在Ubuntu 10.04，我已经安装了poppler的-utils软件包，以便能够运行pdftoppm。
我的目标是PDF文件转换为JPEG文件，但我没有可用的选项/标志。 我似乎有唯一的光栅化是PNG支持。
可能有人请告知我怎样才能得到支持JPEG？ 非常感谢。
（见我的选项列表下方运行后：pdftoppm --help）：
pdftoppm version 0.12.4
Copyright 2005-2009 The Poppler Developers - http://poppler.freedesktop.org
Copyright 1996-2004 Glyph & Cog, LLC
Usage: pdftoppm [options] [PDF-file [PPM-file-prefix]]
-f <int> : first page to print
-l <int> : last page to print
-r <fp> : resolution, in DPI (default is 150)
-rx <fp> : X resolution, in DPI (default is 150)
-ry <fp> : Y resolution, in DPI (default is 150)
-scale-to <int> : scales each page to fit within scale-to*scale-to pixel box
-scale-to-x <int> : scales each page horizontally to fit in scale-to-x pixels
-scale-to-y <int> : scales each page vertically to fit in scale-to-y pixels
-x <int> : x-coordinate of the crop area top left corner
-y <int> : y-coordinate of the crop area top left corner
-W <int> : width of crop area in pixels (default is 0)
-H <int> : height of crop area in pixels (default is 0)
-sz <int> : size of crop square in pixels (sets W and H)
-cropbox : use the crop box rather than media box
-mono : generate a monochrome PBM file
-gray : generate a grayscale PGM file
-png : generate a PNG file
-freetype <string> : enable FreeType font rasterizer: yes, no
-aa <string> : enable font anti-aliasing: yes, no
-aaVector <string> : enable vector anti-aliasing: yes, no
-opw <string> : owner password (for encrypted files)
-upw <string> : user password (for encrypted files)
-q : don't print any messages or errors
-v : print copyright and version info
-h : print usage information
-help : print usage information
--help : print usage information
-? : print usage information
