View Full Version : Image Contrast and Tonal Range Tweaks Part 2 by Robert Amoruso

Robert Amoruso
10-28-2008, 07:56 PM
Image Contrast and Tonal Range Tweaks Part 2
by Robert Amoruso

Selecting Highlights and Shadows (Photoshop)

Below are three methods for selecting highlights or shadows that can be combined with other tonal control techniques to limit the effect to the selection. One combination of affects, Blending Modes is discussed in the next section.

Method 1: CTRL + ALT + ~

Definition for ~ is the “tilde” key in the upper left of the keyboard. Do not use the shift key on this combination.

Select the highlight areas with CTRL + ALT + ~ (tilde).
Hit CTRL + J to duplicate the selection into a new layer.
Apply your corrections to this new layer.


Select the highlight areas with CTRL + ALT + ~ (tilde).
Select a Curves adjustment from the tool bar at the bottom of the layers palette by clicking on the half moon icon and selecting a curves adjustment. Can also be assessed from the Layer > New Adjustment Layer > Curves menu item.
Use the Curves adjustment to darken overly bright highlights or brighten dark shadows.

By selecting the highlights and creating a curves adjustment layer, the resulting mask is a tonal gray scale with the brighter highlights closer to white in the mask. The highlight mask below looks like a B&W image.



To select the shadows, after executing step one above, hit Shift + CTRL + I to inverse the selection.

By selection the highlights, inversing them to select the shadows and creating a curves adjustment layer, the resulting mask is a tonal gray scale with the darker shadows closer to white in the mask. The shadow mask below looks like a B&W negative.


Method 2: Channels Palette


Using the Channels Palette above, a highlight weighted tonal mask can be created by holding down the CTRL key and clicking on the RGB image. Note the CTRL + ~ at the right. This selection is the same as the one created in Method 1 using the CTRL + ALT + ~ key combination. However, using the Channels Palette gives you the added ability to create highlight selections using the Red, Green or Blue Channels only. For comparison, the following shows all four gray scale masks.


Method 3: Color Range

Color Range is accessed in the menu under Select > Color Range. You can use it to select a brightly-colored--highlights to make a selection of highlights and adjust fuzziness to increase or decrease the selection. Selection Preview shows white areas as selected pixels, black areas unselected and gray areas partially selected as well as the Quick Mask selection that can be fine-tuned further.


From the PSCS3 Help

Choose Select > Color Range.
Choose the Sampled Colors tool from the Select menu. You can also choose a color or tonal range from the Select menu, but you won’t be able to adjust the selection. The Out‑Of‑Gamut option works only on RGB and Lab images. (An out‑of‑gamut color is an RGB or Lab color that cannot be printed using process color printing.)
Select one of the display options:

Selection Previews the selection that will result from the colors you sample in the image. White areas are selected pixels, black areas unselected, and gray areas partially selected.
Image Previews the entire image. For example, you might want to sample from a part of the image that isn’t on‑screen.
To toggle between the Image and Selection previews in the Color Range dialog box, press Ctrl (Windows) or Command (Mac OS).

Position the eyedropper pointer over the image or preview area, and click to sample the colors you want included.
Adjust the range of colors selected using the Fuzziness slider or by entering a value. The Fuzziness setting controls how wide a range of colors is in the selection, and increases or decreases the amount of partially selected pixels (gray areas in the selection preview). Set a low Fuzziness value to restrict the color range, a higher value to increase the range.
Increasing fuzziness expands selection.
7Adjust the selection:

To add colors, select the plus eyedropper, and click in the preview area or image.
To remove colors, select the minus eyedropper, and click in the preview area or image.

To activate the plus eyedropper temporarily, hold down Shift. Hold down Alt (Windows) or Option (Mac OS) to activate the minus eyedropper.
To preview the selection in the image window, choose an option for Selection Preview.
To revert to the original selection, hold down Alt (Windows) or Option (Mac OS), and click Reset.
To save and load color range settings, use the Save and Load buttons in the Color Range dialog box to save and reuse the current settings.

