Photoshop

1
Photoshop

• Basic Theory

2
Bitmap vs Vector

• Bitmap based on pixels
• Pixel is the smallest element of a bitmap
• Used in Photoshop
• Change in size changes quality
• Vector based on mathematical formula
• Used in Illustrator
• Change in size does not affect quality

3
Bitmap

• Measured in pixels
• Bit-depth is the amount of digital storage space
  used to record information about the color of a
  pixel
• 24 bit scan with 256 gray levels
• 24 bit monitor with 16 million colors

4
Pixel

• Short for picture element
• Smallest element of a bitmap
• In Photoshop you edit pixel information
• Change color
• Change shade
• Change brightness

5
Resolution

• Measured in pixels per inch (ppi)
• Pixel size varies based on resolution
• 100 ppi 1 pixel 1/100 of an inch square
• 300 ppi 1 pixel 1/300 of an inch square
• Dragging a corner and changing size does not
  change the number of pixels
• Printer resolution is not the same as image
  resolution

6
Color Models

• RGB Red Green Blue
• Mirrors the way a human eye sees color
• Used in scanners, digital cameras, and monitors
• RGB are the additive primaries
• 100 of Red Green Blue light White

7
Color Models

• CYMK Cyan Yellow Magenta Black
• Used in Printing
• CYM are secondary colors
• Also called the subtractive model
• Take away all 3 when printing white
• All 3 together should make black but makes a
  muddy brown because of impurities
• Printers add Black to make a true black

8
Color Gamut

• The range of colors that a specific device is
  capable of producing
• Makes the printing process complicated
• Gamut of a monitor does not equal the gamut of a
  printer.
• Some colors cant be matched
• Vibrant yellows or deep blues

9
Which Mode to Use

• Use RGB mode if image is intended for WWW.
• Use CYMK or RGB if image is intended for print
  but make sure you convert to CYMK before going to
  another program to set up printing (Illlustrator)

10
Color management

• Several settings available in Photoshop
• Edit Menu gtgtColor Settings
• Use Web Graphics Defaults for WWW
• Use US Prepress Defaults for print
• Can create custom but not recommended for
  amateurs!

11
Monitor Calibration