I'm having trouble with getting decent-quality interpolation when downscaling hi-res JPEGs and TIFFs (source is either full or cropped photo from 3000 x 2000 from Nikon D70 or approx. 5800 x 3700 from Nikon slide scanner) to a Jitter output that is arbitrarily smaller, such as 720 x 480 for DVD or 1024 x 768 for computer display. (For the sake of being complete, I'll also say that there will also always be subsequent compositing operations with other downscaled photos or portions thereof.) I'm a Jitter newbie, but in my experiments with jit.matrix so far, turning on the interpolation option (per Jitter Tutorial 14) does little to eliminate the jaggies when scaling the image down to a smaller jit.matrix and subsequent jit.window. I seem to get the same results whether I use a "read" or "importmovie" command at the front end. I've just started to look into the GPU processing, but am still unclear what provision Jitter has under either CPU or GPU for smooth interpolation when downsizing large images... hopefully something approximating Photoshop's interpolation capabilities (even if there's a tradeoff in processing time).
Any thoughts are much appreciated!