jpg histogram exposure

Started Apr 29, 2007 | Discussions thread
gkl
gkl
Senior MemberPosts: 2,079
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exposing to the right is critical
In reply to old_dog, Jun 22, 2007

old_dog wrote:

One of the problems with digital cameras is the "noise" that can
show up in the darker portions of the image (left side of the
histogram). Here is an article that discusses the cause of this
and the concept of shooting to the right to compensate:
http://www.ronbigelow.com/articles/exposure/exposure.htm .

This is a really crucial aspect of understanding how to get the most out of a digital camera. Here is another link which explains the reason for exposing to the right:
http://www.luminous-landscape.com/tutorials/expose-right.shtml
and another which discusses histograms:

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

This applies to both RAW and jpg shooting but, as has been pointed
out, blown highlights (per the histogram) are a much bigger factor
with jpg than RAW. With jpg, try not to shift to the right so far
that you loose highlights.

Jpeg conversion does a nonlinear mapping of the data using a tone curve. Information in the dark and bright tones get compressed, and some of the tonal differentiation contained in the (linear) RAW file is lost.

With RAW, the image has a lot more
captured data than the histogram shows (I beleive it is a histogram
as the camera would interpret the image if shooting jpg) and the
information can be recoved during post processing.

A live histogram is based on RAW data, whereas the review histogram is based on the jpeg. As you say, the main advantage of RAW is the ability to adjust the exposure (levels) or the tone curve, without causing posterization or the loss of further information. cheers, gkl

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