I released new versions of Salza2 and ZPNG today.
The Salza2 updates are minor tweaks the defsystem to fix build problems on a few Lisps. Thanks to Chaitanya Gupta for bringing it to my attention. Get the new Salza2 here.
ZPNG changes are more extensive. I added COPY-PNG and PNG= functions from Tobias C. Rittweiler (thanks, tcr!). I also added a new class and protocol for writing out PNG files incrementally, row-by-row, so you don't have to create or convert all your image data to a big ZPNG array to write it out to a file. Doing it row-by-row will save memory. In theory you could create a PNG with overall image data much too big to fit in memory, as long as you can fit a single row. Get the new ZPNG here.
If you're into git, you can check out both projects from git.xach.com.