Week 4: Color
Basic Digital Photography with Matthew Swarts
For Next Week:
Read about Joseph Albers.
Read about Color Theory.
Download and review the slides from this week’s lecture: arts1850 week 4 color slides
Making Friends with the Histogram
And in the Curves Properties Window:
Adjusting the White Balance of Your Images using Camera Raw
Most of the time, keeping your camera on AWB (Auto White Balance) produces fairly acceptable results in terms of the overall color temperature of your image. Luckily, if your file has an unsightly color cast (either too cool or too warm), you can quickly adjust this inside Camera Raw. The interface slider for White Balance is located in the upper right hand corner of the interface.
When you open your image, the White Balance should display “As Shot”. As you adjust the sliders, the setting will shift to “Custom.” Use the white balance slider to delicately adjust the coolness or warmness of the image. What you really want to look for is a way to have the color balance be relatively neutral in the shadow details, with slightly warm highlights (if you are trying to represent normal daylight.) If you have photographed indoors and used artificial lighting, the White Balance temperature slider offers you ample opportunity to color correct the cast of the lighting. Most of the time this means you will shift the slider slightly toward a cooling influence, to take out the yellow cast of tungsten lighting.
Using A Levels Adjustment Layer to Correct Color
With an image open in Photoshop, click on the Levels adjustment icon in the Adjustments panel. The Levels Properties window will open and should look similar to this:
In the Levels Properties window, observe the characteristics of the histogram, noting if there is any ‘extra space’ to either the left or right hand sides of the graph. If you have space on either side, your image will likely benefit from a Levels adjustment. The procedure is as follows. Hold down the ‘option’ key while you select and minipulate either the leftmost or rightmost slider of the Levels properties. Holding down the ‘option’ key activates what is known as Threshold mode. This allows you to see the darkest and lightest areas of your image quickly, and adjust the sliders so that you avoid clipping important image information. With the ‘option’ key held down, the sliders operate to simplify the image information into a threshold map. This pixelated version of your image will change as you slide the sliders back and forth. Get in the habit of holding down the ‘option’ key and sliding the dark and light sliders appropriately, noting just where information begins to appear at either extreme. When you know where these points occur on the graph, you can ‘back off’ a little on the sliders and adjust the levels accordingly.
In the example above, you can see I have slid the leftmost Levels slider in the Properties window slightly toward the right, stopping just before the information in the graph begins to appear visible. Moving the slider like this remaps the tonal values of the image (in this case extending them a little) and changes the way the image looks on the monitor. Get in the habit of carefully studying the link between the changes on your monitor and your mouse and keyboard commands! The right hand slider is also placed all the way to the right, allowing the highlights to have their full range, as a small amount of information appears visible throughout the right hand side of the graph. The central slider is known as the gamma control, and allows you to adjust the brightness of middle values in the your image. Adjust this last, but not least.
Most images will benefit from very slight and careful Levels adjustments. It’s good practice to set up a Levels adjustment layer immediately when opening an image, along with a Curves adjustment layer, which we’ll talk about next.
Using Curves To Adjust Color
With an image open in Photoshop, click on the Curves icon in the Adjustments panel to bring up the Curves Properties window. Your interface should look similar to this:
Believe it or not, most of the tools you might use in Levels are replicated in Curves. Note the display of the histogram and the familiar shadow and highlight sliders alongside the bottom section of the graph. You can hold down the option key to enter threshold mode and slide both sliders to see where your black and white points begin. Make this adjustment first, being extremely careful to ‘back off’ once you’ve found the appropriate position for each slider. In the example image above, I had the opportunity to slide the highlight slider very slightly to the left, increasing the brightness of the image and clarifying the whites. The resulting change in the Curves window looked similar to the following:
After making this basic adjustment to your image inside the Curves Properties window, your next step is to establish your white point. There’s a handy eyedropper tool that is selectable in the Curves Properties window. There are actually three eyedroppers, one for the black point, one for the middle grey, and one for the white point. In the image below, the white point eyedropper is selected:
As it sounds, the white point eyedropper allows you to set any point in your image to white, remapping the values for every other area of the image accordingly. Use this tool with precision and caution! It will make very subtle and beautiful changes to your image when used correctly. When used improperly, it will cause your image to break down and colors will be misrepresented. The trick is to locate the whitest point in your image using threshold mode (hold down the option key and slide the histogram levels sliders accordingly). Once you know precisely where your whitest point is, simply zoom in on that area in your image to isolate it accordingly, and then, with the white point eyedropper selected, click inside this area in your image. The colors of your image will be remapped accordingly, and the remapping will show up in the Curves Properties window:
The resulting change in the image is subtle, but important:
Using a Saturation Adjustment Layer to Adjust Individual Colors
With an image open, click on the Saturation icon in the Adjustments panel. The interface will look similar to this:
This is a great interface for adjusting the overall saturation, hue, and lightness of your image. It is possible, however, to refine individual colors in your image by selecting the hand icon that looks like this:
When this tool is selected you have the ability to control the saturation of individual color groups with the mouse. Click anywhere you want to alter the saturation of a particular color in your image. The mouse will change and you can either slide left to desaturate or slide right to saturate. Observe how when you select a color with the mouse, Photoshop selects the appropriate color group from the pulldown menue in the Properties window. As you manipulate the mouse, the slider moves accordingly in the window. Do this for key colors in your image, varying their saturation to see what’s possible. Again, this tool is very precise and powerful, and it’s often by experimentation across the range of colors in your image that you come upon the best results.
Adjusting the Vibrance with a Vibrance Adjustment Layer
With an image open, click on the Vibrance icon in the Adjustments panel. This slider allows you subtly (or grossly) affect the relationship between colors in your image. Sliding it further to the right makes some images ‘pop’ a little better, increasing the saturation of lesser colors and protecting the already saturated ones. Often photographers will apply a vibrance adjustment last, after Levels and Curves and Saturation, to provide one final boost to the image’s appearance. Experiment, especially this week, with how you can improve your image with this tool.