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RAW vs. cRAW

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Post Options Post Options   Quote Imagery Fan Quote  Post ReplyReply Direct Link To This Post Topic: RAW vs. cRAW
    Posted: 15 August 2010 at 21:29
Is there any downside to using cRAW instead of RAW with the a900? For example, is there any loss in quality or problems in PP? Using cRAW (compressed RAW) to get more shots on a memory card seems desirable unless it introduces problems of some sort. Have there been any studies or does anyone have any experience with this?
 



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Post Options Post Options   Quote 2manycamera Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 21:34
My basic rule of thumb is: Work=RAW, Play=CRAW. If I plan to sell, I want to take no chances of limiting what I have available to work with. I know that RAW gives me the most info for PP. I know CRAW compresses that info, so why risk it if $$ is concerned? Memory is cheap, bring more cards.

This is what I do, your results may vary.
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Post Options Post Options   Quote gnatsum Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 21:38
Raw is 12 bit and CRAW is 8 bit.

You lose all the highlight recovery capabilities that 12 bit raw files offer.

If you shoot in very controlled environments and know there is no chance of some highlights blowing out, then shoot CRAW if you wish.

I tried shooting CRAW for a few months this year, and really it was not worth saving space for losing pictures to blown out highlights...
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Post Options Post Options   Quote pubetter Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 21:47
Wau, this is news to me... after getting A850 I started shooting cRAW - without knowing or testing the difference. Damn. Or because it can get even better!!
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Post Options Post Options   Quote kiklop Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 22:01
A point to keep in mind is that the software (raw converters) is improving over time. IF we really care to have the best data for the future we can, we should use RAW instead of cRAW even if our current processing workflow may not be capable of showing the difference (and believe it or not, most popular raw converter today come with compromises intentionally made to increase speed of processing .. an issue that may not be an issue relatively soon) .
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Post Options Post Options   Quote jdsin Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 22:14
Thanks all....as the new owner of an A850 I was about to ask the same question....
 



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Post Options Post Options   Quote frankieg Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 22:30
Originally posted by gnatsum gnatsum wrote:

Raw is 12 bit and CRAW is 8 bit.

You lose all the highlight recovery capabilities that 12 bit raw files offer.

If you shoot in very controlled environments and know there is no chance of some highlights blowing out, then shoot CRAW if you wish.

I tried shooting CRAW for a few months this year, and really it was not worth saving space for losing pictures to blown out highlights...


Now this is news to me. If it is true and backed by some documentation I'd like to see it. I do know we had a big discussion a while back concerning this and the consensus from software engineers who were familiar with the craw algorithm for compression was that it was "effectively" lossless. There was no mention of 8 bit vs. 12 bit files. I'm not sure if that equates to 8 bit vs 12 bit resolution. You can have files broken up into any size data words and it makes no difference to data integrity just efficiency in handling.

Another point you mush understand is that just because something is compressed it does not mean data loss. Zip is lossless compression and when used on RAW files it compresses to about the size of a CRAW file.

So I respectfully ask if this is an opinion or and observation or fact derived from detailed documentation. Opinions as well as observations can be misleading clear manufactures documentation generally is better to base statements like that on.

If true, thank you very much and I am changing to RAW as I always shoot in extreme conditions you mentioned.
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Post Options Post Options   Quote Fuzzphoto Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 23:04
@gnatsum: cRAW is most definitely 12 bit. Do you have even so much as a shred of proof about your claim?
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Post Options Post Options   Quote Göran Larsson Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 23:12
Originally posted by gnatsum gnatsum wrote:

Raw is 12 bit and CRAW is 8 bit.

no.no.no.
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Post Options Post Options   Quote Fuzzphoto Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 23:42
Find this quote from Dyxum member "my-spot" who developed RAW processing software:

Technically speaking... cRAW is not Lossless. One clue to this is that it is a "fixed" length format. 16 (12 bit) pixels are always stored in 16 pixel/16 byte packets that use a very "different" compression algorithm. It is decompressed into 12 bit data (16 pixels = 24 bytes).

