Opening Exercise Write a method that turns pixels with an average - - PowerPoint PPT Presentation

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opening exercise write a method that turns pixels with an
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Opening Exercise Write a method that turns pixels with an average - - PowerPoint PPT Presentation

Dec 24, 2023 248 likes •369 views

Opening Exercise Write a method that turns pixels with an average intensity less than 85 to GREEN, pixels with an average intensity less than 170 to RED, and all other pixels to BLUE. What Is Wrong With This Answer? public void exercise01()

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SLIDE 1

Opening Exercise Write a method that turns pixels with an average intensity less than 85 to GREEN, pixels with an average intensity less than 170 to RED, and all other pixels to BLUE.

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SLIDE 2

What Is Wrong With This Answer?

public void exercise01() { for ( Pixel p : this.getPixels() ) { double averageIntensity = p.getAverage(); if ( averageIntensity < 85 ) p.setColor( Color.green ); if ( averageIntensity < 170 ) p.setColor( Color.red ); if ( averageIntensity < 256 ) p.setColor( Color.blue ); } }

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SLIDE 3

Guarded Action

manipulate a pixel

  • nly if

it satisfies a particular condition the if statement if ( condition is true ) take the action

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SLIDE 4

Alternative Action

Idea manipulate a pixel in one way if it satisfies a particular condition

  • r in another way

if it satisfies a particular condition

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SLIDE 5

Alternative Action

Implementation the if-else statement if ( condition is true ) take one action else take the other action

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SLIDE 6

Range Selection

Using nested if-else statements to find ranges: if ( value is in the first range ) take the first action else if ( value is in the second range ) take the second action ... else take the final action

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SLIDE 7

One Hallmark of Good Design

"When making a design choice, always have at least two

  • alternatives. That way, you can at least know that you are

not doing the worst possible thing." — paraphrased from Kent Beck

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SLIDE 8

Finding Objects in Images

Boundaries appear when neighboring pixels have very different colors. This is the task of edge detection.

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SLIDE 9

An Application of Edge Detection computer vision

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SLIDE 10

Boolean Conditions

if ( condition is true ) ... simple boolean expression x < y p.colorDistance(epsilon) conjunction (and) x < y && p.colorDistance(epsilon) disjunction (or) x < y || p.colorDistance(epsilon)

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SLIDE 11

Homework 2

What are the high-level operations?

  • insert the image
  • draw a box (several times)
  • draw a horizontal line
  • draw a vertical line

Design your solution in this way:

  • create an empty method for each operation
  • design, implement, and test each method one at a

time