G0Q55A Multimedia: modelleren en programmeren

G0Q55A – Multimedia: modelleren en programmeren 2007/2008

Martin Wolpers & Erik Duval

09 November 2007

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Group presentation groups Some secrets of images Java & Java Media Framework Java Assignment

G0Q55A – Multimedia: modelleren en programmeren 2007/2008 2

Group 5 Jan Sebrechts Sébastien Devynck Pieter Gevers Kim Gressens Iwein Vranckx

Group 6 Jelle Wardenier Laurens Serneels Stijn Adriaensens Tim Boven



Digital images vs. Analog images

Here Digital representations of images

No video! No recording! No capturing!

Presentation based on Fundamentals of Multimedia, Li&Drew, Prentice Hall 2003


Color models (RGB vs. CYM) Gray Images

1-bit Gray scale

Color images (GIF) Color images compression (JPG)


RGB: Red – Green – Blue For monitors: colors add

CMY: Cyan – Magenta – Yellow For printing: colors subtract



C 1 RM = 1 - GY 1 B

R 1 CG = 1 - MB 1 Y


Color ~ (Voltage of color electron gun)gamma

=> not enough light with low voltages


1-bit: white or black 640x480~37,5 kByte

Pixel??



Graphic from www.wikipedia.org


1 pixel = 1 gray value 1 gray value = 1 byte Bitmap = cube with dimension

image size x 8 bit Size 640x480x1Byte

= 300kByte E.g. bmp


Transform 1 pixel to larger pattern Used for 1-bit printers Example

2x2 dither matrix: transform [0..255] -> [0..4] 0:0 1: [1..63], 2:[64..127], 3:[128..191], 4:

[192..255] Better ideas?

Size: 4x640x480x1Byte


24-bit color images 3 channels, 1 Byte per channel 256x256x256 colors (~16M) (more later) Size: 640x480x24bit ~ 900kByte

32-bit color images 24-bit images + special effects channel (1

Byte) 8-bit color images

No direct color information Color look-up index


900kByte300kByte


1byte index into color palette (256 colors) Size: 1bytex640x480 ~ 300kByte


Bitmaps and Container TIFF WMF 8-bit GIF

PNG JPEG

EXIF

Vector formats PS and PDF SVG


TIFF: stands for Tagged Image File Format.

Attachment of additional information (referred to as “tags”) Flexibility

Most important tagformat signifier: type of compression etc. TIFF can store many different types of image

1-bit, grayscale, 8-bit color, 24-bit RGB, etc. TIFF is lossless format but JPEG compression

possible


Microsoft Windows: WMF native vector file format: Consist of a collection of GDI (Graphics Device

Interface) function calls, also native to the Window environment.

“played” a file (typically using the Windows PlayMetaFile() function) == render graphics

Device-independent and unlimited in size.


Graphics Interchange Format GIF87a (original) GIF89a (extension for simple animations)

8-bit color images Interlacing


GIF Signatur

Screen Descriptor

Global Color Map

Image Descriptor

Local Color Map

Raster Area

GIF Terminator

Repeat n times



Length: 2^(Pixel+1)


PNG format: standing for Portable Network Graphics

→ meant to supersede the GIF standard, and extends it in important ways.

Special features of PNG files include: Support for up to 48 bits of color information — a

large increase. contain gamma-correction and alpha-channel

information Progressive display (2-dimensional fashion in

seven passes through each 8 × 8 block)


JPEG Image compression standard (Joint

Photographic Experts Group) 1992 JPEG is a lossy image compression

method transform coding method using the

DCT (Discrete Cosine Transform). An image = F(i, j) in the spatial domain.

2D DCT yields a frequency response which is a function F(u, v) in the spatial frequency domain


Observation 1 Intensity does not change widely in small

areas Observation 2

High spatial frequency less noticed by humans Observation 3

Visual acuity (accuracy in distinguishing closely spaced lines) is much greater for gray (“black and white”) than for color.



Original 20% 5%


EXIF (Exchange Image File) used for digital cameras: Compressed EXIF files use the baseline JPEG

format. Tags (many more than in TIFF) facilitate

higher quality printing, more information about the camera picture-taking conditions (flash, exposure, light

source, white balance, type of scene, etc.) Specification of file format for audio that

accompanies digital images.


Images made up of simple mathematically describable geometrical forms E.g. lines, polygons, circles, bezier curves, etc. Combined and transformed to form complex

objects

File formats PS and PDF SVG: xml based, WWW consortium WMF: windows

Text, too: True Type fonts


Layout and Content are true-copy enabled!

Postscript – language for typesetting Vector-based picture language

Postscript includes text as well as vector/structured graphics.

GL bit-mapped images included in output Encapsulated Postscript (eps) files add additional

information for inclusion no compression (stored as ASCII)

Portable Document format (PDF) LZW compression Without images (compression ratio, 2:1 or 3:1)


Graphic from www.wikipedia.org


Filtershttp://www.ph.tn.tudelft.nl/Courses/FIP/noframes/fip-Morpholo.html

Image processing at TU Delft http://www.ph.tn.tudelft.nl/Courses/FIP/noframes/fip.html

Java Tutorial http://java.sun.com/docs/books/

tutorial/

Java Media Framework http://java.sun.com/products/java-

media/jmf/


Implementation of your CO2 calculator in JavaFollow strictly (!!) Your Storyboard Your Flow Chart /State Diagram Your Layout Your Timeline

Running Applet (!) including source code documentation

Deadline: 21.11.2007


Applet works; name restrictions Programming Syle: readalbe, structured,

layout, naming, ... Document differences to flash, smil, etc.

wnd why! Say who did what for how long Used tools


Documents

G0Q55A Multimedia: modelleren en programmeren