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Old 18th February 2018
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Re: Lens Corrections?

Originally Posted by PeterBirder View Post
You cannot ever view a raw file (raw not RAW files as wraw is not an acronym, it literally means the raw data from the sensor) or apply any type of correction to it, it has to be "developed" or decoded into a form such as JPEG which can be displayed first.
I know why you say this Peter, but it's not quite as simple as that. Any file portending to represent image data has to be processed to be viewed. Even a BMP file, which is probably the nearest to a pixel map as you'll find, has all sorts of meta data and formatting in it. JPEG files are complex structures that have varying levels of compression and fancy encoding in them and need to be read by special programs to turn them into an image on a screen or printer.

In that sense then raw files are just another format and need to be interpreted to be displayed. Recent versions of Mac OS actually have raw file decoding in the OS so no additional software is needed.

The key difference between raw and JPEG of course is that the raw data has has a lot less processing done to it in camera. In particular, there is no WB, sharpening, tone curve, NR, shadow/highlight processing, vignette correction, CA correction, geometric distortion correction etc etc. That's the huge benefit of raw of course since all this can be done later on the PC. No amount of post processing can easily undo sharpening halos for example.

Note though that raw files are invariably pre processed to some degree - it's not just "raw data of the sensor". Fuji bake NR in, Sony do data hidden compression (e.g. the famous " star eater " bug), Olympus can add corrections without you realising (e.g. "shading correction" finds its way into raw files unless you turn it off).
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