Canon PowerShot S120 Manual (en)

Displaying Areas Beyond the Set Range with 
Warning Indicators (Highlight/Shadow 
You can set up warning indicators for both highlighted and shadowed 
parts, which is effective for checking the clipped highlights and shadows 
and preventing excessive adjustment of an image. Where the area on 
the image has exceeded the set range, you can display the highlighted 
part in red and the shadowed part in blue.
Click the [ ] button beside the [
] button, and 
specify settings on the menu that appears.
Checkmark the [Show highlight warnings] and [Show shadow 
warnings] checkboxes and enter the warning values.
You can also select different warning colors from the dialog that 
appears when you click the [Warning color] box.
After specifying settings, click the [Close] button and close the 
Comparing Pre- and Post-Editing Images 
(Single-Image Display)
Select an image and click the [
] button.
On the opened image, if there is an area that exceeds the value 
entered in step 1, the highlighted part of that area is displayed in 
red and the shadowed part is displayed in blue. If you selected 
different warning colors, the parts are displayed in the specified 
Select an image that is being edited and click the 
] button.
By clicking the button, the display switches between the image 
before editing and the current image (being edited).