True-colour image and video storage uses a gamut fairly close to human colour perception. However, there are various situations where this is unnecessary and others where it won't make much difference. Presumably, storage space and processing power is wasted when this happens.

An older option exists, akin to the two-colour Technicolor process, using a red-green colour space with no blue. Now, i'm not the sharpest tool in the box when it comes to image compression algorithms, but it seems to me that this option could be more efficient and applicable to certain situations.

JPEGs and presumably also MPEGs don't store colour information as RGB, and clearly that saves space. If only red and green information were stored, that would be a third smaller than RGB. It could be made a third if each of those channels were reduced to four bits. I would like to know if a similar reduction in size could be made using conventional image and video compression algorithms.

This does have applications. For instance:

* Two-colour technicolor films could be stored in a format which throws away all the blue because there is no blue in those films.

* It would make, well, shall we say, images of bare flesh less detectable because the data would look different to a fleshtone detection technique.

* It would be possible to store CGA images in a smaller format - yes, that's very much a minority application.

* It could be used as an image processing technique to make video or photographs look "quaint", rather like the sepia filter on raster graphics editors.

* It would be possible to display the images using two grey-scale monitors, two filters and a half-silvered piece of glass, or a cheaper projection TV system.

* It would continue to be possible to print colour images using an inkjet cartridge with no blue left.

* Image and video files would be smaller and there could be a trade-off with resolution.

The red-green colour blind could use a similar technique to avoid the hassle of a wasted channel.
-- nineteenthly, Dec 04 2010

Well, it would mean no need to generate blue, which has certain positive repercussions.
-- nineteenthly, Dec 04 2010


Thanks [bigsleep], i'll try that. I'm aware of an optimisation in JPEG but am not convinced this wouldn't also help. I need to know more. I did get rid of the blue channel on a JPEG before i posted this and the file ended up bigger, but i should've done it from a lossless original.
-- nineteenthly, Dec 04 2010



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