Java ThreadsGraphics Programming Graphics Programming: Graphics Devices.
-
date post
15-Jan-2016 -
Category
Documents
-
view
244 -
download
0
Transcript of Java ThreadsGraphics Programming Graphics Programming: Graphics Devices.
Java ThreadsGraphics Programming
Graphics Programming:Graphics Devices
Agenda
Principles of the Cathode Ray Tube (CRT) Vector Graphics Display Devices Raster Display Devices Graphics Device Architectures
Cathode Ray Tube (CRT)
Basic Principle of the CRT
Electrons emitted here
Focused here
x axis deflection plate
y axis deflection plate
Phosphor coatingPhosphor coating emits light from energy provided by electron beam but only lasts for short period and must be ‘refreshed’ to remove flicker of screen image. Typical refresh rates are 60Hz - 80 Hz the higher the more stable is the resultant display.
Cheaper CRTs would not always support higher refresh rates.
Vector Displays Often referred to as Random Scan Devices, stroke-
writing or calligraphic displays Picture definition stored as a set of line drawing
commands Draws each component line in turn Originally designed for architectural and engineering
layouts High resolutions with smooth point-to-point line
drawing functions Not able to display photo-realistic images
Vector Displays
Raster Scan Displays Based on TV Technology Electron beam sweeps scan lines row by row down
the phosphor screen based on information stored in the Frame Buffer ‘painting’ one line at a time
Frame buffer holds total screen area Screen area comprised of picture elements (pixels, or
pel) Often characterised by their resolution, aspect ratio,
and colour depth.
Raster Scan
Display Architecture 1
Display Architecture 2
Raster Scan Properties Resolution = number of pixels avalable on display,
640 x 480 ( VGA ), 800 x 600, 1024 x 768 ( SVGA ) Aspect ratio = number of horizontal pixels / vertical
pixels so 800 / 600 = 1.3. or 4 / 3 = 1024 / 768 etc 4/3 artistically (visually) pleasing? Try wide-screen! Bit depth determined by Frame Buffer - colours
available for each pixel - determined by number of bits stored for each pixel - hence bits per pixel.
1 bit per pixel = monochrome (black and white) Typically 24 or 32 bits per pixel gives ‘true colour’
Aliasing
Aliased
Anti-aliased