Friday 26 January 2007

Shadows and Highlights

Its funny how some commonly used terms are so rarely actually defined. For a forthcoming blog, I was trying to find a link on the new-fangled world wide web thingy to explain the term "Shadow Detail". Well I couldn't find a definition of the term anywhere, so I decided to write one myself!

It may not be exactly right, for all I know, but it's the definition I use:

One of the things photographers are always banging on about is "shadows" and "highlights". Now I may be a bit dim but when I started photography I couldn't work out how you knew which bits were the shadows, if you couldn't see the light source & direction.

Well it turns out that by "shadows" & "highlights" they are referring to the dark stuff & the light stuff. In a black and white photo the ultimate shadow is pure black and the ultimate highlight pure white. The area between is cunningly known as the "mid-tones".

With A brightly lit piece of coal on a sheet of white paper, the coal is the shadows, the paper is the highlights and if the light casts a grey shadow onto paper then that could be a mid-tone. How dark a highlight has to be before it becomes a mid-tone, and how dark a mid-tone has to be before it becomes a shadow...who knows!

The middle right-hand side contains the shadows,
the chrome is a highlight and some of the wood is a mid-tone.

(Click to view large)

Shadow Detail

Now one of the things photographers like to go on about a lot is "shadow detail", this is where you can see details in the darkest areas of your photograph, as opposed to the area just appearing as pure black. Generally, shadow detail is a good thing as it adds realism and depth to the image.

It is often possible to recover lost shadow detail in Photoshop though it is usually best to avoid losing it in the first place by correctly exposing the image.


At the other extreme are the highlights, these are the brightest areas of your picture. At the extreme end you have pure white, which is fine if you wanted bright white, if not these are "burnt out" highlights. The problem with burnt out highlights is that they contain no information,at all and no amount of tweaking and adjustment in Photoshop will get them back.

ND Grad filters are often used to avoid burning out the sky in landscape photography, alternatives involve blending bracketed exposures in photoshop or another package.

Getting the exposure of a shot right is often a balance between blocking up the shadows and burning out the highlights. Generally its best to err on the side of blocking up the shadows rather than over-cooking the highlights.

Why not checkout my crash guide to exposure or this highly recommended book.

If you have a better definition of these terms, I would love to hear them. Please comment or drop me an email.

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