Setting auto-height/width for converted Jpeg from PDF using GhostScript

Question

I am using GS to do conversion from PDF to JPEG and following is the command that I use:

gs -sDEVICE=jpeg -dNOPAUSE -dBATCH -g500x300 -dPDFFitPage -sOutputFi         


        

Answer 1

You could write a PostScript program to do this readily enough. Here is a start:

%!
% usage: gs -sFile=____.pdf  scale.ps

/File where not {
  (\n   *** Missing source file. \(use -sFile=____.pdf\)\n) =
  Usage
} {
  pop
}ifelse

% Get the width and height of a PDF page
%
/GetSize {
  pdfgetpage currentpagedevice
  1 index get_any_box 
  exch pop dup 2 get exch 3 get
  /PDFHeight exch def
  /PDFWidth exch def
} def


%
% The main loop
% For every page in the original PDF file
%
1 1 PDFPageCount 
{
  /PDFPage exch def
  PDFPage GetSize

% In here, knowing the desired destination size
% calculate a scale factor for the PDF to fit
% either the width or height, or whatever
% The width and height are stored in PDFWidht and PDFHeight
  PDFPage pdfgetpage
  pdfshowpage
} for

pdfgetpage and pdfshowpage are internal Ghostscript extensions to the PostScript language for handling PDF files.