slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Digital Imaging and Image Analysis Bozzola and Russell – Chapter 18 PowerPoint Presentation
Download Presentation
Digital Imaging and Image Analysis Bozzola and Russell – Chapter 18

Loading in 2 Seconds...

play fullscreen
1 / 46

Digital Imaging and Image Analysis Bozzola and Russell – Chapter 18 - PowerPoint PPT Presentation


  • 260 Views
  • Uploaded on

Digital Imaging and Image Analysis Bozzola and Russell – Chapter 18 http://www.uga.edu/caur/maflect.htm Lascaux Cave in Southern France 15,000 years B.C.E. For thousands of years mankind has been trying to convey to others his observations of nature through the use of images.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Digital Imaging and Image Analysis Bozzola and Russell – Chapter 18' - niveditha


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Digital Imaging and Image Analysis

Bozzola and Russell – Chapter 18

http://www.uga.edu/caur/maflect.htm

slide2

Lascaux Cave in Southern France

15,000 years B.C.E.

For thousands of years mankind has been trying to convey to others his observations of nature through the use of images.

slide4

Robert Hooke

1635-1703

Antoni van Leeuwenhoek

1672-1723

slide5

Robert Hooke

1635-1703

Antoni van Leeuwenhoek

1672-1723

Ernst Haeckel

1834-1919

slide6

Louis Jacques Mande Daguerre

1787-1851

Photography or “light writing”

is the process by which an image is recorded without the aid of drawing.

slide7

Louis Jacques Mande Daguerre

1787-1851

Daguerre’s method consisted of treating silver-plated copper sheets with iodine to make them sensitive to light, then exposing them in a camera and "developing" the images with warm mercury vapor. Such images came to be known as Daguerreotypes

Joseph Nicéphore Niépce World’s first photograph

1826

slide8

The First Photomicrograph

John Benjamin Dancer

1812-1887

In 1840, he showed first photomicrograph (actually a Daguerreotype) of a Flea using a gas illuminated microscope and a camera lucida.

slide10

In the mid-1800’s photographers learned to apply a silver halide emulsion to glass plates. These “negatives” could then be used multiple times to create many photographs of a single image.

slide11

Until the 1960’s all TEMs also used glass plates for capturing images. The scientists would have to apply the emulsion to the plates themselves as these did not come ready made from the manufacturer.

slide12

SEM of silver halide grains

Modern photography still uses silver halide grains embedded in an emulsion but the base is no longer made of glass.

slide14

Some of the halide grains will become exposed due to the energy of the transmitted electrons striking them. Upon development these exposed grains become deposited as metallic silver. This is the “latent” image. After fixation unexposed (and thus undeveloped) silver grains are removed from the emulsion by a process known as fixation.

slide15

A black and white photograph is nothing more than a two dimensional arrangement of black (silver grains) and white (paper backing from which grains have been removed) arranged in such a way that they create an image.

slide16

Image Processing:

Optical: Mechanical manipulation

(lenses, enlargers, etc.)

Analog: Electronic manipulation

Digital: Computer manipulation:

Image as a data matrix

slide17

Image Processing:

Optical: Brightness, contrast, enlargement,

cropping, dodging & burning

Analog:

Digital:

slide18

Image Processing:

Optical: Brightness, contrast, enlargement,

cropping, dodging & burning

Analog: Brightness, contrast.

Digital:

slide19

Image Processing:

Optical: Brightness, contrast, enlargement,

cropping, dodging & burning

Analog: Brightness, contrast.

Digital: Brightness, contrast, enlargement,

cropping, dodging & burning, non-

linear display, contrast stretching,

erosion & dilation, edge

enhancement, etc.

slide20

Contrast vs. Brightness

Brightness: The location of a visual perception along the black to white continuum

Bright

Dark

slide21

Contrast vs. Brightness

Contrast: The range of optical density and tone on a photographic image (or the extent to which adjacent areas on a CRT differ in brightness.

High

Low

slide22

Contrast vs. Brightness

As contrast is increased the overall brightness of the image appears to increase in some areas and decrease in others

slide23

In photographic image processing brightness is modified by exposure which is a function of illumination intensity X time. The longer the time and/or the more intense the illumination the brighter the image will be.

In analog processing brightness is increased by increasing the signal going to each pixel

In digital processing brightness is increased by increasing the numerical value of each pixel by an equal amount.

slide24

In photographic image processing contrast is controlled by the size of silver grains in the emulsion, the larger the grains the greater the contrast.

