The Levels Adjustment Layer is used for contrast control and color correction, both in the same layer. It’s an extremely versatile tool. If I only had one function available to me in Photoshop, this would be the one. In a well-exposed image, it’s entirely possible that with a few simple adjustments in levels, your image will be ready to print.
I’ve covered this critical subject in two articles. If you haven’t already, I’d strongly suggest that you read Part 1 first, then come back to this article.
White Point /Black Point and Clipping:
Set the White Point and Black Point in your RGB Composite Channel: This gets you on the road to proper contrast. It allows you to set the brightest parts of your image as close to pure white as possible and the darkest parts as close to pure black as possible. By moving the sliders properly, you’ll take advantage of the full range of tonal values available to you in your image; put another way, doing this critical step properly utilizes the full range of dark to light which can be displayed on your monitor and print.
You’ll be using the Clipping Warning quite a bit to get the most out of your image, and this is an important feature. To see a Clipping Warning (the unwanted elimination of pixels), hold down the “Option” key in Mac (“Alt” key in Windows) as you move the “Shadows” and “Highlights” Sliders (there is no clipping warning in the “Midtones” Slider).
When using the Clipping Warning, it should be used as a critically important guide, but a guide nonetheless. What your eyes see is still the best judge of how your image should look. It’s possible that you may sacrifice the “greater good” of the image and live with a bit of clipping (or control it with a Layer Mask, discussed in The Power of Layer Masks in Photoshop) – let your eyes decide.
To Adjust Contrast:
As you can see in the diagram above (and discussed in detail in Part 1 above), you’re able to control the values of Shadows, Midtones, and Highlights. Start by adjusting your white and black points first (no particular order on which one is first), then adjusting your midtone slider.
Note: By the way, I’ve gone “too far” on the Clipping Warning examples shown to the right to show you what it looks like – they aren’t “right”.
~ Move the “Shadows” Slider to the right to increase contrast in the shadow areas. Adjust until clipping just starts to occur. Check this by using your Clipping warning described above. This sets your Black Point.
~ Move the “Highlights” slider to the left to increase contrast in the highlight areas. Be very careful with this one — you don’t want to lose any highlight detail. You can avoid this by not dragging the slider so far to the left that it starts clipping. Adjust until clipping just starts to occur, then back off a bit. Check this by using your Clipping warning described above. This sets your White Point.
~ Move the “Midtones” Slider to the left (or increase the numerical value) to decrease the contrast in the midtones and to the right (or decrease the numerical value) to increase the contrast in the midtones. Too many folks forget to do this, and it makes a world of difference in the “pop” of your image. By moving the slider to the right, you can darken your midtones and brighten your highlights, and vice versa. I call using the “Midtones” slider “Ye Olde Magic Move”. Try it, you’ll like it!
A Color Channel stores information about color elements in the image. You will note that in the Drop-Down menu, you have four choices: RGB, Red, Green, and Blue. Each one of these is a color channel, with RGB being a composite of all three colors. Think of these as being akin to a color filter in front of your camera lens.
To Globally Color-Correct:
1. Click on the Drop-Down Menu, and pick the Color Channel that you desire to add or subtract.
2. Starting with the “Midtones” Sliders, move the appropriate Sliders or input the numerical value to make your desired color correction.
Example: If your print needs more Red, go to the “Red” Channel in the Drop-Down Menu, then move the “Midtones and/or Highlights” Slider to the left to increase the red cast. Conversely, if you desire more Cyan (the opposite of Red), you would move the “Midtones and/or Shadows” slider to the right to increase the Cyan cast.
Here are two “real-life” examples of Levels in action.
Example 1 – Mono Birds:
The original uncorrected image on the left is low in Contrast (flat, a bit dark, lifeless) and has a “magenta-ish” Color Cast (the clouds and the bird are our neutrals). The histogram reflects this: there is very little information in the dark areas and light areas of the graph – just lots of midtones.
The corrected version on the right has more pop to it both in color and contrast, resulting in a pleasing image with a slightly warm color cast to it (check out those neutrals!).
Here’s what was done:
~ Contrast Increase (in the RGB channel):
While using the Clipping Warning, the “Shadows” slider in the RGB Color Channel is moved to the right to increase the “black” (called “D-Max” in the business, and always a good thing in a color print!), the “Midtones” slider is moved to the right to increase punch in the midtones, and the “Highlights” slider is moved to the left to lighten up the overall print. Final values, by the way, of 13/.93/197
~ Global Color Correction (in the Green and Blue channels):
In the “Green” Channel, the “Highlights” Slider is moved to the left to decrease the reddish cast (to 249). Plus, in the “Blue Channel”, the “Shadows” slider is moved to the right (to 5) to add some yellow (the opposite of blue).
Example 2 – McD Family:
The original uncorrected image on the left is a bit high in Contrast and has a “blue-ish / red-ish” Color Cast (the white shirt is our neutral).
The corrected version on the right has more color pop and smoother contrast, opening up the midtones in the faces.
Here’s what was done:
~ Contrast (in the RGB channel):
While using the Clipping Warning, the “Shadows” slider in the RGB Color Channel is moved to the right to increase the “black”, the “Midtones” slider is moved to the left to open up the midtones, in the faces, and the “Highlights” slider is moved to the left to lighten up the overall print. Final values, by the way, of 7/1.28/233
~ Global Color Correction (in the Green and Blue channels): In the “Green” Channel, the “Highlights” Slider is moved to the left to add some green (to 1.03). Plus, in the “Blue Channel”, the “Midtone” slider is moved to the right (to .96) to add some yellow.
Until the next column, have fun and stay well!
Read Part 1: Learn Level Adjustment Layer’s purpose, how to create it, and work with contrast controls and color correction.