This image required a scen with a wide range of brightness.  I chose a canal lock scene, set against the sky as there’s a reasonable range – from shadows in the lock, to the bright ends of the lock gates.  Here’s the scene:

A lock on Rochdale Canal

A lock on Rochdale Canal

As the exercise instructs, I set up my camera so the highlight clipping warning just appears.  The settings were ISO 100, 1/30s exposure and an aperture of f/16:

"Just" clipping

“Just” clipping

I then took four additional shots – increasing the exposure by one stop each time.

The next step was to review the images on my computer – comparing the various aspects of the highlight areas:

Completely lost areas of visual information

Between the first and second images there’s a clear loss of detail in the branches of the trees, with them seeming to “blur” into the sky:

Original - Tree Detail

Original – Tree Detail

Second Shot - Loss of Tree Detail

Second Shot – Loss of Tree Detail

By the final image even details in dark areas have more-or-less disappeared:

Fifth shot - complete loss of detail

Fifth shot – complete loss of detail

A visible break in the form of an edge between nearly-white and total white

Even in the first image, this is evident, where the white ladder is set against the light-grey sheds in the background – it merges with a solid block of white, with no clear form to it:

Original - Nearly-white and white edge loss

Original – Nearly-white and white edge loss

A colour cast along a fringe bordering the clipped white highlight

A “halo” of colour is actually already evident in the image above on the left-hand-side of the ladder – most obvious where it cosses the black lock gate. However, it’s even more evident in the second image – as shown below:

Second image - Colour fringe on ladder

Second image – Colour fringe on ladder

In later images it disappears, as details become blown-out:

Third image - Colour fringe gone with detail

Third image – Colour fringe gone with detail

The colour saturation

The blue sky is reasonable in the first image, but by the second image it’s los saturation and is hard to distinguish from the clouds scattered across it:

Original - sky saturation

Original – sky saturation

Second image - sky saturation

Second image – sky saturation

Overall, the image taken without any highlight clipping, at the top of this post, has a far more pleasing tone to the sky.

Using Recovery

The final part of this exercise is to experiment with the “Recovery” tool in my software.  This makes use of data from the different colour (RGB) channels to “rebuild” clipped channels – taking advantage of the fact that the different channels don’t always clip at the same time.

I noted with very high levels of recovery white areas seemed to become grey-ish and the whole image seemed duller in tone.  On the images with a lot of clipping it would bring out edges, but detail was clearly not available.

I set the Recovery to 45 on the first image, which brought out some background detail without negatively affecting the overall image too much – this was the result:

Recovery applied to the "just" clipping image

Recovery applied to the “just” clipping image