We’ll be using jes (Jython Environment for Students). We’ll be using jes

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We’ll be using JES (Jython Environment for Students).

We’ll be using JES (Jython Environment for Students).
Install the version JES 4.3 (Jython environment for students) available as free download: http://code.google.com/p/mediacomp-jes/

Anything you type in command area is evaluated and its value is displayed

Anything you type in command area is evaluated and its value is displayed
Example:

Up/down arrows walk through command history

Up/down arrows walk through command history
You can edit the line at the bottom

Just put the cursor at the end of the line before hitting Return/Enter.

JES defines some special functions for media computation

JES defines some special functions for media computation

makeEmptyPicture(width,height) creates a new empty picture

makeEmptyPicture(width,height) creates a new empty picture
show(picture) displays a picture in a separate window

>>> pic1 = makeEmptyPicture(200,100)
>>> show(pic1)
>>> setAllPixelsToAColor(pic1, red)
>>> show(pic1)
>>> addText(pic1,30,50,“hello")

similarly can add rectangles, lines, etc.

The JES Functions menu has functions arranged by type - check them out!

The JES Functions menu has functions arranged by type - check them out!
Can you find a function that saves a file?
Can you find under what category pickAFile() is listed?

Create a function that…

Create a function that…

Causes an interactive input window to pop up and request some form of input from the user and stores it in a variable
Displays the value stored in the variable
Displays an image

Save your function in a file
Load it
Use the function in the command area to make sure that it works and does what you want it to do

makePicture(filename) creates and returns a picture object, from the .JPG or .PNG file at the filename

makePicture(filename) creates and returns a picture object, from the .JPG or .PNG file at the filename
We’ll learn functions for manipulating pictures later, like getColor(), setColor(), and repaint()

Some names for common colors are predefined – try using the names: yellow, black, white, etc.

Some names for common colors are predefined – try using the names: yellow, black, white, etc.
makeColor() takes red, green, and blue values (in that order) between 0 and 255, and returns a Color object
pickAColor() lets you use a color chooser and returns the chosen color

Colors go from

Colors go from
(0,0,0) to (255,255,255)

setMediaPath(): Prompts the user to pick a folder on the computer. JES then will look for files in that directory unless given a full path, i.e. one that starts with "c:\"

setMediaPath(): Prompts the user to pick a folder on the computer. JES then will look for files in that directory unless given a full path, i.e. one that starts with "c:\"
writePictureTo(picture, path): picture: the picture you want to be written out to a file path: the path to the file you want the picture written to Takes a picture and a file name (string) as input, then writes the picture to the file as a JPEG.
Example:
>>> setMediaPath()
writePictureTo(pic, “mypic.jpg”)

if age < 18:

if age < 18:
showInformation(“Sorry, not allowed to vote yet.”)
else:
showInformation(“Please select candidate.”)

for number in range(0,N):

for number in range(0,N):
pic = ....
filename = base + str(number)
writePictureTo(pic, filename)

[“hi”, “hello”, “howdy”, “hiya”, “yo”]

[“hi”, “hello”, “howdy”, “hiya”, “yo”]
[10, 23, 15]
[]
range(0,6)
range(1,4)
range(3,8)

Create a function makeMeSwatches() that makes lots of color swatches (small solid-colored image files). Specifically, your function should:

Create a function makeMeSwatches() that makes lots of color swatches (small solid-colored image files). Specifically, your function should:
display a welcome message to the user
ask the user to say how many swatches
ask the user to select a folder for storing the swatches
create small files with images of solid color save each one in the selected folder with names "swatch0.jpg", "swatch1.jpg", "swatch2.jpg", etc
display a message letting the user know that it is finished.

>>> p = getPixel(picture,12,9)

>>> p = getPixel(picture,12,9)
>>> print p
Pixel, red=108 green=86 blue=142

getRed(p),

getRed(p),
getGreen(p)
getBlue(p)
setRed(p, value)
setGreen(p, value)
setBlue(p, value)

getColor(p) takes a pixel as input and returns a Color object with the color at that pixel

getColor(p) takes a pixel as input and returns a Color object with the color at that pixel
setColor(p, c) sets the color of pixel (p) as input and a color (c), then sets the pixel to that color.
We also have functions that can makeLighter(c) and makeDarker(c) an input color
Last time we saw that we can also create colors:

makeColor(r,g,b) takes red, green, and blue values (in that order) between 0 and 255, and returns a Color object
pickAColor() lets you use a color chooser and returns the chosen color

>>> pixel=getPixel(picture,12,9)

