http://www.ruijiang.com/ 

MultiConv is a command line tool which can resize/convert multiple image files 
(bmp, jpg, tif...) at the same time. Best for producing thumbnails or extracting 
multiple pages from a tif file. Very good reduction quality. 

Usage:
MultiConv, resizes/converts multiple image files. Usage:

  MultiConv /s:source /d:destpath /x:destext /m:mode /w:width /h:height
  /r:ratio /o /?


Basic Options:

      /s:sourceSource image file/directory name.
      /d:destpathDestination path.
      /x:destextDestination file type. Default: jpg.
      /m:modeResize mode. Default is "n"-No resize.
      /m:nNo resize.
      /m:aAbsolute width and height.
      /m:wChange width only.
      /m:hChange height only.
      /m:wrChange width, and keep ratio.
      /m:hrChange height, and keep ratio.
      /m:rResize according to ratio.
      /w:widthNew width. Required if mode is a, w or wr.
      /h:heightNew height. Required if mode is a, h or hr.
      /r:ratioResize ratio. Required is mode is r.
      /oOverwrite if destination file exists.
      /?Print this help.

Advanced Options:

/pre:prefix
	Add prefix to the output file name. e.g., if the source file 
      name is "image1.bmp", and you specify "/pre:s_" in the command line, the 
      output file name would be "s_image1.bmp" 
/suf:suffix
	Add suffix to the output file name.
/nr
	Do not recursively traverse the whole directory. Only look for files 
      directly in the specified source directory. 
/zp:zeropadding
      For multi-page image file like tif, if the source file name 
      is "pic.tif", then generated file names would be: "pic1.jpg", "pic2.jpg" 
      ... However, if you specify "/zp:2", then numbers will be padded 0's if 
      the width of the number is less than 2. Thus the output file name would 
      be: "pic01.jpg", "pic02.jpg", ... Default /zp value is 2. 

Examples: 
MultiConv /s:d:\photos /d:c:\temp\photo /m:hr /h:150
  Convert all image files in d:\photos to jpg files with height of 150 pixels. 
Converted files will be stored in c:\temp\photo.
MultiConv /s:d:\photos\photo1.tif /d:c:\temp\photo /x:bmp /m:r /r:0.5
  Convert file d:\photos\photo1.tif to bmp files. Compress image size to 50%. 
Converted files will be stored in c:\temp\photo.

Supported file format
      File typeFile ExtensionComment
      BMP*.bmpRead/Write
      ICO*.icoRead Only
      JPEG*.jpg, *.jpegRead/Write
      PCX*.pcxRead Only
      PNG*.pngRead/Write
      TARGA*.tgaRead Only
      TIFF*.tif, *.tiffRead/Write, Support multiple pages