Shadow & Highlight Adjustment (continued)

Clive R. Haynes FRPS


Shadow / Highlight
The two basic controls of Shadows and Highlights may well be all you need to adjust to improve the tonality of the image but it's well worth exploring a little further and discovering how the other controls can boost your picture. I describe below how the additional adjustments can affect your images. Both 'Shadow' and 'Highlight' sections include 'Tonal Width' and 'Radius' controls.

Tonal Width
This allows the range of tones selected by the Shadow/Highlight 'sliders' to be broadened or lessened. You may wish to improve detail in the very darkest sections without affecting the mid-tones of the image.

This control doesn't specifically address the tonal value but targets the area around the pixels that have been adjusted either spreading or reducing the influence on the surrounding pixels.

Take care when applying the amount of Shadow / Highlight adjustment as 'halos' can appear around sections of the picture. The two controls that have most influence upon the 'halo effect' are 'Amount' and 'Radius'. It pays to take care with the adjustment otherwise the result can appear similar to the 'halos' generated if an image is over-sharpened.

Colour Correction
There's also a control to adjust colour - in essence it can boost or diminish colour saturation. It may be helpful if the result of managing the contrast range results in an unwanted increase in colour saturation.

Midtone Contrast
This allows a further refinement in adjusting tone. It's worth remembering, however, that it only applies to areas affected by the Shadow / Highlight settings.

Black Clip White Clip
Here you can set the 'Clip' values of the highlights and shadows. The 'clipping' will set the range of light and/or dark values that will be applied to the updated black and white values as set the adjustments as they are made
From the two example images at the start of this outline about 'Shadow / Highlight Control' its interesting to compare the individual 'histograms'.
The two 'screen-grabs' below illustrate the way in which the histogram is improved.
Above: This is the 'opening histogram' and one can clearly see the compacting of tones towards the black (left) section of the graph. There is some 'black clipping' exhibited also. The midtones are low in number and the highlights lack 'sparkle'.

Above: After adjustment via 'Shadows / Highlights' we see an improved response. Here the mid-tones are livelier and the whole histogram exhibits an improved contrast range.


Depending upon the image it will probably be good practice in most cases to apply the Shadow / Highlight changes to a copy of the picture (no matter what the image, this advice is generally sound practice thus preserving a version of the 'original'). Situated upon a layer above the original, the 'improved copy' allows a Layer Mask may be applied for selective editing and blending if required.


Know-How Contents
e-mail CRHfoto