Photoshop CS3

digital basics

*VSVY HUK SPNO[ V]LY]PL^ Additive color The additive primary colors of light are Red, Green and Blue or RGB. Mixing any two of these primary colors creates one of the three secondary colors Magenta, Cyan or Yellow. Note > Mixing all three primary colors of light in equal proportions creates white light. :\I[YHJ[P]L JVSVY The three subtractive secondary colors are Cyan, Magenta and Yellow or CMY. Mixing any two of these secondary colors creates one of the three primary colors Red, Green or Blue. Mixing all three secondary colors in equal proportions in a CMYK file creates black or an absence of light. (J[P]P[` ¶ *OHUULSZ HUK 0UMV Open the files ‘RGB’ and ‘CMY’ from the supporting 1. DVD. When opening these files choose ‘Leave as is (don’t color manage)’ in the Missing Profile dialog box. Open the Channels palette to see how these six colors 2. plus white and black were created using information from three (RGB) or four (CMYK) channels. Use the Eyedropper Tool and the Info palette (Window > Info) to measure the color values. /\L :H[\YH[PVU HUK )YPNO[ULZZ Although most of the digital images are captured in RGB it is sometimes a difficult or awkward color model for some aspects of color editing. Photoshop allows the color information of a digital image to be edited using the HSB model. Hue, Saturation and Brightness or HSB is an alternative model for image editing which allows the user to edit either the Hue, Saturation or Brightness independently of the other two. (J[P]P[` ¶ *VSVY 7PJRLY Open the HSB image from the supporting DVD. 1. Click on the foreground color swatch in the Tools 2. palette to open the Color Picker. Move the cursor into the image window and click on 3. each color in turn to review the HSB color values.

RGB – additive color

CMY – subtractive color

HSB – Hue, Saturation and Brightness

21