Simply, my request is for more postprocessing-type filters, for more image-quality enhancing purposes, and with more control over them.
Video from noisy analog sources and low-quality digital copies can be improved using filters. VLC supports postprocessing, but there is very little user control over it (your pick, 0 to 6), and it may not address issues specific to a given video file. VLC can alter video being displayed, but the features seem limited to modifying the image with either basic settings (contrast, saturation, etc) or adding distortion (adding noise, waves, etc). VirtualDub has a large library of filters available that can improve the image from low-quality (or low fidelity) sources, like the DotCrawl Comb Filter for NTSC and the fxVHS filters for digitized VHS. Of course, VirtualDub is not intended as a media player, and despite being an advanced tool, it doesn't work well as a general media player. VirtualDub's VDF filter files could be made compatible with VLC somehow (VirtualDub is OSS), or VLC could have its own similar filters. Computers are fast enough now to do the processing in realtime, and integrating this feature into VLC would eliminate the need for reencoding media (usually a lossy conversion) with filters set to permanently remove the noise and unintentionally remove fine details that look like noise.
If this functionality already exists, or if VLC can already use VDF filters, then I apologize for the thread, and this feature request turns into a request for documentation of the feature and easier access in the GUI. Thanks for reading this through!