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Subject : T0934 / Multimedia Programming FoundationSession : 5Tahun : 2009Versi : 1/0

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Learning Outcomes

In the end of this session, students must be able to: – Understand the basic principal

of image transformation and enhancement

– Apply correct Java syntax to transform, enhance, and display an image

Course Outlines

• Digital Image Definition• Image Transformation• Image Enhancement• Java 2D API

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Digital Image Definition

• Image array of pixel Z(x,y)

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N

M

Z

X = width (0 – N)Y = height (0 – M) Z = pixel values

X = width (0 – N)Y = height (0 – M) Z = pixel values

X

Y

0

Digital Image Definition

• Image Z(x,y)• Z refers to RGB values or brightness

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Image Transform in Java

• drawImage– draw and scale an image

• ConvolveOp – blur or sharpen an image

• AffineTransformOp – transform an image

• Graphics2D.setClip – crop an image

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Image Enhancement in Java

•LookupOp– remap pixel colors (ex : a negative

image)

•RescaleOp – lighten/darken or reduce/increase

opacity of the image

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drawImage

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This is an example to draw image with Java2D

Image Transformation

newZ (x,y) = F(Z(x,y))= result of a Function

based on originalZ(x,y)

Horizontal Flipping x’ = N – xy’ = y

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Image Transformation

• Vertical Flippingx’ = xy’= M - y

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Image Transformation

• Rotation

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x' cos a -sin a 0 x y' = sin a cos a 0 y z' 0 0 1 Z

a

Matrix / KernelMatrix / Kernel

Image Rotation

• The basic algorithm is not used in practice– contains unwanted gaps or holes usually requires a greater

number of pixels than the source to properly display the rotation

• Therefore, interpolation is used to solve this problemBina Nusantara

Gaps/holesGaps/holes

Image Interpolation

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Interpolation

InterpolationInterpolation

using known data to estimate values at

unknown points.

using known data to estimate values at

unknown points.

Image Transformation

• Cropping

• Scale• Shear

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AffineTransformOp

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Rotate

Full codes are downloadable in Additional Material

AffineTransformOp

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Shear

Full codes are downloadable in Additional Material

AffineTransformOp

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Scale

Full codes are downloadable in Additional Material

AffineTransformOp

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Translate

Full codes are downloadable in Additional Material

Scale

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x’

y’

1

sx 0 0

0 sy 0

0 0 1

x

y

1

= *

RescaleOp

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Rescaling

Full codes are downloadable in Additional Material

Shear

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x’

y’

1

1 h 0

0 1 0

0 0 1

x

y

1

= *

Image Enhancement

Convolution • an operation in which the final pixel is the weighted sum of

the neighboring pixels• Use matrix/kernel as well convolution kernel / linear filter

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Convolution

• Blurring

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1 2 12 4 21 2 1

XYZ

Note : This is only an example of many blur kernel variations

Convolution

• Sharpening

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-1 -1 -1-1 9 -1-1 -1 -1

XYZ

Note : This is only an example of many sharpen kernel variations

Convolution

• Edge Detection

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-1 -1 -1-1 8 -1-1 -1 -1

XYZ

Note : This is only an example of many edge detection kernel variations

ConvolveOp

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Blur Full codes are downloadable in Additional Material

ConvolveOp

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Sharpen Full codes are downloadable in Additional Material

ConvolveOp

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Edge Full codes are downloadable in Additional Material

Image Enhancement

• Brighten/Darken

• Opacity

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Brighten Darken

Opacity 80% Opacity 50%

Graphics2D.setClip

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setClip is used to clip a portion of images to make a new image

LookupOp

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Invert Color

Full codes are downloadable in Additional Material

References

• Image Processing with Java 2D. 2008. http://www.javaworld.com/javaworld/jw-09-1998/jw-09-media.html?page=3

• Image Processing and Enhancement. 1999. http://java.sun.com/j2se/1.3/docs/guide/2d/spec/j2d-image.fm8.html

• Image Processing Fundamentals. 2009. http://www.ph.tn.tudelft.nl/Courses/FIP/noframes/fip.html

• Basic Concepts in Digital Image Processing. 2004. http://micro.magnet.fsu.edu/primer/digitalimaging/javaindex.html

• The Digital Darkroom. 2003. http://www.spinroot.com/pico/a3.pdf• Transforming Shapes, Text, and Images. 2008.

http://java.sun.com/docs/books/tutorial/2d/advanced/transforming.html• Digital Image Interpolation. 2009.

http://www.cambridgeincolour.com/tutorials/image-interpolation.htm• Image Convolution. 2009. http://www.eas.asu.edu/~karam/2dconvolution/• Image Filtering with GLSL - Convolution Kernels. 2009.

http://www.ozone3d.net/tutorials/image_filtering.php• Fundamentals of Image Processing. 2009.

http://www.cs.dartmouth.edu/~farid/tutorials/fip.pdf

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