shooting raw

Started Feb 7, 2013 | Questions thread
John King
John King Forum Pro • Posts: 14,941
RAW, JPEG - bit depth and data loss from using JPEGs

SergeyGreen wrote:

I don't know if it changed with the most recent Olympus cameras, but as I remember there was not much you could get out of the raw files then what already was in the straight out of camera JPGs. To the exception of the WB of course. The only motivation left was in learning. Unlike with the other maker, where RAW is everything, and JPG is for no apparent reason just there :).

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I have edited both RAW and JPEG pairs of files from Olympus dSLR cameras from the E-500 onwards, and can state categorically that this is not the case.

I have never come across a RAW/JPEG pair (shooting the JPEG in LSF or SHQ mode), where I could not get a noticeably superior result from the RAW file, without even any particular difficulty.

Yes, the Olympus JPEG engine is a pearl compared with some, but simple arithmetic shows that this often repeated statement is not accurate for a number of reasons:

1) even shooting the JPEG using the relatively large and symmetrical aRGB colour space, this colour space is deficient in highly saturated colours. The sRGB colour space is just small and defective, even when compared with aRGB. sRGB is the colour space of the Internet, which should tell us all something about the images we are looking at on the Internet ...

2) OoC JPEGs have been processed in arguably the worst place in the world to do data processing - inside a digital camera. It has neither the CPU power, nor the battery power, to do the sort of processing that even a slow desktop or laptop has available to it. The fact that they can achieve such a relatively good result under such inauspicious circumstances is a tribute to the intelligence and cunning of the s/w engineers ...

3) OoC JPEGs are doomed to an 8 bit colour space. This is 2^4 smaller than what can be represented in a 12 bit colour space; even leaving aside the difference in the actual data storage methodology and modelling for RAW and JPEG files on the memory card.

4) An OoC JPEG has its WB, colour space and bit depth set irrevocably in camera. They cannot be altered in PP without incurring massive data loss in the PP image file.

5) JPEGs are compressed (in many different ways ... ) in a manner where a lot of data is lost. Even using the 2.7:1 compression that Olympus uses in-camera, this compression figure gives some idea of the fine detail in resolution and colour that is lost. Add to that loss the data lost through using an 8 bit colour space ... This lost data is irretrievable.

These are merely some of the many reasons why this canard is not merely somewhat incorrect, but outright wrong, regardless of the camera make or model.

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Regards, john from Melbourne, Australia.
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