Ph'D' course in Image Analysis and Digital Microscopy

1
Ph.D. course inImage AnalysisandDigital
Microscopy
University of Copenhagen Biological
Institute Department of Evolutionary Biology
2
(No Transcript)
3
What is a digital image?
4
A digital image

• It is a matrix

5
A digital image

• It is a matrix
• Each cell or picture element is called a pixel

6
A digital image

• It is a matrix
• Each cell or picture element is called a pixel
• Each pixel contain a value representing a colour
  or a shade of grey

7
An example7 x 7 pix 1 bit
8
An example7 x 7 pix 1 bit
9
A digital image

• It is a matrix
• Each cell or picture element is called a pixel
• Each pixel contain a value representing a colour
  or a shade of grey.
• The number of different values one pixel can
  contain is called the image depth (bits per pixel
  - BPP).

10
Bit depth (BPP)

• In the computer figures are represented by bits.

11
Bit depth (BPP)

• In the computer figures are represented by bits
• Each bit can have one of two values - 0 or 1

12
Bit depth (BPP)

• In the computer figures are represented by bits
• Each bit can have one of two values - 0 or 1
• Bits are arranged in groups of 8 called a byte

13
Bit depth (BPP)

• In the computer figures are represented by bits.
• Each bit can have one of two values - 0 or 1
• Bits are arranged in groups of 8 called a byte
• One byte (8 bits) contain 256 different
  combinations (28) of 0 and 1. Ex 10010000 or
  111101011

14
Bit depth (BPP)

• 1 BPP - 2 colours or greys (21)
• 2 BPP - 4 - (22)
• 4 BPP - 16 -
  (24)
• 8 BPP - 256 - (28)
  
• 12 BBP - 4096 - (212)
• 24 BPP - 16 mill. colours (224)

15
Bit depth (BPP)
1 BPP
4 BPP
8 BPP
12 BPP
4.3 Kb
16.2 Kb
32.9 Kb
65.8 Kb
All images are grey scale images
16

Colour images
8 bits, 256 colours
The palette used
17

Colour images
18

Colour images
The palette used for the right image
19
Colour images
RGB colours and CMY colours
R
G
Y
M
C
B
Background colour R160 G190 B160
20
Colour images
3 x 8 bits, 16 mill. colours

Red channel 8 bits 256 shades
Green channel 8 bits 256 shades
Blue channel 8 bits 256 shades
21
Colour images
3 x 8 bits
R G
B
22
Colour images

• Colour based encoding schemes
  RGB, CMY or CMYK
  Analogue separation possible
• Non-colour based encoding schemes
  HSI (Hue, Saturation, Intensity), HSL or HSV.
  
  Analogue separation impossible.

Background colour R160 G190 B160 H85
S48 I175
23
Types of images
Anything that can be represented by a matrix
24
Types of images
Normal photographs
25
Types of images
SEM photographs
26
Types of images
Astronomical
27
Types of images
Electron microscopical
28
Types of images
NMR and CT scans
29
Types of images
Gel images
30
Types of images
By having colors representing the
different hights, a topographic map can easily be
analysed
31
Types of images
Sound
32
(No Transcript)