Week 3

1
Week 3
2
Translating

• Can we put a picture wherever we want it?

3
Another Useful Tool

• makeEmptyPicture(width, height)
• Can you guess what it does?
• Can you guess what it returns?

4
Idea

• Let's make up our own "picture" from scratch!

5
Where?
(xpos, ypos)
6
Last Week

• def drawSquare(posx, posy, picture, redVal)
• for x in range(1, 151)
• for y in range(1, 151)
• xdraw x posx
• ydraw y posy
• b x 1.7
• g y 1.7
• px getPixel(picture, xdraw, ydraw)
• setColor(px, makeColor(redVal, g, b))

7
Testing It

• blank makeEmptyPicture(750, 750)
• drawSquare(130, 45, blank, 0)
• drawSquare(400,400, blank, 255)
• show(blank)

8
Today
750
750
9
The "Main" Program

• def matrix()
• pic makeEmptyPicture(750, 750)
• r 0.0
• for y in range(1, 602, 150)
• for x in range(1, 602, 150)
• square(pic, x, y, int(r))
• r r 10.625
• printNow(r)
• return pic

10
Note!

• The "main" program returns a picture.
• This is useful.
• It could be hard-coded to save the final picture
  as a file
• As a general rule you want functions to be a
  general purpose and as reusable as possible
• You can always "wrap" a function in another
  function to fulfill a specific purpose

11
All the Colors (Almost)
12
Scaling

• Can we make pictures bigger or smaller?
• Can we stretch them?

13
Scaling

• Want a function that will take in a picture and a
  "scale factor" as parameters and will return a
  new picture scaled by "scale factor"
• Example
• halfsize scale(picture, 0.5)
• doublesize scale(picture, 2.0)
• What are halfsize and doublesize?

14
Scaling!
oldx
newx oldx scalefactor
newx
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Recipe

• Take in picture and scale factor
• Determine size of new picture
• Make a new picture (empty)
• Go through each pixel of new picture (hint 2
  fors)
• Determine pixel in old picture that corresponds
  to new picture and copy color over

16
Scaling!
oldx
newx oldx scalefactor
newx
17
Combining Pictures

• Blending

18

• def blend(pic1, pic2)
• width getWidth(pic1)
• height getHeight(pic2)
• pic3 makeEmptyPicture(width, height)
• for x in range(1, width1)
• factor x1.0/width
• other 1.0 - factor
• other x 1.0/width
• factor 1.0 - other
• for y in range(1, height1)
• r1 getRed(getPixel(pic1, x, y))
• r2 getRed(getPixel(pic2, x, y))
• newr factorr1 otherr2
• g1 getGreen(getPixel(pic1, x, y))
• g2 getGreen(getPixel(pic2, x, y))
• newg factorg1 otherg2
• b1 getBlue(getPixel(pic1, x, y))
• b2 getBlue(getPixel(pic2, x, y))
• newb factorb1 otherb2

19
Combining Pictures

• Background Subtraction

-

20
Combining Pictures

• Chromakey

21
Combining Pictures
22
Homework 3

• Write a function named hw3 in a file named hw3.py
  to create a collage of the same image at least
  four times fit onto the 7x95in blank JPEG. This
  image "7inX95in.jpg" is in the media sources
  folder. (You are welcome to add additional
  images, too.) One of those four copies can be the
  original picture. The other three should be
  modified forms. You can do any of
• Scaling, cropping, or rotating the image,
  shifting or altering colors on the image, and
  making it darker or lighter.

23
Homework 3

• Each of your four images should be in different
  quadrants of the picture. One should be in the
  upper left, the next in the lower left, the next
  in the upper right, and the fourth in the lower
  right. You may use as many other images as you
  with, in any other places, but those four images
  in four different quadrants must be there.

24
Homework 3

• Your single function should make all of this
  happen--all of the effects and compositing must
  occur from the single function hw2(). IT IS
  PERFECTLY OKAY FOR HW2() TO USE OTHER FUNCTIONS!
  When grading we will only setMediaPath() to the
  directory containing your image (or
• images) and then execute hw2()--and will expect
  to see a collage get generated.
• In other words hw2() must not take any arguments!

25
Homework 3

• Turn in your code, your original image (or
  images), and your resultant image into WebWork as
  hw3
• Note this means that you must run your code and
  generate the final image and save it to a file to
  be turned in!

26
Hints

• Test your code before turning it in!
• Do not make changes after testing!
• Make sure you turn in all files required
• Read, understand and follow the instructions!
• NOTE Your submissions will be displayed at the
  OMED Banquet for everyone to see!

27
Sound

• pickAFile()
• makePicture(file)
• getPixels(picture)
• getPixel(picture, x, y)
• getRed(pixel)
• getWidth(pic)
• writePictureTo(pic, file)
• setRed(pixel, value)

• pickAFile()
• makeSound(file)
• getSamples(sound)
• getSampleObjectAt(sound,1)
• getSampleValueAt(sound, index
• getLength
• getSamplingRate
• writeSoundTo(sound,file.wav)
• setSample(sample,value)
• getSample(sample)