Color wheels have been around forever. The ones from stores are subtractive. They are used for mixing paints and inks for printing on paper in CMYK (Cyan, Magenta, Yellow, Key [black.]) . An RGB (Red, Green, Blue) color wheel shows how digital cameras and Photoshop (Lightroom too) create the spectrum of hues in digital photography. Adobe Color CC (Window > Extensions > Adobe Color Themes… in Photoshop,) shown above, in an interactive color wheel. The compliments of photographic light are cyan, magenta and yellow. Follow the steps below to make your own RGB color wheel to experience how RGB color works.
Make a new document in Photoshop
Choose File > New… in Photoshop’s main menu or use Command (WIN: Control) + N. Click Photo in the New Document window. Set the height and width to 8 inches with 300 as the resolution. Choose 8-bit. Set the Color Profile to sRGB. Click Create.
Create a new blank layer then make a circular selection
Choose Layer > New… from the main menu or press Command (WIN: Control) + Shift + N. Name the layer Blue. Get the Elliptical Marquee tool. Hold down the Shift and Option (WIN: Alt) keys then click in the center of the document. Drag out a circle. The Shift key makes the circle. The Option (WIN: Alt) key makes the tool center on the cursor. Size it to about 1000px by 1000px. The size is not critical.
TIP: While the selection is being drawn, a heads up readout showing the height, width, X & Y positions appears.
Fill the layer with blue
The Blue layer is active. Click on the Foreground color. The Color Picker dialog opens. Click on the Blue: entry window radio button. Enter 255. 255 is the brightest a color can be in Photoshop. Click OK. The blue appears as the Foreground Color in the toolbar. Pick Edit > Fill… from the menu. Select Foreground Color. Click OK. The keyboard shortcuts are Option + Delete for MacOS and Alt + Backspace in Windows.
Duplicate Blue then make it Green
Blue is still active (highlighted.) Choose Layer > New > New Layer via Copy from the menu. The shortcut is Command (WIN: Control) + J. Rename the layer Green. Click on the blue foreground to open the Color Picker. Tick the Green radio button. Put 255 in the entry window. Press tab to make Blue active. Enter 0 (zero.) Click OK. In the Layers panel, click the Lock Transparent Pixels checkbox (Shown in Red in the Layers Panel screenshot.) This allows changing the blue pixels to green without making a new selection. Use either Fill from the Edit menu or the shortcut above to fill the blue pixels with green.
Duplicate Green and turn it Red
Green is now active. Duplicate the layer. Name it Red. Choose Red in the Color Picker. Click the Lock Transparent Pixels button. Fill the green pixels with red.
Secret sauce–the Screen Blending Mode
Highlight the Background layer. Go to Image > Adjustments > Invert. The layer turns black. Highlight the Blue layer. Click on the menu disclosure arrow to the right of the word Normal. Change it from Normal to Screen. Next choose Green. Make its Blending Mode Screen. Do the same for the Red Layer. As soon as this happens, all three circles become white. The black Background layer is the key to making the Screen mode work.
What is white?
White in Photoshop happens when all three primary colors, Red, Green & Blue are at 255 each one at its brightest. With all three colors aligned in the Screen Blending Mode, the result is white. Now let’s make color.
Realizing the Photographic Color Wheel
Choose the Move tool. Red is active. Click in the center of the white circle. Drag the Red layer up and to the left. Cyan, the compliment of Red appears where the Red no longer overlaps the other two. Next, highlight the Green layer. Drag it up and to the right. Where Red and Green overlap Yellow appears. Directly below it is its compliment Blue. Red and Blue together create Magenta, the compliment of Green. Where all three overlap White remains. Just for fun, highlight the Green layer. Change its Opacity to 50%. What color does 100% Red and 50% Green make? Interesting isn’t it? By changing the opacity of these layers in 1% steps, over 16 million colors can be created in Photoshop.
Make the final RGB Color Wheel
Color wheels are typically against white. If the Background layer is changed to white, the Screen Blending Mode will turn everything white. What to do? First, hide the Background layer by clicking its eye icon off. Now, highlight the Red layer. Hold down the Option (WIN: Alt) key, then choose Merge Visible from the Layers panel. A new layer appears at the top of the layer stack with all of the layers below it that are visible on it. Finally, show the Background layer and invert it back to white. The shortcut is Command (WIN: Control) + I. Save the file. There will be occasion to use it again in a future post.