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slide1

This work is licensed under the Creative Commons Attribution-Noncommercial 2.5 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/2.5/ or send a letter to Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 94105, USA.

Digital Image Processing

Lecture Notes: Introduction and Overview

Dr. Chung-Hao Chen

Department of Electrical and Computer Engineering

Old Dominion University

Courtesy of

Dr. Richard Alan Peters II

Department of Electrical Engineering and Computer Science

Vanderbilt University

introduction and overview
Introduction and Overview

This presentation is an overview of some of the ideas and techniques to be covered during the course.

1999-2011 by Richard Alan Peters II

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Topics

1. Image formation

2. Color correction

3. Image sampling, warping, and stitching

4. Spatial filtering

5. Noise reduction

6. High dynamic range imaging

7. Image compression

1999-2011 by Richard Alan Peters II

slide4

lens

object

image plane

Image Formation

1999-2011 by Richard Alan Peters II

slide5

light source

Image Formation

1999-2011 by Richard Alan Peters II

slide6

Image Formation

projection

through lens

image of object

1999-2011 by Richard Alan Peters II

slide7

Image Formation

projection onto discrete sensor array.

digital camera

1999-2011 by Richard Alan Peters II

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Image Formation

sensors register average color.

sampled image

1999-2011 by Richard Alan Peters II

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Image Formation

continuous colors, discrete locations.

discrete real-valued image

1999-2011 by Richard Alan Peters II

digital image formation quantization
Digital Image Formation: Quantization

discrete color output

continuous colors mapped to a finite, discrete set of colors.

continuous color input

1999-2011 by Richard Alan Peters II

digital image
Digital Image

Color images have 3 values per pixel; monochrome images have 1 value per pixel.

a grid of squares, each of which contains a single color

each square is called a pixel (for picture element)

1999-2011 by Richard Alan Peters II

color images
Are constructed from three intensity maps.

Each intensity map is pro-jected through a color filter (e.g., red, green, or blue, or cyan, magenta, or yellow) to create a monochrome image.

The intensity maps are overlaid to create a color image.

Each pixel in a color image is a three element vector.

Color Images

1999-2011 by Richard Alan Peters II

color processing
Color Processing

requires some knowledge of how we see colors

1999-2011 by Richard Alan Peters II

eye s light sensors

cone density near fovea

#(blue) << #(red) < #(green)

Eye’s Light Sensors

1999-2011 by Richard Alan Peters II

color sensing color perception
Color Sensing / Color Perception

These are approximations of the responses to the visible spectrum of the “red”, “green”, and “blue” receptors of a typical human eye.

1999-2011 by Richard Alan Peters II

color sensing color perception1
Color Sensing / Color Perception

These are approximations of the responses to the visible spectrum of the “red”, “green”, and “blue” receptors of a typical human eye.

The simultaneous red + blue response causes us to perceive a continuous range of hues on a circle. No hue is greater than or less than any other hue.

1999-2011 by Richard Alan Peters II

color sensing color perception2
Color Sensing / Color Perception

The eye has 3 types of photoreceptors:

sensitive to red, green, or blue light.

luminance

hue

saturation

The brain transforms RGB into separate brightness and color channels (e.g., LHS).

brain

photo receptors

1999-2011 by Richard Alan Peters II

color perception

luminance and chrominance (hue+saturation) are perceived with different resolutions, as are red, green and blue.

16×pixelization of:

Color Perception

chrominance

luminance

all bands

blue

green

red

1999-2011 by Richard Alan Peters II

rotation
Rotation

and motion blur

1999-2011 by Richard Alan Peters II

image warping
Image Warping

1999-2011 by Richard Alan Peters II

panorama via overlay
Panorama via Overlay

Originals

Bruno Postle http://hugin.sourceforge.net/tutorials/two-photos/en.shtml

Merged*

1999-2011 by Richard Alan Peters II

*not so good.

panorama via stitching
Panorama via Stitching

Originals

Bruno Postle http://hugin.sourceforge.net/tutorials/two-photos/en.shtml

Merged*

1999-2011 by Richard Alan Peters II

*much better.