>>> pixel=getPixel(picture,12,9)
>>> print pixel
Pixel, red=108 green=86 blue=142
>>> value = getRed(pixel)
>>> setRed (pixel, value+50)
>>> setGreen(pixel, 0)
>>> setBlue(pixel, getBlue(pixel)/2)

>>> pixel=getPixel(picture,12,9)

>>> pixel=getPixel(picture,12,9)
>>> print pixel
Pixel, red=108 green=86 blue=142
>>> value = getRed(pixel)
>>> setRed (pixel, value+50)
>>> setGreen(pixel, 0)
>>> setBlue(pixel, getBlue(pixel)/2)

>>> pixel=getPixel(picture,12,9)

>>> pixel=getPixel(picture,12,9)
>>> print pixel
Pixel, red=108 green=86 blue=142
>>> redValue = getRed(pixel)
>>> greenValue = getGreen(pixel)
>>> blueValue = getBlue(pixel)
>>> newColor = makeColor(redValue+50, 0, getBlue(pixel)/2)
>>> setColor(pixel, newColor)

>>> pixel=getPixel(picture,12,9)

>>> pixel=getPixel(picture,12,9)
>>> print pixel
Pixel, red=108 green=86 blue=142
>>> redValue = getRed(pixel)
>>> greenValue = getGreen(pixel)
>>> blueValue = getBlue(pixel)
>>> newColor = makeColor(redValue+50, 0, getBlue(pixel)/2)
>>> setColor(pixel, newColor)

Example:
for p in getPixels(picture): value = getRed(p) setRed(p, value*0.5)

Example:
def decreaseRed(picture):
for p in getPixels(picture): value = getRed(p) setRed(p, value*0.5)

More examples (link) - you can copy and paste these to save time

More examples (link) - you can copy and paste these to save time
decreaseGreen()
decreaseBlue()
clearBlue()
lighten()
darken()
negative()
grayScale()

Create a menu-driven picture manipulation function that allows the user to make various changes to images. Here is the algorithm:

Create a menu-driven picture manipulation function that allows the user to make various changes to images. Here is the algorithm:
welcome the user to your program
get the user to select a picture to work on
show(picture)
ask the user select one of the following options:

Make picture grayscale
Decrease red by 10%
Decrease green by 10%
Decrease blue by 10%
“Posterize” (see below)

repaint(picture)
ask user whether to save the new picture, and if the response is “y”, save it
show goodbye/thank you message
Links to small images you can use to test your program: eye.jpg, luca.jpg

Example:

Example:
requestIntegerInRange(“Please enter one of the following
…
requestIntegerInRange(“Please enter one of the following options: 1) grayscale, 2) reduce red,
…
requestIntegerInRange(“Please enter one of the following options: 1) grayscale, 2) reduce red, 3) reduce green, 4) reduce blue, 5) posterize”)
…

Special characters that cannot be used directly as part of a string, eg:

Special characters that cannot be used directly as part of a string, eg:
\n – new line
\t – tab
\\ – backslash (\)
\’ – single quote
Example:
showInformation(“see you\nlater”)

The knowledge that a secret exists is half of the secret -- Joshua Meyrowitz

The knowledge that a secret exists is half of the secret -- Joshua Meyrowitz
From the Greek words στεγανός and γράφω meaning “covered writing.”
Art and Science of hiding information in ways that prevent detection.
Can be used on audio, text, packet headers, or images
Similar to Cryptography –Cryptography: scrambles message –Steganography: hides message

Least Significant Bit (LSB)

Least Significant Bit (LSB)
One of most common techniques
Alters LSB of each pixel (1 bit out of 24 --or 1 out of 8 for grayscale)
Uses the concept of parity, ie, even numbers in binary end in 0, odd ones end in 1
Easiest to implement: hiding bitmaps in a color picture
Hiding ASCII code, one letter at a time

To hide letter C (1000011) in a grayscale file:

To hide letter C (1000011) in a grayscale file:
Original:
01001101 01001110 01001110 01001111 01010000 01010000 01001111
1 0 0 0 0 1 1
Encoded:
01001101 01001110 01001110 01001110 01010000 01010001 01001111

def encode(picture, message): import java.awt.Font as Font myFont = makeStyle("Arial", Font.BOLD, 24) msgPicture = makeEmptyPicture(getWidth(picture), getHeight(picture), white) addTextWithStyle(msgPicture,10,28,message, myFont, black) encodePicture(picture, msgPicture)

def encode(picture, message): import java.awt.Font as Font myFont = makeStyle("Arial", Font.BOLD, 24) msgPicture = makeEmptyPicture(getWidth(picture), getHeight(picture), white) addTextWithStyle(msgPicture,10,28,message, myFont, black) encodePicture(picture, msgPicture)
def encodePicture(picture, msgPicture): for pxl in getPixels(picture): if (getRed(pxl) % 2) == 1: setRed(pxl, getRed(pxl) - 1) for x in range(0, getWidth(picture)): for y in range(0, getHeight(picture)): msgPxl = getPixel(msgPicture, x, y) origPxl = getPixel(picture, x, y) if distance(getColor(msgPxl), black) < 100.0: setRed(origPxl, getRed(origPxl)+1)

Need to determine which pixels have been changed.

