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RAW vs. cRAW

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Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Topic: RAW vs. cRAW
    Posted: 17 August 2010 at 05:11
Originally posted by gnatsum gnatsum wrote:

Wow, I have no had the time to read this thread and didn't realise there were so many stern cRaw zealots around looking for shreds of evidence and documentation approved by the all correct photography authority.


gnatsum, before accusing others of being zealots without even reading the whole thread it might be more appropriate to explain where your conclusions that cRAW is 8 bit and looses highlight headroom is coming from. From everything else I've read both of these statements are not correct.

cRAW is lossy (to what extend is another matter) so if you want to play sure and not loose anything shooting RAW is probably the only way to guarantee that. If you're happy with the current cRAW quality and don't need anything more in the future cRAW will save you a lot of storage space. So there is no right answer, it all depends on your requirements. For me as a hobby photographer I've determined cRAW is good enough but I can understand people preferring RAW for the reasons mentioned in some posts of this thread.

Edited by pegelli - 17 August 2010 at 05:27
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Post Options Post Options   Quote evangelos k Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 04:43
Originally posted by Vivec Vivec wrote:

Hi Gnatsum,

Relax, no-one is being a 'zealot' here -- different opinions and viewpoints is what makes Dyxum a lively place

Originally posted by gnatsum gnatsum wrote:

I'm a photographer and I shoot photos.


That's cool -- and you are right: whehter using craw or raw is probably not going to matter for the photo.

Originally posted by Gnatsum Gnatsum wrote:

cRAW DEFINITELY does NOT have the same highlight headroom as a full raw image and it is not possible to pull highlights as much as with a 12 bit raw.


I respectfully disagree here; read my earlier post for the details: cRaw can accurately represent the highest highlights and darkest darks. The only case where a potential loss of precision occurs in a (super) high contrast range within 16 pixels with subtle hues. But even there, the loss of precision is minimal.

Anyway, I have made my points. Everyone can have their own viewpoints and should use what they feel best about -- photography should be fun


cRAW it is then! That's what you said, right?

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Post Options Post Options   Quote Vivec Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 04:27
Hi Gnatsum,

Relax, no-one is being a 'zealot' here -- different opinions and viewpoints is what makes Dyxum a lively place

Originally posted by gnatsum gnatsum wrote:

I'm a photographer and I shoot photos.


That's cool -- and you are right: whehter using craw or raw is probably not going to matter for the photo.

Originally posted by Gnatsum Gnatsum wrote:

cRAW DEFINITELY does NOT have the same highlight headroom as a full raw image and it is not possible to pull highlights as much as with a 12 bit raw.


I respectfully disagree here; read my earlier post for the details: cRaw can accurately represent the highest highlights and darkest darks. The only case where a potential loss of precision occurs in a (super) high contrast range within 16 pixels with subtle hues. But even there, the loss of precision is minimal.

Anyway, I have made my points. Everyone can have their own viewpoints and should use what they feel best about -- photography should be fun
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Post Options Post Options   Quote gnatsum Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 03:31
Wow, I have no had the time to read this thread and didn't realise there were so many stern cRaw zealots around looking for shreds of evidence and documentation approved by the all correct photography authority.

I don't know about some of you guys but I'm no lab monkey so I don't conduct misleading controlled tests that are designed to prove my points. Nor do I like to write dissertations on digital sensor science.

I'm a photographer and I shoot photos.

And if there's one thing that I know about RAW vs cRaw is this:

Firstly unless you have a 12 bit display, no one is viewing a 12 bit image.

When we shoot raw, we have 12 bits data, most of which cannot be viewed at the same time, unless we compress the data, by lifting shadows and pulling highlights.

cRAW DEFINITELY does NOT have the same highlight headroom as a full raw image and it is not possible to pull highlights as much as with a 12 bit raw.

Don't kid yourself that you are viewing a 12bit jpeg after you edit your raw. And 16 bit tiff, wow unless you are loaded and can afford a screen that displays 16 bit images, don't even go there.

craw essentially has the same dynamic range as a jpeg.

14 bit raw takes it to an even higher level where there is immense dynamic range, again, not all viewable at once, but much more can be captured in a single raw file, to be compressed into a viewable 8 bit jpeg.

