to use the correct version of the Ghostscript library.

Answer 4

Why do you try to add the library as reference to your project? gsdll32.dll is a native dll, not a Dot-Net library.

When I build the sample project using Visual C# Express 2010 I get an exe file. If I execute it it tries to access the gsdll32.dll . The problem is now that on a 64bit system a 64bit executable is generated but the gsdll32.dll is compiled for 32bit.

The correct solution would be to modify the source code and replace gsdll32.dll with gsdll64.dll everywhere it occurs. The simpler solution is to use the 64 bit version of Ghostscript, copy the gsdll64.dll into the same directory as the ConvertPDF.exe and rename it to gsdll32.dll . This definitely works - just tested and converted a PDF to TIFF.

Answer 5

you need to run the below command to reference the library http://www.nuget.org/packages/GhostScriptSharp/

VS2012 --> Tools --> Library Package Manager --> Package Manager Console