spatial filtering
Spatial Filtering

blurred

original

sharpened

1999-2011 by Richard Alan Peters II

spatial filtering1
Spatial Filtering

bandpass

filter

unsharp

masking

original

1999-2011 by Richard Alan Peters II

spatial filtering2
Spatial Filtering

signed image with

0 at middle gray

bandpass

filter

unsharp

masking

original

1999-2011 by Richard Alan Peters II

motion blur
Motion Blur

regional

vertical

original

rotational

zoom

1999-2011 by Richard Alan Peters II

noise reduction

blurred image

color-only blur

color noise

Noise Reduction

1999-2011 by Richard Alan Peters II

noise reduction1

blurred image

color noise

Noise Reduction

5x5 Wiener filter

1999-2011 by Richard Alan Peters II

noise reduction2
Noise Reduction

periodic

noise

frequency

tuned filter

original

1999-2011 by Richard Alan Peters II

shot noise or salt pepper noise

+ shot noise

s&p noise

- shot noise

Shot Noise or Salt & Pepper Noise

1999-2011 by Richard Alan Peters II

nonlinear filters the median

original

s&p noise

median filter

Nonlinear Filters: the Median

1999-2011 by Richard Alan Peters II

nonlinear filters min and maxmin

+ shot noise

min filter

maxmin filter

Nonlinear Filters: Min and Maxmin

1999-2011 by Richard Alan Peters II

nonlinear filters max and minmax
Nonlinear Filters: Max and Minmax

- shot noise

max filter

minmax

1999-2011 by Richard Alan Peters II

high dynamic range hdr imaging
High Dynamic Range (HDR) Imaging

Bartlomiej Okonek http://www.easyhdr.com/examples.php

under exposed

1999-2011 by Richard Alan Peters II

high dynamic range hdr imaging1
High Dynamic Range (HDR) Imaging

Bartlomiej Okonek http://www.easyhdr.com/examples.php

default exposure

1999-2011 by Richard Alan Peters II

high dynamic range hdr imaging2
High Dynamic Range (HDR) Imaging

Bartlomiej Okonek http://www.easyhdr.com/examples.php

over exposed

1999-2011 by Richard Alan Peters II

high dynamic range hdr imaging3
High Dynamic Range (HDR) Imaging

Bartlomiej Okonek http://www.easyhdr.com/examples.php

combined

1999-2011 by Richard Alan Peters II

image compression
Image Compression

Original image is 5244w x 4716h @ 1200 ppi: 127MBytes

Yoyogi Park, Tokyo, October 1999. Photo by Alan Peters.

1999-2011 by Richard Alan Peters II

image compression jpeg
Image Compression: JPEG

File size in bytes

JPEG quality level

1999-2011 by Richard Alan Peters II

image compression jpeg1
Image Compression: JPEG

File size in bytes

JPEG quality level

1999-2011 by Richard Alan Peters II

image compositing
Image Compositing
  • Combine parts from separate images to form a new image.
  • It’s difficult to do well.
  • Requires relative positions, orientations, and scales to be correct.
  • Lighting of objects must be consistent within the separate images.
  • Brightness, contrast, color balance, and saturation must match.
  • Noise color, amplitude, and patterns must be seamless.

1999-2011 by Richard Alan Peters II

image compositing example
Image Compositing Example

Prof. Peters in his home office. Needs a better shirt.

1999-2011 by Richard Alan Peters II

image compositing example1
Image Compositing Example

This shirt demands a monogram.

1999-2011 by Richard Alan Peters II

image compositing example2
Image Compositing Example

He needs some more color.

1999-2011 by Richard Alan Peters II

image compositing example3
Image Compositing Example

Nice. Now for the way he’d wear his hair if he had any.

1999-2011 by Richard Alan Peters II

image compositing example4
Image Compositing Example

He can’t stay in the office like this.

1999-2011 by Richard Alan Peters II

image compositing example5
Image Compositing Example

Where’s a hepcat Daddy-O like this belong?

1999-2011 by Richard Alan Peters II

image compositing example6
Image Compositing Example

Collar this jive, Jackson. Like crazy, Man !

In the studio!

1999-2011 by Richard Alan Peters II