sierra panorama

Tweaking Your Photos, Part 1:

Using the Luminance Slider in Camera Raw or Lightroom

This is the first part in a series of tutorials on Tweaking Your Photographs. These tutorials will generally be regarding subtle tweaks to images in ways that the average digital photographer may not know about.

The Luminance tool in Camera Raw or Lightroom is one that is overlooked by many who use these programs. However, I've found that the Luminance tool can be very useful in certain situations:

1. To make certain colors "pop", such as backlit fall leaves. It can sometimes be difficult to get the digital photo have the same "pop" as the original scene did. By lightening the appropriate color with the Luminance sliders, one can create a digital photo more representative of the original scene.

2. Sometimes details of bright red colors can be lost, even though there has been no clipping of the reds in the histogram. By lowering the luminance of the reds, detail can be brought back.

The Luminance sliders are located in the Develop Module of Lightroom, in the HSL tool group. In Camera Raw it is found in the HSL tab.

The photo below shows canoeists on Moraine Lake in Canada. The canoeists are framed by evergreen trees, which don't show their color well. Sliding the Shadows slider to the far right helped a bit, as shown in the original image below. The rollover image (roll your mouse over the photo) shows how much the trees are improved by using the green luminance slider set to the far right, or 100 units:

Effect of Luminace Slider

For those of you using mobile browsers, which cannot use rollover images, the image below shows the result of using the green luminance slider:

After luminance slider

The San Diego Zoo has some marvelous walkin aviaries containing many brightly colored, tropical birds. Sometimes the bright colors, particularly the reds, are simply too strong for the camera's sensor. The photo below of a Collared Lory is one example. There is no apparent clipping of red in this photo as judged by both the histogram and by alt-clicking on the Exposure slider in Camera Raw. However, the red breast is lacking in feather detail in some areas.This can be helped by reducing the exposure, but the green back becomes duller than it is in real life. A better option is to use the red luminance slider to reduce the red luminance slightly. This brings out more of the red breast detail, as can be seen by rolling your mouse over the image or looking at the second photo (for mobile device users).

Lory-luminance reduction

Here is the version with reduced red luminance for mobile device users:

Lory reduce luminance


How to make local luminance changes:

Sometimes you may want to change the luminance of one or a few areas in a photograph. This can be easily done with the latest Photoshop CC 14 (introduced in June 2013), provided you can use one of Photoshop's selection tools to choose the desired area. This version of Photoshop allows you to use Camera Raw as a filter. Therefore, all you have to do is to make your selection, then go to Filter/Camera Raw in Photoshop's top menu. Only the selected areas will be shown in Camera Raw. Then you can just go to the HSL tab in Camera Raw as usual and change the luminance as described above. In this way only the area selected in Photoshop will have the luminance change.

In the photograph below the osprey's eyes do not show well. Their eyes are recessed so the light doesn't always illuminate them efficiently. By increasing the luminance of the eyes only, you can increase the impact of the photograph and show the eyes as they can really appear, without altering other aspects of the image. This is a subtle change that can make a good photograph better.

The photo below shows the original image, and the rollover image has yellow luminance added to the eyes.

Osprey Eyes

For mobile device users, here is the rollover image:

Osprey plus lum

So what do you do when you want to change the luminance of an area that you cannot select, or you do not have Photoshop CC 14? This becomes more complicated, requiring a good understanding of layers and masks. In these situations you will have to make a mask and paint the area white where you want the luminance change. Here is the protocol:

1. Open the original image in Camera Raw (any version) without any luminance adjustments.

2. Open the image in Photoshop.

3. Open the same image again in Camera Raw, but this time adjust the desired luminance slider all the way to the right, if adding luminance, or left, if reducing luminance. Don't worry if this results in more of an effect than you intended. You will be able to control the exact amount needed in the steps below.

4. Open this adjusted image in Photoshop also. Now you should have two open images, one with no luminance adjusted, the other with a maximum amount of luminance adjustment.

5. The two images need to be floating in the window, not in a fixed position. The later versions of Photoshop open files in tabs, which are docked to the menu bar at the top. To make them floating, or movable in the window, go the top menu and select Window/Arrange/Float All In Window.

6. Drag the images in the window so they are not directly on top of each other. Some overlapping is OK.

7. Click the Move tool, which is the topmost tool in the toolbar, or press the v key.

8. Holding the shift key down, drag the image with adjusted luminance on top of the image with no luminance adjustment. This will create a file with two layers exactly superimposed on each other. Check this by opening the Layers palette. If it isn't visible, you can open it by going to the top menu and selecting Windows/Layers. The top layer will be the adjusted layer, while the bottom layer will unadjusted.

9. In the Layers palette, make sure the topmost layer is selected by clicking on it.

10. On the top menu, select Layer/Layer Mask/Hide Selection. At this time the image will appear to be unadjusted. Previous to this step, the image appeared to be maximally adjusted, since it is the top layer. However, after converting the top layer to a mask with everything hidden, only the bottom (unadjusted) layer will show.

11. We now want to paint on the mask with white to allow the desired adjusted area to become visible. The more white that is painted in, the stronger the effect will be.

12. Press the B key to select the Brush Tool (or click on the Brush Tool in the Toolbar), and then press the D key to set the foreground color to white, and the background color to black.

13. Press the shift key and the press the left bracket key 4 times to make the brush as soft as possible. Then adjust the brush size by clicking the left bracket to make it smaller, and the right bracket to make it larger.

14. In the tool properties area just above the photo, select Mode = Normal, Opacity = 100%, and the Flow about 5%. If the Flow is set too high, you will not be able to control the amount of change accurately.

15. In the Layers Palette, click on the black mask rectangle in the second layer.

16. Use the brush to paint white over the area of the photograph where you want to change the luminance. Paint more holding down the left mouse button to increase the effect. If you go too far, press the X key to make black the foreground color. Now you can reverse the effect as much as needed.