Classic HTM is designed for streaming data, not static data. So naturally you wouldn’t pass it an image with 50 cars… you would pass it a series of images over time, in which 50 cars passed by a camera.
Of course, it depends on the use case. This wouldn’t be useful for anomaly detection of vehicle frequency either if you were to try monitoring a busy highway where every frame always had cars in it.
And again, this was a demonstration for one easy way of linking HTM with classic AI algorithms using word SDRs. One could imagine a slightly different system which uses classic image AI to locate things in video frames, and then have both subjects and positions to do some streaming HTM magic with. Or an audio AI for identifying animal calls hooked up with HTM to detect population anomalies in a particular habitat, or tracking migrations, etc.
Also, just to be clear, image2sdr is not meant to be biologically plausible. It is just another tool that some people may find useful for a few AI / HTM related cases. There are probably many other tools that could be applied to many of the same cases.