Your only other option is to take many 8 bit jpgs and make an HDR. but then you still just have 8 bits.

Sorry I didn't pass my phd so I can't back all that up, but feel free to show me your own shreds and documents.

If you don't like what I have to say then you can skip my post and call me a fool. but try shooting a scene one day with craw and then raw and compare your highlight headroom.
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Post Options Post Options   Quote roweraay Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 03:30
Originally posted by Vivec Vivec wrote:

Originally posted by Shatun Shatun wrote:

I do remember the mp3 inovation time. At that moment a lot of people told that there is no differences and they loafing from others who told that they could hear the difference. The same I can say about Dolby True HD and lossy Dolby Digital. A bit wrong comparation between sound and image but I hope it helps to show my opinion.


Thanks for the good discussion Shatsun. However, I don't agree with the MP3 comparision. Technically, it is clear that MP3 is lossy, and as such it is much more close to JPG for images. cRAW is harder to compare: it is algorithmically almost loss-less and much closer to lossless compression like the huffman used in DNG. If there is some loss of precision, it is hard to quantify how much this is visible since only some precision is lost which (in my opinion) will always fall within the noise.



All good arguments but the point Kiklop made earlier was a very pointed one, which I am fully in alignment with.

What he stated is that CURRENT RAW converters are unable to notice much of a difference between the output from the RAW and cRAW, but that might change in the future, with significantly more sophisticated RAW processors on the way. So when those RAW processing engines with much higher capabilities become available, having the best possible raw material to work with, would be a big plus than having a compromised (however close to the original it may be) version.

The best possible file version currently available, is RAW and not cRAW or JPEG or any other format. Bottomline, if you absolutely want to save a few MB of space per file, then go ahead and continue to shoot cRAW but if that extra space is not such a heavy lift, then just go with RAW....there are no downsides to shooting RAW, is there ?
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Post Options Post Options   Quote Vivec Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 02:32
Originally posted by Shatun Shatun wrote:

I do remember the mp3 inovation time. At that moment a lot of people told that there is no differences and they loafing from others who told that they could hear the difference. The same I can say about Dolby True HD and lossy Dolby Digital. A bit wrong comparation between sound and image but I hope it helps to show my opinion.


Thanks for the good discussion Shatsun. However, I don't agree with the MP3 comparision. Technically, it is clear that MP3 is lossy, and as such it is much more close to JPG for images. cRAW is harder to compare: it is algorithmically almost loss-less and much closer to lossless compression like the huffman used in DNG. If there is some loss of precision, it is hard to quantify how much this is visible since only some precision is lost which (in my opinion) will always fall within the noise.

 



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Post Options Post Options   Quote Vivec Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 02:28
Originally posted by Shatun Shatun wrote:

Originally posted by Vivec Vivec wrote:

Oh, not a again

Short version: images in cRaw are for all intent and purposes equal to Raw images. I can confidently predict based on the technical format, that no-one will ever produce a 'realistic' photo where the difference can be noticed, and I don't think anyone can even produce an 'artificial' photo to show the difference.

As a consequence, cRaw is clearly preferable to Raw since the files are much smaller. FPS is potentially higher than in Raw since the data-pipeline is the bottleneck, the compression on cRaw is extremely fast. Note, that after expansion, we have 12-bit Raw file again, so in lightroom and photoshop you work in the full color space.

I believe that the only reason we also have the Raw format is to prevent bad press from 'not having full raw' fanatics.

----
cRaw divides the image in 16 pixel groups, and stores the maximum and mininum pixel in each group as 11-bits. This is a 'loss' of 1 bit but since it is on the maximum and minimum, this is below the normal noise of the sensor, bayer array, etc. The other 14 pixels are stored as a 7 bit number that gives the relative color with respect to the minimum and maximum value. If the difference between the minimum and maximum is lower than 7 stops, than this is exact (no loss). If it is higher, there is a potential loss of precision of up to 4 bits. (not 5 since we can round). However, in a such a high-difference range (very bright to very dark) there is already a big loss of fidelity on the sensor level, bayer filter, etc. So, even that loss is technically within the 'noise' level anyway.

