4 of the pdf's tests_private/comparefiles have extremely large dimensions (3000pt = 3.5 foot): Bug688778.pdf 1950.54 x 2385.74 pdf 1.4 Bug689581.pdf 3003.99 x 5382 pdf 1.4 Bug690379.pdf 4535.43 x 8503.94 pdf 1.6 Bug689982.pdf - 1887.87 x 2681.57 pdf 1.5 pxl internally uses a lot of 16-bit integers; at -r600 signed integers overflow at about 4000 pt's. Bug689982.pdf seems to be missing some features, Bug690379.pdf is known to be empty, and Bug689982.pdf was apparently derived from Bug689918.pdf. Superficially only Bug689982.pdf shows clear rendering problems. (features missing). This bug is to track co-ordinate addressing and rendering issues with large dimensions, (i.e. pxlcolor should do the rendering correctly, resource permitting). resource usage is tracked through the accompanying bug 690945.
The pdfwrite device uses (I think it still does) to reduce the resolution if the PageSize exceeds the cooordinate space. Perhaps this could be done with the pxl*** devices since PageSize is set before anything is written to the page. AFAIK, 300 dpi gives the same results and it may be that 150 dpi might as well.
Thanks, Ray, for the tips. None of the files would work at 300 dpi (that's also from Marcos on the cluster), and 3 of the 4 won't work at 150 dpi either, but they all do for 72pt. I added some code for changing the page scale a few weeks ago for scaling paths; they can probably be hooked up to the page dimension.
The sample files now render correctly by pxlcolor at 300 dpi.