Enlarging pictures

1
Session 14

• Enlarging pictures

2
What can I do when things arent the size I want?

• Scaling Up Last time I taught this class I had
  a student during Lab 5 with a photo of Paris
  Hilton. She wanted to make it bigger so she could
  put a pigs head on her body.

3
Thinking Through Scaling Up
0
1
2

• Copy each pixel in the source multiple times to
  the target
• Source (0,0) Target (0,0)
• Source (0,0) Target(1,0)
• Source (1,0) Target(2,0)
• Source (1,0) Target(3,0)
• Source (2,0) Target(4,0)
• Source (2,0) Target(5,0)
• Source (0,0) Target(0,1)
• Source (0,0) Target(1,1)

0
1
0
1
2
3
4
5
0
1
2
3
4

• def scaleUpBlocks(sourcePicture)
• w getWidth(sourcePicture)2
• h getHeight(sourcePicture)2
• newPicture makeEmptyPicture(w,h)
• for x in range(1,getWidth(sourcePicture)1)
• for y in range(1,getHeight(sourcePicture)1)
  
• source getPixel(x,y)
• target getPixel(x2,y2)
• setColor(target,getColor(source))
• target getPixel(x2-1,y2)
• setColor(target,getColor(source))
• target getPixel(x2-1,y2-1)
• setColor(target,getColor(source))
• target getPixel(x2,y2-1)
• setColor(target,getColor(source))
• return newPicture

5
Can you think of a less blocky way to do this?

• Average two adjoining Pixels to come up with a
  brand new Pixel between them
• Has strengths and weaknesses as an overall
  solution

6
Another way to Scale Up
0
1
2

• Copy each pixel in the source only once.

0
1
2
0
1
3
4
0
1
2
7
Another way to Scale Up
0
1
2

• Copy each pixel in the source only once.
• For the remaining empty pixels, insert the
  average of the two neighbor pixels.

0
1
2
0
1
3
4
0
1
2