All in all, cRaw is a very smart and efficient (nearly loss-less) encoding of Raw files. For almost all images, there is no difference at all with the Raw file. And based on the technical algorithm, I agree that there will be perhaps 1 in a 10.000 images where a difference might perhaps be noticable -- perhaps

---
btw. I think cRaw is also preferable to the DNG format since DNG files do not always preserve the 'makernote' correctly. In particular, the recent Sony lens information block is not preserved. See more info about this in this thread post



Agree, not again, but happened. :)

I do not agree that 11 bit in best case is the same as 12, I do not agree that there is no differences especially on 24MP printed in big format, but at the same time I do believe that it is almost impossible to see differences. And I do not agree that cRAW is preferable over DNG or RAW. If somebody has a lot of storage then RAW is preferable. If storage is expensive then may be even jpg would be preferable for some fotographers. Regarding DNG I already mentioned that it is not perfect, but for me it is very acceptable. But any way I do agree that better to stop this discussion :)

I do remember the mp3 inovation time. At that moment a lot of people told that there is no differences and they loafing from others who told that they could hear the difference. The same I can say about Dolby True HD and lossy Dolby Digital. A bit wrong comparation between sound and image but I hope it helps to show my opinion.
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Post Options Post Options   Quote Shatun Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 21:30
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...


This is totally wrong... In best case it is 11 bits. Also it is totally wrong that highlights will be blown up (at least by cRAW format). It is no matter highlight midrange or lowlight - important that 16 pixels block will have values which won't fit cRAW range.
But unfortunately looks like only several people tried to understand format. Most try to ague about without any checks of format or even making comparations.

PS. For those who still have time I have very nice new topic: Is JPG with 100% quality settings has any visible differences as JPG with 90%
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Post Options Post Options   Quote GrahamB Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 21:19
Originally posted by Shatun Shatun wrote:

The problem is that DNG requires much more calculation power. So for big resolution and big FPS a very powerful engine should be used. Also do not forget about power consumption which will be higher for DNG and for RAW against cRAW. But I also would like to see DNG in sony alphas...


Here's a LINK to cameras that write DNG.

Graham
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Post Options Post Options   Quote darosa Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 21:15
Originally posted by Vivec Vivec wrote:

Oh, not a again


+1

Apart from gnatsum's spectacular contribution this is all old news.
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...


Please gnatsum, give us some evidence.
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Post Options Post Options   Quote Shatun Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 21:14
Originally posted by GrahamB GrahamB wrote:

As far as the difference, apparently Adobe's compression algorithm is more efficient than Sony's. What ticks me off is that Sony doesn't adopt DNG as a native format. Wouldn't it be nice to have smaller non-lossy RAW's produced in camera?

Graham


The problem is that DNG requires much more calculation power. So for big resolution and big FPS a very powerful engine should be used. Also do not forget about power consumption which will be higher for DNG and for RAW against cRAW. But I also would like to see DNG in sony alphas...
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Post Options Post Options   Quote Shatun Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 21:10
Originally posted by Vivec Vivec wrote:

Oh, not a again

Short version: images in cRaw are for all intent and purposes equal to Raw images. I can confidently predict based on the technical format, that no-one will ever produce a 'realistic' photo where the difference can be noticed, and I don't think anyone can even produce an 'artificial' photo to show the difference.

As a consequence, cRaw is clearly preferable to Raw since the files are much smaller. FPS is potentially higher than in Raw since the data-pipeline is the bottleneck, the compression on cRaw is extremely fast. Note, that after expansion, we have 12-bit Raw file again, so in lightroom and photoshop you work in the full color space.

I believe that the only reason we also have the Raw format is to prevent bad press from 'not having full raw' fanatics.

----
cRaw divides the image in 16 pixel groups, and stores the maximum and mininum pixel in each group as 11-bits. This is a 'loss' of 1 bit but since it is on the maximum and minimum, this is below the normal noise of the sensor, bayer array, etc. The other 14 pixels are stored as a 7 bit number that gives the relative color with respect to the minimum and maximum value. If the difference between the minimum and maximum is lower than 7 stops, than this is exact (no loss). If it is higher, there is a potential loss of precision of up to 4 bits. (not 5 since we can round). However, in a such a high-difference range (very bright to very dark) there is already a big loss of fidelity on the sensor level, bayer filter, etc. So, even that loss is technically within the 'noise' level anyway.