In analog processing contrast is increased by varying the ranges of signal to each pixel.

In digital processing contrast is increased by expanding the differences in numerical values between the maximum and minimum pixels.

slide25

Image Processing:

Optical: Stored as negatives (original) or

prints (second generation)

Analog: Stored as video (original) or copy (second generation)

Digital: Stored as computer data file (original and multiple copies all first generation)

slide26

Image Processing:

Optical: Transmitted by distribution of prints (second generation) or publication (fourth generation)

Analog: Transmitted by distribution of video tapes (second generation) or broadcast (third generation)

Digital: Transmitted by file copying and transfer (all first generation)

slide27

Digital Imaging:

A digital image is nothing more than a data matrix that assigns both a value and a location to each picture element (pixel) in the image

slide28

Digital Imaging:

When considering the “resolution” of a digital image we need to consider both of these aspects; value of the pixel and its position in the data matrix

slide29

Digital Imaging:

“Spatial” resolution is defined as the number of pixels used to create the image or more simply the total number of pixels in the matrix.

slide30

Spatial Resolution:

100 x 200 25 x 50 13 x 25 3 x 6

Pixel resolution is typically given as X x Y

slide31

Spatial Resolution:

100 x 200 25 x 50 13 x 25 3 x 6

More is BETTER!

slide32

A digital image from a typical SEM or TEM is often 2K x 2K format whereas a photographic negative from a TEM is closer to 8K x 6K if one were to count silver grains as pixels.

slide33

Pixels vs. Dots per Inch

Pixel resolution refers to the number of pixels that comprise the image regardless of how large the image is. A typical computer monitor has a 1024 x 768 pixel resolution whether it is a 15” or 21”

Dots per Inch or “DPI” refers to the number of pixels per linear inch in the final image. Thus the DPI of a given image decreases as the size of the final image increases.

slide34

Digital Imaging:

“Grey level” resolution refers to the range of values that each pixel might have. The greater the value range, the greater the grey level resolution.

slide35

Grey Level Resolution:

Bit = a unit of binary information either a “0” or a “1”

Byte = a string of eight bits

KiloByte = 1000 Bytes or 8000 bits

MegaByte = 1000 KB

slide36

Grey Level Resolution:

One bit can code for only two values or states (0) or (1)

Two bits can code for four states: (0,0) (0,1) (1,0) or (1,1)

Three bits for eight and so on....

One Byte can code for 28 or 256 different states (0,0,0,0,0,0,0,0) (0,0,0,0,0,0,0,1)...

slide37

This is often referred to as the “bit depth” of an image and it limits the range of pixel values that can be displayed in the image.

1 8 24

slide38

Shades of Grey

The average human eye can perceive fewer than 100 different shades of grey between absolute white and absolute black. Thus an 8-bit image, with a possible 256 different levels of grey is more than sufficient to display any typical B&W image.

slide39

Range of Color:

Color digital images can also be based on

8-bit format but in this case a total of three separate pixels (Red, Green, & Blue) are combined for a 24 bit-depth range of colors.

28 x 28 x 28 = 224 =

RGB

16,777,216 different colors

slide40

This is sufficient to render very sophisticated and realistic graphics. The latest Nintendo Game Cube advertises a pixel depth with 24-bit color.

slide41

The best digital capture devices are capable of capturing images in 12 or even 16-bit (216) grey scale format and are cooled to reduce the effects of noise from the electronics.

Micro Luminetics Cryocam

slide42

The data storage demands increase dramatically depending on the spatial and grey-scale resolution:

512 x 512 8-bit image = 262 KB

1024 x 1024 8-bit = 1,049 KB

1024 x 1024 12-bit = 1,573 KB

2048 x 2048 16-bit = 8,389 KB

slide43

Grey Level Resolution:

The number of possible pixel values increases dramatically with relatively modest demands on data storage.

8-bit image 256 shades of grey

12-bit image 4096 shades of grey

16-bit image 65,536 shades of grey

slide45

Bit-depth can be an important aspect of color images. The human eye can discern many different colors and hues so the “dynamic range” of a color image is important.

slide46

Bit-depth can be an important aspect of color images. The human eye can discern many different colors and hues so the “dynamic range” of a color image is important.

But Electron Microscopy is B&W

so who cares!