Gradient Masks (Photoshop)

A gradient mask can be used as the digital equivalent of a Graduated Neutral Density (GND) Filter.

The GND filter is a neutral density filter (from Ref. 1) with a clear to neutral gray gradient transition. Most filters sold today are half clear and half neutral density with hard or soft (feathered) transitions. Common usage is to reduce the contrast of a bright area in an image (like the sky) into the dynamic range of the recording medium. The classic example being a bright sky and darker foreground like a meadow. Expose for the sky and the meadow is too dark – expose for the meadow and the sky is washed out. A GND Filter helps to bring the contrast extremes closer together.

Caveat: This is not a replacement for using a GND filter in the field. If you overexpose the sky getting the FG tonality correct, this technique will not bring that sky back. However, you will find it a useful technique in many instances.

Reference 1: Neutral density filter. (2008, August 9). In Wikipedia, the Free Encyclopedia. Retrieved 22:12, September 7, 2008, from http://en.wikipedia.org/w/index.php?title=Neutral_density_filter&oldid=230731861.

1. Select the Gradient Tool. It is found in the tool bar and looks like a graduated neutral density filter.

2. Using the Gradient Tool.

You created a Curves adjustment to lower the sky's brightness and restore detail.
You used a blending mode to adjust the tonal relationships of a overly-bright sky.
But you need to limite that correction to the sky. You could paint areas out you don’t want affected or use the opacity slider to minimize the blending mode affect.
Or use the gradient tool whose properties are accessed in the options bar (below menu bar at top of screen) to select the gradient type and to modify it.

Options in the options Bar from left to right are the following.

1. Drop-down box for tool presets. You can save preset gradient masks here.

2. Edit Gradient Mask.

Select either mask “A” or “B”. (Illustration below)
Mask “A” is synonymous with setting the foreground color to white when the gradient tool is selected.
Mask “B” is synonymous with setting the foreground color to black when the gradient tool is selected.
When Mask “A” is used, a white to black transition occurs.
When Mask “B” is used, a black to white transition occurs.

3. Select an option for applying the gradient fill in the options bar

Select a Linear Gradient (illustration below) which shades from the starting point to the ending point in a straight line.

4. Blending Modes and Opacity can be set in the Options Bar.

I don’t use these much but they can be useful.

5. Use Reverse to toggle from “A” to “B” mask. Dither and Transparency have additional uses. I suggest you use the PSCS help system and search on “Specify the gradient transparency” for further information.

The Gradient Editor can be used to change the transparency of the gradient.
Access it by double clicking on Edit Gradient Mask in the Options Bar.


In the image below, I drew the gradient line from the top of the image to the bottom. This paints white to black when the “A” mask preset is used.


By holding down the ALT key and clicking on the curves adjustment mask, the gradient mask is revealed below.


By drawing a much shorter line starting above the horizon to just below it, a sharper transition can be created as show below.


Dave Phillips
11-27-2008, 11:12 AM
awesome info/technique for a learner like me....much appreciate the effort this took

Jason Searle
02-11-2009, 03:14 PM
Thanks Robert for the time and effort to put this together :)

Jack Faller
02-25-2009, 10:54 AM
Thanks for developing this tutorial. Those with CS4 might note that Adobe has changed the keyboard shortcut defaults so that loading the RGB channel as a selection is now ctrl+alt+2. One tip I might offer is that one reason for selecting highlights is to remove a reflection or enhance contrast in the whites using linear burn.


select/color range/highlight produces a selection with less midtones & shadows than ctrl+alt+~, but may still produce burnt edges when used with linear burn or multiply blend modes. This effect can be modified further by limiting the fraction of highlights used and "feathering" the effect using the BLEND IF options. Splitting the black pointer (ALT drag) produces a gradient of the effect so that the edges blend in better.

Juan Carlos Vindas
04-16-2009, 07:31 PM
Thanks a lot Robert for this huge lesson of Photoshop!
I will practice is soon and hope to be able to upload an image here to show the results. Thank you once again. jc