I'll take a shot at summarizing.

An image captured in RAW that has a histogram completely within range, i.e. no clipping at either end has captured the complete range of lighting in the scene. So bracketing is unnecessary as there are no more light values to capture.

That is why Lighthouse said "If the info is already there in the RAW you do not need HDR to bring it out. You can bring it out by other normal processing means." (The other "normal processing means" are in effect a form of HDR processing on the RAW data so that all the light values lie within the range of the JPG image produced.).


Nice summary. This makes the most sense to me (amateur). I sure hope you're right. Thank you,Ken



In camera HDR processing on the raw data does just that. It processes/squeezes the greater dynamic range of the raw capture into the narrower dynamic range of the resulting jpg.

When the range of light values in the scene exceeds what the camera can capture in RAW or JPG the histogram will show clipping of light values at one or both ends. This is when exposure bracketing is necessary to capture the whole range of light values in two, three or more images.

HDR software combines in ingenious ways the parts of each of the images that are properly exposed squeezing all the light values of the multiple images to be withing the final limited range of the resulting JPG.

This is similar to the in-camera HDR firmware squeezing the greater range of values in the RAW capture into the narrower range of values in the resulting JPG.

So,

1. Bracketing captures all the light values in the scene when one image, even RAW, cannot.

2. HDR is the software or firmware that combines and optimally translates/squeezes that great range of light values into the limited dynamic range of the resulting JPG image.

Michael