Need to determine which pixels have been changed.
No need to have original image – the rightmost bit of the image with the code does not depend on the original
We can thus loop through the pixels and reconstruct the message image

Menu-driven picture manipulation set of functions. Algorithm:

Menu-driven picture manipulation set of functions. Algorithm:

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We’ll be using jes (Jython Environment for Students). We’ll be using jes

We’ll be using JES (Jython Environment for Students).

We’ll be using JES (Jython Environment for Students).

Install the version JES 4.3 (Jython environment for students) available as free download: http://code.google.com/p/mediacomp-jes/

Anything you type in command area is evaluated and its value is displayed

Anything you type in command area is evaluated and its value is displayed

Example:

Up/down arrows walk through command history

Up/down arrows walk through command history

You can edit the line at the bottom

JES defines some special functions for media computation

JES defines some special functions for media computation

makeEmptyPicture(width,height) creates a new empty picture

makeEmptyPicture(width,height) creates a new empty picture

show(picture) displays a picture in a separate window

similarly can add rectangles, lines, etc.

The JES Functions menu has functions arranged by type - check them out!

The JES Functions menu has functions arranged by type - check them out!

Can you find a function that saves a file?

Can you find under what category pickAFile() is listed?

Create a function that…

Create a function that…

Save your function in a file

Load it

Use the function in the command area to make sure that it works and does what you want it to do

makePicture(filename) creates and returns a picture object, from the .JPG or .PNG file at the filename

makePicture(filename) creates and returns a picture object, from the .JPG or .PNG file at the filename

We’ll learn functions for manipulating pictures later, like getColor(), setColor(), and repaint()

Some names for common colors are predefined – try using the names: yellow, black, white, etc.

Some names for common colors are predefined – try using the names: yellow, black, white, etc.

makeColor() takes red, green, and blue values (in that order) between 0 and 255, and returns a Color object

pickAColor() lets you use a color chooser and returns the chosen color

Colors go from

Colors go from

(0,0,0) to (255,255,255)

setMediaPath(): Prompts the user to pick a folder on the computer. JES then will look for files in that directory unless given a full path, i.e. one that starts with "c:\"

setMediaPath(): Prompts the user to pick a folder on the computer. JES then will look for files in that directory unless given a full path, i.e. one that starts with "c:\"

writePictureTo(picture, path): picture: the picture you want to be written out to a file path: the path to the file you want the picture written to Takes a picture and a file name (string) as input, then writes the picture to the file as a JPEG.

Example:

>>> setMediaPath()

writePictureTo(pic, “mypic.jpg”)

if age < 18:

if age < 18:

showInformation(“Sorry, not allowed to vote yet.”)

else:

showInformation(“Please select candidate.”)

for number in range(0,N):

for number in range(0,N):

pic = ....

filename = base + str(number)

writePictureTo(pic, filename)

[“hi”, “hello”, “howdy”, “hiya”, “yo”]

[“hi”, “hello”, “howdy”, “hiya”, “yo”]

[10, 23, 15]

[]

range(0,6)

range(1,4)

range(3,8)

Create a function makeMeSwatches() that makes lots of color swatches (small solid-colored image files). Specifically, your function should:

Create a function makeMeSwatches() that makes lots of color swatches (small solid-colored image files). Specifically, your function should:

display a welcome message to the user

ask the user to say how many swatches

ask the user to select a folder for storing the swatches

create small files with images of solid color save each one in the selected folder with names "swatch0.jpg", "swatch1.jpg", "swatch2.jpg", etc

display a message letting the user know that it is finished.

>>> p = getPixel(picture,12,9)

>>> p = getPixel(picture,12,9)

>>> print p

Pixel, red=108 green=86 blue=142

getRed(p),

getRed(p),

getGreen(p)

getBlue(p)

setRed(p, value)

setGreen(p, value)

setBlue(p, value)

getColor(p) takes a pixel as input and returns a Color object with the color at that pixel

getColor(p) takes a pixel as input and returns a Color object with the color at that pixel

setColor(p, c) sets the color of pixel (p) as input and a color (c), then sets the pixel to that color.

We also have functions that can makeLighter(c) and makeDarker(c) an input color