RED Data Compression Question...

[CK Olsen]

I have indirectly asked about this before, but still a bit lost on the just how much data compression is going on under the hood... From my calculations based upon what I have read here on the site, it appears that, for example, the red28 codec is roughly equal to a data compress of 10:1.

So...
for those in the know what are the actual compression rates for the various red codecs?

Thanks in advance,
Skitch

 

[Daniel Browning]

As discussed in this thread about disk speed, RED RAW is 323 MB/s, which makes REDCODE 26 approximately 12:1, and REDCODE 36 a 9:1 ratio.

Be aware that the ratio is just a novelty; by itself it doesn't indicate anything about image quality. (For example, if RED used an RGB DCT compression like most other cameras, even at 100 MB/s (3:1) the quality would be worse than REDCODE 36.)

 

[CK Olsen]

Yes, but compression is compression...

Yes, but compression is compression...

... and I am just trying to get a better handle on how much data is getting tossed out.

Yes, Red makes some really pretty pictures, but VFX is always smoother when you can acquire with the least noise possible, whether that noise comes from compression or film grain.

(Old adage around here... "Always better to Add then to Remove...")

 

[Seth Larney]

In order for the datarates of redcode to have much meaning (when talking abot how much data is 'thrown' away), you need to understand a little about the way that bayer sensors compress with wavelet and how this pertains to RAW data. Graham has done some incredibly clever things with REDCODE and all these things factor in heavily, which is why the quality of REDCODE is so high.

dbr is right though, it is between 9:1 and 12:1

 

[RivaiC]

......Graham has done some incredibly clever things with REDCODE and all these things factor in heavily, which is why the quality of REDCODE is so high.

dbr is right though, it is between 9:1 and 12:1

Who is Graham ? Are you trying to mention Graeme ?

 

[jbeale]

> Yes, but compression is compression...

Wow... I would beg to differ with that statement. There is a wide variety of compression in both type and degree, with a corresponding wide variety of effect on the output image. Of course, it also depends on your input image- the one generality I would make is that noise does not compress well, so if the input is noisy (low light) the output quality will suffer. But of course, that is true even with no compression at all.

 

[Seth Larney]

Who is Graham ? Are you trying to mention Graeme ?

Hi Rivai,

Yes indeed .. Graeme, please forgive me !

 

[Dylan Reeve]

With a VBR codec and intelligent compression, it is possible to achieve quite high compression ratios with no observable loss.

 

[Michel Hafner]

What are realistic lossless compression ratios for RAW? 3:1?

 

[RivaiC]

Hi Rivai,

Yes indeed .. Graeme, please forgive me !

I'm ok. It just that i saw Graeme with his hammer on your back. Like this :angry2: