I don't recall any other bloggers posting here about the incredible usefulness of the option key in conjunction with several sliders in the Develop Module of Lightroom. This is a well known "trick" of the trade and a huge reason why Adobe Camera Raw and Lightroom have such a large following. The gist of this post is that by holding down the option key (on Mac, ALT key on PC) one can see exactly where the highlights or shadow detail is clipped and then of course you can adjust it as you wish. Basically this is a really quick and easy way to set your white and black points with amazing accuracy.

As an example of this powerful technique, let's take the image at right that I recently shot in Torres del Paine National Park in southern Chile. It is a rather dark image because it was shot at 4 AM with a very long exposure, hence the blurred clouds. With this type of image you'd suspect that there are some shadows that are clipped (meaning they are completely black with no detail) and maybe even the headlamp the climber is wearing is clipped on the highlight end of the histogram as well.

If I hold down the option key while I click on the Blacks slider in Lightroom's Develop module I will see something like the image at right (below this paragraph). Everything in this image that is not white is an area where one or more channels is clipping and any part that is black is where the image is completely black - i.e. the histogram information for these parts of the image are 0,0,0 for Red, Green and Blue. I can adjust the Blacks slider in Lightroom while holding down the option key to either make more of my image completely black or by moving the slider to the left opening up more detail in the shadows.

For my taste, having come from film, I don't mind some parts of my image going completely to black, but I might open the Blacks up just a little bit here (say to 3 or 4) so the image will print well.

On the other side of the histogram, dealing with the highlights I can use the same trick. Because this image doesn't have many highlights blown out as an example I am going to take the exposure slider and crank it all the way over to + 3.45 and then hold down the option key so you can get a sense of what blown out highlights look like. As in the upper image at right, the sky is blown out in the blue channel and the headlamp is blown out in all channels because it shows up as white.

But of course this is because I have cranked the exposure way up - in reality the image only has clipped highlights in the headlamp light as in the lower image at right.

The headlamp light is so bright that it will not be able to be recovered even with the recovery slider all the way to the right. But as it should be - since it is so bright - I don't mind that this part of the image is clipped.

As you might have guessed by now Lightroom not only shows you what part of the image is clipping on either the highlight or black end of the histogram but it also shows you which channels (or mixture of channels) are clipping as well by the colors you see when you hold down the option key. If you are clipping the red highlights then you'll see red when you hold down the option key plus the Recovery (or Exposure) slider.

When I am working up an image this is the first thing I do to set the white and black points of every image. Then I can adjust the brightness and White Balance and get on with the rest of the image processing.

That's it for this session. See you next week.

Adios, Michael Clark