Raw Vs. JPG

[Ronnoco]

The RAW file is the 12-bit per colour per pixel image as it came out of the camera sensor, plus individual adjustments that have been made. When you modify the ajustments you are only working on the adjustment itself, not the basic signal. You can always go back later and change it.

Not quite correct! The RAW file comes out of the A/D converter, not directly out of the sensor. When you do the modifications you are not only working on the adjustment itself, either. Exposure adjustment affects colour, noise, detail and tone. Making matters worse, the adjustments are global which means that you have to balance highlights and dark areas.

The JPG is the final compressed 8-bit per colour per pixel image. Not only have you less data than with RAW, any changes are permanent and cannot be undone. .

That is not quite true either. Most photographers just save the original and the modified version separately, but only if there is a need to. Changes don't need to be undone because you always have your original and perhaps more than one modification if you are in doubt.

For example, imagine you convert an image to black & white, then the week after you decide you preferred the colour version better. In RAW you just undo the change that gave you black and white and hey presto you have a colour image again. In JPG when it's gone it's gone..

Converting is not really the ideal approach to black and white anyway, because it does not give you the appropriate tonal quality. You should be working from the beginning either totally in colour or totally in black and white. And if you have erased the original jpeg then it was your bad decision.

Ronnoco