epeg is a super-fast library for resizing JPEGs. It offers an improvement of at least an order of magnitude over other known libraries like ImageMagick. Here are some numbers indicative of its speed:

 $ time ./tclepeg test.jpeg test.jpg
 real    0m0.063s
 user    0m0.060s
 sys     0m0.000s

 $ time convert -resize 426x640 test.jpeg test.jpg 
 real    0m1.158s
 user    0m1.048s
 sys     0m0.052s

In the above example the improvement is 18 fold. test.jpeg is a 2592x3888 image that is resized to a 426x640 one using the epeg library. Convert is ImageMagick's convert utility. It took epeg 63 msec to do the conversion against 1158 msec for ImageMagick. These timings include reading/writing to disk. tclepeg takes about 1 msec to do the conversion in memory, on the same system.

tclepeg brings epeg's functionality to TCL by means of a binary Linux library that can be loaded into a TCL program. A package for Linux and the 32bit i386 architecture is provided together with the source code at

Usage (v0.4):

 epeg ?options ...? jpegdata
   -width image_width
   -height image_height
   -quality image_quality (1-100, default 50)
   -max max_dimension (default 64)

Usage example:

 load ./
 # read in a JPEG image
 set fd [open test.jpeg]
 fconfigure $fd -translation binary
 set img [read $fd]
 close $fd

 # write reduced image
 set fd [open out.jpeg w] 
 fconfigure $fd -translation binary 
 # let tclepeg do the work
 puts -nonewline $fd [epeg -width 320 -height 240 -quality 50 $img]
 close $fd

provided the library is in the present working directory directory.

MHo: Does it compile on windows?

dzach: If the dependency on libjpeg could be satisfied in windows, I think it could compile, but I haven't tried that.