tyFlow's resolution is limited by Max SDK's viewport DIB functions....the exposed API doesn't seem to allow resizing larger than a maximized viewport size, which is why I rely on bilinear upscaling for anything larger than that, hence the blurriness.
I tried the Grabviewport script....it just returns a 100% black image for me when I choose a large resolution. Looking at its code it's using the maxscript viewport DIB function, which I believe is equivalent to the SDK function I'm using...so it's strange that you're getting sharp results with very large resolutions. Either way, have you tried modifying the script to simply bypass the resolution restriction? It seems like an arbitrary restriction that you could easily modify.
I tried the Grabviewport script....it just returns a 100% black image for me when I choose a large resolution. Looking at its code it's using the maxscript viewport DIB function, which I believe is equivalent to the SDK function I'm using...so it's strange that you're getting sharp results with very large resolutions. Either way, have you tried modifying the script to simply bypass the resolution restriction? It seems like an arbitrary restriction that you could easily modify.