Lecture Notes

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• Analysis by overlay
• Guidelines
• RGB v CMYK color

• Bit depth

• Photoshop is an example of CPU intensive computing.
• This is because every manipulation requires the processor to analyze each pixel.
• The modes option under the layer menu allows the user to select which display mode is to be used. (Bitmap, grayscale, duotone indexed color, RGB, CMYK, lab, and multi-channel).
• Bitmap-one bit = one pixel (Great for live drawings).
• Bit depth-number of bits assigned to a pixel.
• Grayscale-eight bits per pixel =2⁸=256; therefore 256 shades of grey can be displayed.
• 0=white……255=black
• RGB-color of electronic display (projection).
• CMYK-color used to produce printed images.
• 8 bits / channel versus 16 bits / channel
• 8 bits / channel = 24 bits total = 2²⁴ = 16+ million colors
• 16 bits / channel = 48 bits total = 2⁴⁸
• Layers can be used to keep track of various objects, allowing the user to turn each on and off, as well as edit them independently of each other.
• The first layer one will see is titled background, which cannot be edited unless one double clicks on its name, and then assigns it another title.