On Tue, 15 Jul 2014, Peter Münster wrote:

> There is also an old module t-degrade.tex but I don't know, if it still
> works with recent ConTeXt versions.

It is possible to create a wrapper around t-filter to provide the 
functionality of t-degrade and/or grph-downsample, so that one could use:

    \downsample[filename][options]

The main advantage is that one can use all the options of t-filter module: 
specify the cache directory, force reruns, etc. Let me know if there is 
any interest in such a wrapper.

Aditya