Raw v. Jpeg again

Revisiting the raw v. jpeg debate, a key difference is that the raw file is what the sensor captured without any processing (other than some compression, if selected) being applied whereas a jpeg (or TIFF) is what the camera itself post-processed from the sensor data in accordance with various camera processing settings. The preview on the camera shows you the embedded jpeg preview in the raw file if you are reviewing a raw shot, and that includes application of the picture control camera settings. If you are reviewing a jpeg shot, you look at that of course.

In the case of Nikon, if you review and/or process the raw files using Nikon software on your computer, then you see the raw file with the same camera settings as were set at the time the picture was taken (a profile reference is embedded in the raw file) but you can switch to an alternative profiles. None of the other major raw processes (including Adobe Camera Raw – until ACR 5.3, when Adobe reverse engineered a reasonable approximation) can understand and apply the Nikon picture control data to the best of my knowledge because Nikon have been somewhat secretive in the encoding of it (even changing the encoding between recent models) of the profiles. If you post process using non-Nikon software then you work from the basic raw data and whatever profile the processor has built in (or selected) and then make changes you want.

Obviously, we can not apply an alternative picture control profile to a JPEG or TIFF file from the camera, as the original data has already been processed and lost.

As far as I can tell, it is the same for Canon except that they have been more forthcoming with their profile data formats so that other raw processors can read them. Ditto Sony.

In addition, if you shoot raw and intend to process you are probably working in the AdobeRGB colour space rather than the sRGB colour space, which is what the display on the back of the camera operates in. (The cameras are generally at least slightly better in their overall gamut footprint than sRGB.) I am not sure therefore that reviewing a raw file on the back of the camera that has a sharpening filter applied is especially informative – in fact, isn’t the display really mostly useful for looking at the histograms?

Regarding sharpening (once of the picture control settings), note that this is usually the last or nearly last step in the post-processing workflow. So, although I would set it for JPEG or TIFF images produced by the camera, and, in the case of raw files, may want to preview it when originally viewed on my computer before commencing post-processing, I would remove any sharpening until I had finished other post-processing work.

Useful thread on flickr: http://www.flickr.com/groups/nikon_d300_users/discuss/72157605667434167/ (especially contribution from intrHawk

Posted via email from kyber’s posterous

Leave a Reply