Author Topic: Lossless compression of RAW  (Read 5533 times)


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Lossless compression of RAW
« on: June 04, 2013, 09:21:55 AM »
I just came across these guys.
Rawzor uses lossless image compression to compress camera raw images with zero loss in image quality or meta-information. Save up to 20% to 60% space, totally lossless. Get back the exact raw file, every byte of it. Compress your photos with absolutely no change in the original raw file.
Would it make any sense even thinking that the Camera's CPU would be fast enough to use this sort of compression and empty the buffer in time, so higher quality could be saved to SD cards? (As an alternative to the in camera 10 bit/12 bit conversion(is it a dead end?) or MJPEG conversion)?


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Re: Lossless compression of RAW
« Reply #1 on: June 04, 2013, 10:28:28 AM »
Compression of the Raw data via DNG compression or other complicated routines isn't going to happen afaik.  Not for the foreseeable future anyway.

There was some discussion about using the JPG encoder in camera, and well, a1ex didn't say it was a stupid idea (like some of my others ;)), so I guess there might be hope at some stage.

There's still some work to be done on polishing the current implementation though.  So we should give the devs some time to catch their breath.


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Re: Lossless compression of RAW
« Reply #2 on: June 05, 2013, 05:36:15 AM »
Couple thoughts... I am going to venture a guess that the cheaper/older cameras with single processors aren't going to be powerful enough to apply compression to RAW. At least from how I understand it, right now there isn't a way to prevent the system from running the h.264 compression even though the ML is storing just the RAW. That could be wrong though, and if it is, I wonder how hard it would be to use the processing power that was used for h.264 to do some sort of compression like CinemaDNG RAW.

Second thought, given that the Txi's are limited to 21mb/s at the controller even though they support UHS-1 SD cards, the maximum resolution for continuous recording (if/when they can work it out so that we can record continuously to fill up the card without stopping) would be 960x540, which is 20.4MBps. The only way we'd see 1280x720 or God forbid 1920x1080 is if some sort of fast high compression could be applied, which of course we don't want h.264, so it's doubtful any sort of RAW compression with lossless will get us there if it's even possible. It would be amazing if we could get 1280x720 continuous (24fps) out of the txi cameras with something like CinemaDNG for storage. I'd even settle for DNxHD compression, which would yield far better results than h.264 but not quite as good as RAW.

The fact that we're even able to talk about this is beyond impressive.