Problem Statement

Using the data storage type defined on this page for raster images, delegate writing a JPEG file through a pipe using the output_ppm function defined on this other page. There are various utilities that can be used for this task, for example: cjpeg (package "jpeg-progs" on Linux, or "media-libs/libjpeg-turbo" on Gentoo), ppmtojpeg (package "netpbm" on Linux), convert (from ImageMagick, multi-platform).

Let's start with the solution:

img:=PPM.readPPMFile("fractal.ppm");
p:=System.popen(0'|convert ppm:- jpg:"fractal.jpg"|,"w");
img.write(p); p.close();