GhostScript: A Versatile PDF and PostScript Tool (with examples)

GhostScript is a powerful interpreter for Portable Document Format (PDF) and PostScript (PS) files. It allows users to manipulate and convert files, view documents, and perform various tasks related to PDFs and PS files. GhostScript’s flexibility makes it a valuable tool for developers, graphic designers, and anyone handling PDF or PostScript files.

Use case 1: Viewing a PDF File

Code:

gs -dQUIET -dBATCH file.pdf

Motivation:

Viewing a PDF file directly from the command line without opening a specialized application can be particularly useful when working on a system with limited resources or in a remote environment. GhostScript provides a straightforward way to accomplish this, ensuring quick access to document content.

Explanation:

• gs: This is the command to invoke GhostScript.
• -dQUIET: Suppresses the regular startup output, which reduces the noise in your terminal.
• -dBATCH: Ensures that GhostScript exits after processing the final file, preventing it from transitioning into an interactive mode.
• file.pdf: Indicates the file you wish to view.

Example output:

When executed, the command will open the specified PDF file using GhostScript’s viewer mode, allowing you to navigate through the pages of the document.

Use case 2: Reducing PDF File Size for E-book Devices

Code:

gs -dNOPAUSE -dQUIET -dBATCH -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -sOutputFile=output.pdf input.pdf

Motivation:

E-book readers often have limited storage space, so reducing the file size of PDFs is crucial. This use case allows you to compress a PDF by lowering the image quality to 150 dpi, making it more manageable for e-book devices.

Explanation:

• -dNOPAUSE: Prevents GhostScript from pausing for user interaction after each page is processed.
• -dQUIET: Suppresses startup messages and other informational output.
• -dBATCH: Ensures the program exits after completing the task.
• -sDEVICE=pdfwrite: Specifies the output format, which is PDF in this case.
• -dPDFSETTINGS=/ebook: Adjusts the settings for optimal eBook viewing, reducing image resolution.
• -sOutputFile=output.pdf: Sets the name of the output file.
• input.pdf: The original PDF file to be processed.

Example output:

After execution, a smaller PDF file named “output.pdf” is created, suitable for storage on an e-book device.

Use case 3: Converting PDF Pages to Images

Code:

gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=jpeg -r150 -dFirstPage=1 -dLastPage=3 -sOutputFile=output_%d.jpg input.pdf

Motivation:

Sometimes, it is necessary to convert specific pages of a PDF into image formats for presentations, reports, or online sharing. This command extracts pages and saves them as JPEG images, with 150 dpi resolution for decent quality and moderate file size.

Explanation:

• -sDEVICE=jpeg: Specifies that the output format should be JPEG.
• -r150: Sets the resolution to 150 dots per inch.
• -dFirstPage=1: Marks the first page to be converted.
• -dLastPage=3: Indicates the last page to be converted.
• -sOutputFile=output_%d.jpg: Sets the naming pattern for output files, where %d will be replaced by the page number.
• input.pdf: Specifies the input PDF.

Example output:

The output will be JPEG files named “output_1.jpg”, “output_2.jpg”, and “output_3.jpg”, each corresponding to a page from the PDF.

Use case 4: Extracting Pages from a PDF File

Code:

gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=output.pdf input.pdf

Motivation:

Extracting specific pages from a PDF can be necessary for creating excerpts or isolating critical information. This simplifies the document-sharing process, allowing for more targeted communication.

Explanation:

• -sDEVICE=pdfwrite: Defines PDF as the output format.
• -sOutputFile=output.pdf: Specifies the output file name.
• input.pdf: The source PDF file from which pages are extracted.

Example output:

The command will generate a new PDF file, “output.pdf”, containing the specified pages from the original document.

Use case 5: Merging PDF Files

Code:

gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=output.pdf input1.pdf input2.pdf

Motivation:

Combining various PDF files into one cohesive document can be instrumental when assembling reports or consolidating related documents for easier distribution and review.

Explanation:

• -sDEVICE=pdfwrite: Ensures the merged output is in PDF format.
• -sOutputFile=output.pdf: Specifies the final, combined PDF filename.
• input1.pdf input2.pdf: The list of PDF files to merge.

Example output:

A single merged PDF file, “output.pdf”, which contains all input files in sequence, provides an orderly compilation of content.

Use case 6: Converting a PostScript File to PDF

Code:

gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=output.pdf input.ps

Motivation:

Converting PostScript files to PDF format broadens their accessibility and compatibility, as PDF is a more widely supported and used format, especially for document sharing and printing.

Explanation:

• -sDEVICE=pdfwrite: Specifies that the output should be in PDF format.
• -sOutputFile=output.pdf: Defines the name of the converted PDF file.
• input.ps: The original PostScript file that needs conversion.

Example output:

Execution results in a PDF file “output.pdf,” converted from the original PostScript, suitable for distribution and viewing across different platforms.

Conclusion:

GhostScript is a versatile tool for managing PDF and PostScript files, offering a variety of functionalities to suit different needs. From viewing and reducing file sizes to converting and merging documents, GhostScript provides powerful solutions, especially in environments where comprehensive software might not be available. With these examples, users can effectively harness GhostScript’s capabilities to handle their document processing tasks with ease.