Positioning the cursor over the triangles in the upper left and right of the Histogram panel will display areas of the photograph that are clipping to pure black or pure white. Areas that are clipping to black are shown with a blue overlay, areas clipping to white are shown with a red overlay.
Moving the cursor away from the shadow/highlight clipping icon hides the overlay. For a more constant display of the overlay, click the warning icon to show, click again to hide – or tap the “J” key to toggle on/off both of the shadow/highlight clipping previews at once.
An alternate way to preview clipping is to Opt (Mac) /Alt (Win) -drag the Exposure, Highlights, Shadows, Whites and/or Blacks sliders in the Basic panel. This differs from the clipping warnings above as you will see a per channel clipping preview displayed.
Note: In order to preview the clipping warning in ACR in Photoshop, tap the “O” / “U” key. Similar to Lightroom, clipped highlights will be displayed in red, shadows in blue. I remember these shortcuts by thinking of Over/Under exposure.
Hovering your curser over the triangles in the upper left and right of the Histogram panel in Lightroom’s Develop module displays a red or blue preview of the clipped values in the image preview. To toggle on this clipping preview (so that it remains displayed as you move your cursor to other areas), tap the “J” key. The red overlay shows where information in one or more channels (R, G or B) of the image is pure white. The blue overlay shows where information in one or more of the channels (R, G or B) of the image is pure black.
To preview (more specifically) which channel is being pushed to pure black and white, Option (Mac) / Alt (Win) + drag the Blacks/Exposure sliders. Where the image preview is pure black or white, all of the channels are clipped, the various colors show which individual channels (or combination of channels) are clipped.
In this episode, I will demonstrate how to streamline Lightroom 3’s Develop module by taking advantage of my top 10 favorite shortcuts & time-saving features in order to eliminate many of the repetitive image adjustment tasks when editing large volumes of images.