However, From what I can tell, the compression used will, in fact, be Lossless 99.9% of the time, and in the 0.01% that it is lossy, you will never see the difference. CMS conversion, Bayer demosiacing, conversion to 8 bit formats, and (if used) jpeg compression, will have a MUCH bigger effect on the final output then cRAW compression would ever have.


Thread is located here

So the data loss is estimated to be .01%
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Post Options Post Options   Quote OldClicker Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 23:51
Originally posted by Fuzzphoto Fuzzphoto wrote:

Find this quote from Dyxum member "my-spot" who developed RAW processing software:

Technically speaking... cRAW is not Lossless. One clue to this is that it is a "fixed" length format. 16 (12 bit) pixels are always stored in 16 pixel/16 byte packets that use a very "different" compression algorithm. It is decompressed into 12 bit data (16 pixels = 24 bytes).

However, From what I can tell, the compression used will, in fact, be Lossless 99.9% of the time, and in the 0.01% that it is lossy, you will never see the difference. CMS conversion, Bayer demosiacing, conversion to 8 bit formats, and (if used) jpeg compression, will have a MUCH bigger effect on the final output then cRAW compression would ever have.


Thread is located here

So the data loss is estimated to be .01%


That is not what he said. He said that it you would be able to see the difference 0.01% (not that he intended this as a real number, just very small) of the time. He says nothing about the quality of that 1 image out of 10,000. - TF
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Post Options Post Options   Quote Davey Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 00:07
This was also my understanding, and consequently, I've shot cRAW for pretty much everything.

I did dozens of side-by-side comparisons and could not see any difference in IQ between the two image files.

If cRAW is 8-bit, I would definitely switch back to RAW, but I haven't see this stated anywhere ever before.


Originally posted by frankieg frankieg wrote:

Originally posted by gnatsum gnatsum wrote:

Raw is 12 bit and CRAW is 8 bit.

You lose all the highlight recovery capabilities that 12 bit raw files offer.

If you shoot in very controlled environments and know there is no chance of some highlights blowing out, then shoot CRAW if you wish.

I tried shooting CRAW for a few months this year, and really it was not worth saving space for losing pictures to blown out highlights...


Now this is news to me. If it is true and backed by some documentation I'd like to see it. I do know we had a big discussion a while back concerning this and the consensus from software engineers who were familiar with the craw algorithm for compression was that it was "effectively" lossless. There was no mention of 8 bit vs. 12 bit files. I'm not sure if that equates to 8 bit vs 12 bit resolution. You can have files broken up into any size data words and it makes no difference to data integrity just efficiency in handling.

Another point you mush understand is that just because something is compressed it does not mean data loss. Zip is lossless compression and when used on RAW files it compresses to about the size of a CRAW file.

So I respectfully ask if this is an opinion or and observation or fact derived from detailed documentation. Opinions as well as observations can be misleading clear manufactures documentation generally is better to base statements like that on.

If true, thank you very much and I am changing to RAW as I always shoot in extreme conditions you mentioned.
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Post Options Post Options   Quote roweraay Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 04:40
Originally posted by Kiklop Kiklop wrote:

A point to keep in mind is that the software (raw converters) is improving over time. IF we really care to have the best data for the future we can, we should use RAW instead of cRAW even if our current processing workflow may not be capable of showing the difference (and believe it or not, most popular raw converter today come with compromises intentionally made to increase speed of processing .. an issue that may not be an issue relatively soon) .


Exactly the logic I follow. I always use RAW and never cRAW in my A900. Of course in the consumer Sony cameras (other than the A700/850/900), what they call as "RAW" is really cRAW masquerading as RAW, IMHO. So if a camera offers full-RAW, why compromise ?
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Post Options Post Options   Quote Fuzzphoto Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 08:01
If the difference is both negligable and invisible, why use larger files?
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