UNIT 4

• Reducing the number of bits used to store each pixel leads to two distinctive types of artifacts in images: clipping and quantization artifacts
• Quantization artifacts, or banding, occur when rounding pixel values to the nearest representable value introduces visible jumps in intensity or color
• Clipping occurs when pixels brighter than the maximum value are set to the maximum representable value
• Subtractive color mixing is different from additive mixing
• Pixel formats with typical applications

  • 1-bit grayscale—text and other images where intermediate grays are not desired (high resolution required)
  • 8-bit RGB fixed-range color (24 bits total per pixel)—web and email applications, consumer photographs
  • or 10-bit fixed-range RGB (24–30 bits/pixel)—digital interfaces to computer displays
  • 12- to 14-bit fixed-range RGB (36–42 bits/pixel)—raw camera images for professional photography
  • 16-bit fixed-range RGB (48 bits/pixel)—professional photography and printing; intermediate format for image processing of fixed-range images
  • 16-bit fixed-range grayscale (16 bits/pixel)—radiology and medical imaging
  • 16-bit “half-precision” floating-point RGB—HDR images; intermediate format for real-time rendering
  • 32-bit floating-point RGB—general-purpose intermediate format for software rendering and processing of HDR images
• RGB color space


  Color displayed by mixing three primary lights: red, green, and blue in an additive manner
• Yellow + blue = green in subtractive color mixing
• Most computer graphics images are defined in terms of red-green-blue (RGB) color
• Primary colors are red, yellow, and blue
• Subtractive color mixing is fundamentally different from additive mixing
• RGB color


  A color space that allows straightforward conversion to the controls for most computer screens