shooting raw

Started Feb 7, 2013 | Questions thread
John King
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Re: RAW, JPEG - bit depth and data loss from using JPEGs
In reply to pris, Feb 13, 2013

Gidday Pris

pris wrote:

John King wrote:


4) An OoC JPEG ... cannot be altered in PP without incurring massive data loss in the PP image file.

We've been over this a while ago... This part is most certainly incorrect - they sure can be put through major postprocessing surgery with massive color and tonality changes, while preserving detail and remaining noise free, and last time we discussed this I posted examples of such changes. These techniques are far beyond small corrections most know and use, one needs to know what one is doing in PP.

Try doing a 2,000°K WB adjustment to any JPEG file. According to the histogram, between 1/3 to 1/2 of the data points are lost. This may not matter all that much, depending on your use of the file. It usually matters to me.

However, if the file has a WB of (say) 4,000°K and it should have been around (say) 2,200°K and has been taken in a dark environment - e.g. inside a church during a wedding, the data loss is far more visible, even just viewing it on a monitor. Might be OK for small prints, but forget about printing at A3 or above ...

I also don't like making work for myself. If I cannot get the results I want/need to print at these sizes within a minute or two at the outside, I swear at myself for not taking the picture properly in the first place; and move on. No way that I am going to spend 30-90 minutes trying to turn a "sow's ear" shot into a hero shot, even if I could.

Same with cropping. I always aim to get the image I want composed and exposed as correctly as possible in the camera. If I don't ... 1) it's my fault; and 2) it's an admission of failure on my part.

Ansel Adams called it pre-visualisation. I strive to achieve that with almost all photos I take, even just happy snaps. They are all good practice for when it really, really matters. Just IMHO, of course.

I am a great believer in the "less is more" school of PP. If one can tell that the file has been touched, one has gone too far, IMNSHO.

Also, what I said was with particular reference to the statement that "... 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 ... ", and as such, needs to be understood within that context.

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