Image Modes
It's a feature found in all photo editing applications but it rarely gets a mention. Most photographers only ever work in RGB mode—the color mode used by both the camera and the computer monitor. Professionals working in print (with Photoshop CC) will inevitably work in another mode: CMYK (Cyan, Magenta, Yellow, and Black). We don't have this in Elements.
Most photographers will only ever encounter RGB mode, but occasionally you might be sent a file, or download one, that doesn't edit properly, so it pays to check what mode it is set to. Choose Image>Mode>RGB Color to convert it to a full color file, or choose the 8-bit option, if needed (Elements cannot handle higher bit depth files). Other modes under the Image>Mode menu include Grayscale, Indexed Color, and Bitmap.
Grayscale mode: RGB files have three color channels, Grayscale has one: grey. When you convert from RGB to Grayscale, expect the resolution to drop by 60...
