I think it is safe to say that the most important part is to be consistent between what you train on and what you infer against. However, it could be that one of the color spaces is more amenable to training. To my knowledge, that has not been completely ruled out. Indeed, it seems supported by your claim that they can get a tiny bit more efficient with some spaces.
That said, this post is my long winded way of asking if you have links on that. :)
Also, the nature of the inference may not require high fidelity raw images since they're going to be down-sampled anyway. Unless research suggests that raw images improve inference metrics, nobody's going to invest effort into building a raw image dataset. One notable recent exception to this is the "Learning to see in the dark" paper on low light image enhancement[1] - they found that training on raw images gives much better enhancement than JPEG.
The data availability problem may start getting solved in the near future because mobiles (atleast Android) support storing and processing raw images, and on-device learning and inference capabilities are getting better all the time on mobiles.
[1]: https://www.youtube.com/watch?v=qWKUFK7MWvg&feature=youtu.be
> probably because most cameras, except DSLRs, don't support storing raw images
This may be true for consumer cameras but not for machine vision cameras. Most color machine vision cameras do support the Bayer format. Basler, FLIR (Point Grey), IDS and so on all support the Bayer format. If you roll your own camera you definitely have to deal with the Bayer format from the sensor you are using.
And if you do not want any compression on your data-set images the Bayer format also takes less space than the RGB format.
I'm not arguing it is a good idea, I'm just interested if it works :)
You are right about custom cameras - in fact, I have some camera modules for experimenting with surveillance, night vision and machine learning, and some of their datasheets mention registers that, when set, output Bayer format images. Machine learning in surveillance is still a rather under-serviced market, but it's potentially a rich source of raw image datasets.
Raw format training and inference definitely work. The obstacle is only data availability.
https://www.kaggle.com/c/statoil-iceberg-classifier-challeng...