All in all, cRaw is a very smart and efficient (nearly loss-less) encoding of Raw files. For almost all images, there is no difference at all with the Raw file. And based on the technical algorithm, I agree that there will be perhaps 1 in a 10.000 images where a difference might perhaps be noticable -- perhaps

---
btw. I think cRaw is also preferable to the DNG format since DNG files do not always preserve the 'makernote' correctly. In particular, the recent Sony lens information block is not preserved. See more info about this in this thread post



Agree, not again, but happened. :)

I do not agree that 11 bit in best case is the same as 12, I do not agree that there is no differences especially on 24MP printed in big format, but at the same time I do believe that it is almost impossible to see differences. And I do not agree that cRAW is preferable over DNG or RAW. If somebody has a lot of storage then RAW is preferable. If storage is expensive then may be even jpg would be preferable for some fotographers. Regarding DNG I already mentioned that it is not perfect, but for me it is very acceptable. But any way I do agree that better to stop this discussion :)

I do remember the mp3 inovation time. At that moment a lot of people told that there is no differences and they loafing from others who told that they could hear the difference. The same I can say about Dolby True HD and lossy Dolby Digital. A bit wrong comparation between sound and image but I hope it helps to show my opinion.
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Post Options Post Options   Quote GrahamB Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 20:58
Originally posted by Shatun Shatun wrote:

It is really interesting. The only guess is LR tries to approximate or predict lost bits. But even so it is intreting why DNG from cRAW is bigger.
But one question - is it correct that both RAW and cRAW contained the same (as it possible to make) scene? Coz different level of small objects with high contrast will change DNG significantly, coz Huffman compressed files depend on content, but RAW and cRAW not (size is different due to embedded preview jpg).


I've been shooting nothing but full raw for several years, so I didn't have any recent cRAW's to compare. To have accurate examples to convert, I shot the same scene in both raw and craw, and then converted to DNG immediately before posting.

As far as the difference, apparently Adobe's compression algorithm is more efficient than Sony's. What ticks me off is that Sony doesn't adopt DNG as a native format. Wouldn't it be nice to have smaller non-lossy RAW's produced in camera?

Graham
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Post Options Post Options   Quote Vivec Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 20:51
Oh, not a again

Short version: images in cRaw are for all intent and purposes equal to Raw images. I can confidently predict based on the technical format, that no-one will ever produce a 'realistic' photo where the difference can be noticed, and I don't think anyone can even produce an 'artificial' photo to show the difference.

As a consequence, cRaw is clearly preferable to Raw since the files are much smaller. FPS is potentially higher than in Raw since the data-pipeline is the bottleneck, the compression on cRaw is extremely fast. Note, that after expansion, we have 12-bit Raw file again, so in lightroom and photoshop you work in the full color space.

I believe that the only reason we also have the Raw format is to prevent bad press from 'not having full raw' fanatics.

----
cRaw divides the image in 16 pixel groups, and stores the maximum and mininum pixel in each group as 11-bits. This is a 'loss' of 1 bit but since it is on the maximum and minimum, this is below the normal noise of the sensor, bayer array, etc. The other 14 pixels are stored as a 7 bit number that gives the relative color with respect to the minimum and maximum value. If the difference between the minimum and maximum is lower than 7 stops, than this is exact (no loss). If it is higher, there is a potential loss of precision of up to 4 bits. (not 5 since we can round). However, in a such a high-difference range (very bright to very dark) there is already a big loss of fidelity on the sensor level, bayer filter, etc. So, even that loss is technically within the 'noise' level anyway.

All in all, cRaw is a very smart and efficient (nearly loss-less) encoding of Raw files. For almost all images, there is no difference at all with the Raw file. And based on the technical algorithm, I agree that there will be perhaps 1 in a 10.000 images where a difference might perhaps be noticable -- perhaps

---
btw. I think cRaw is also preferable to the DNG format since DNG files do not always preserve the 'makernote' correctly. In particular, the recent Sony lens information block is not preserved. See more info about this in this thread post. Also, if you edit a DNG in lightroom or camera raw, the XMP edit information is stored in the DNG itself instead of as a seperate side-car XMP file which is not always preferable from a backup perspective, and from a safety perspective (ie. disk write failures).

Edited by Vivec - 16 August 2010 at 20:57
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