[QUOTE=Michael;8943]Jon: I know that you have previously posted printing large piezography prints (24x24 or 24x30) from iPhone capture with 180 dpi or even 120 dpi and being very satisfied. Have you ever run any tests to determine the lower limit of dpi for piezography prints, i.e., where there are obvious visible signs of pixelation or other artifacts? Or is the answer really up to the photographer to determine what they are looking for in their final print?[/QUOTE]
We’ve been fortunate to work with some very smooth low resolution files. And we have printed to 90dpi on some images that were destined for exhibition.
On the other hand, we have been sent 500+MB files that were horribly prepared by over-sharpening and with poor masking lines and defects from resampling filters that absolutely fell apart when printed.
The moral is that with images where the histogram is not jumpy - you can get away with lower res. And with high res files in which less skill was used to image them - they can fall apart quickly.
The iPhone apps do imaging just after the time of exposure. Much of it is just at the limit - but not over. So Hipstamatic filtering survives the test at their maximum of 2400 or so pixels.
A lot really depends on how you image and adjust your images. If you interrupt the smooth tone and make it jumpy it will print jumpy. If you do not - it will be difficult to see the pixels until sub 90 - maybe even lower.