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-[Verano 2016 - Ive]
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+[Verano 2016 - Ive - Coralys]
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-Arrays help us to store and work with groups of data of the same type. The data is stored in consecutive memory spaces which can be accessed by using the name of the array and indexes or subscripts that indicate the position where the data is stored. Repetition structures provide us a simple way of accessing the data within an array. In today's laboratory experience you will design and implement simple algorithms for image processing to practice the use of nested loops to manipulate bi-dimensional arrays.
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+Arrays help us store and work with groups of data of the same type. The data is stored in consecutive memory spaces which can be accessed by using the name of the array with indexes or subscripts that indicate the position where the data is stored. Repetition structures provide us a simple way of accessing the data within an array. In today's laboratory experience, you will design and implement simple algorithms for image processing in order to practice the use of nested loops to manipulate bi-dimensional arrays.
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-##Objectives
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+## Objectives
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1. Practice the access and manipulation of data in an array.
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4. Access pixels in an image and break them down into their red, blue, and green components.
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-##Pre-Lab:
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+## Pre-Lab:
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Before coming to the laboratory session you should have:
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4. Studied the concepts and instructions for the laboratory session.
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-5. Taken the Pre-Lab quiz available in Moodle.
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+5. Taken the Pre-Lab quiz, available in Moodle.
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-##Image editing
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+## Image Editing
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In this laboratory experience, you will work with various concepts and basic skills of image editing. We have provided a simple graphical user interface that allows the user to load an image and invert it vertically and horizontally. Your task is to create and implement a function to convert the colored image into an image with gray tones, and another function that converts the colored image into a black and white image.
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-###Pixels
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+### Pixels
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-The smallest element in an image is called a *pixel*. This unit consists of a single color. Since each color is a combination of tones for the primary red, green and blue colors, it is coded as an unsigned integer whose bytes represent the tones of red, green and blue of the pixel (Figure 1). This combination is called the color's *RGB* which is an acronym for "Red-Green-Blue". For example, a pure red pixel has an RGB representation of `0x00ff0000`, while a white pixel has an RGB representation of `0x00FFFFFF` (since the color white is a combination of tones of red, green and blue in all of their intensity).
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+The smallest element in an image is called a *pixel*. This unit consists of a single color. Since each color is a combination of tones for the primary colors red, green and blue, it is coded as an unsigned integer whose bytes represent the tones of red, green and blue of the pixel (Figure 1). This combination is called the color's *RGB* which is an acronym for "Red-Green-Blue". For example, a pure red pixel has an RGB representation of `0x00ff0000`, while a white pixel has an RGB representation of `0x00FFFFFF` (since the color white is a combination of tones of red, green and blue in all of their intensity).
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-`Qt` uses the `QRgb` type to represent `RGB` values. Using certain functions that are described below we can obtains the red, green and blue components of the `QRgb` value of the pixel and manipulate the images.
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+`Qt` uses the `QRgb` type to represent `RGB` values. Using certain functions that are described below we can obtain the red, green and blue components of the `QRgb` value of the pixel and manipulate the images.
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-###Library
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+### Library
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-In today's laboratory experience you will use the `QImage` class. This class permits access to the data in the pixels of an image to manipulate it. The documentation for the `QImage` class can be found in http://doc.qt.io/qt-4.8/qimage.html.
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+In today's laboratory experience you will use the `QImage` class. This class allows access to the data in the pixels of an image to manipulate it. The documentation for the `QImage` class can be found in http://doc.qt.io/qt-4.8/qimage.html.
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The code provided in this project contains the following objects of the `QImage` class:
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* `width()` // returns the integer value for the image's width
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* `height()` // returns the integer value for the image's height
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* `pixel(i, j)` // returns the `QRgb` for the pixel in position `(i,j)`
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-* `setPixel(i,j, pixel)` // modifies the value for the pixel in position `(i,j)` to the value of pixel `QRgb`
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+* `setPixel(i,j, pixel)` // modifies the value for the pixel in position `(i,j)` to the value `QRgb` of pixel
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The following functions are useful to work with data of type `QRgb`:
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![ejemplo.png](images/ejemplo.png)
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- then `originalImage.pixel(2,1)` returns the `rgb` value that represents the color blue ( `0x0000ff`).
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+ then `originalImage.pixel(2,1)` returns the `rgb` value that represents the color blue ( `0x0000ff`).
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3. The following instruction assigns the color red to the pixel in position `(2,3)` in the edited image:
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## Laboratory Session:
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-In today's laboratory experience you will design and implement simple image processing algorithms to practice the use of nested loops and the manipulation of bi-dimensional arrays.
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+In today's laboratory experience, you will design and implement simple image processing algorithms to practice the use of nested loops and the manipulation of bi-dimensional arrays.
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-### Exercise 1 - Understand the provided code
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+### Exercise 1 - Understand the Provided Code
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-#### Instructions:
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+#### Instructions
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1. Load the project `SimpleImageEditor` into `QtCreator`. There are two ways to do this:
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3. You will be working with the `filter.cpp` file. Study the `HorizontalFlip` function in the `filter.cpp` file so you understand how it operates.
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- In the following exercises you will be mainly using the objects `originalImage` and `editedImage` of the `QImage` class. What do you think is the purpose for the `pixel` variable?
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+ In the following exercises, you will be mainly using the objects `originalImage` and `editedImage` of the `QImage` class. What do you think is the purpose for the `pixel` variable?
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-4. The provided code already has the the functionality of the buttons in the graphical user interface programmed. You do NOT have to change anything in this code but we provide the following explanations so you can know a little about how the buttons work. In the `mainwindow.cpp` file, the `lblOriginalImage` and `lblEditedImage` objects correspond to the parts of the interface that identify the original image and the processed image. The buttons
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+4. The provided code already has the functionality of the buttons in the graphical user interface programmed. You do NOT have to change anything in this code, but we provide the following explanations so you can know a little about how the buttons work. In the `mainwindow.cpp` file, the `lblOriginalImage` and `lblEditedImage` objects correspond to the parts of the interface that identify the original image and the processed image. The buttons
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* `btnLoadImage`
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* `btnSaveImage`
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5. Compile and run the program. Test the buttons for `Load New Image` and `Flip Image Horizontally` with the images that you brought so you can validate if the buttons are working.
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-### Exercise 2 - Convert a colored image to an image with gray tones
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+### Exercise 2 - Convert a Colored Image to an Image with Gray Tones
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Image grayscale is an operation that is used to convert a colored image to an image with only tones of gray. To make this conversion the following formula is used in each pixel:
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`gray = (red * 11 + green * 16 + blue * 5)/32 ;` where `red`, `green` and `blue` are the values for the tones of the red, green and blue colors in the pixel of the original colored image, and `gray` will be the assigned color to the red, green, and blue colors in the pixel of the edited image. That is,
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`editedImage.setPixel( i, j, qRgb(gray, gray, gray) )`.
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-#### Instructions:
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+#### Instructions
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1. Using pseudocode, express the algorithm to convert a colored image to an image with only gray tones. The appendix in this document contains some advice about good techniques for writing pseudocode.
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-### Exercise 3 - Convert a colored image to a black and white image ("Thresholding")
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+### Exercise 3 - Convert a Colored Image to a Black and White Image ("Thresholding")
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-Thresholding es an operation that can be used to convert a colored image to an image in black and white. To make this conversion we must decide which colors of the original image will be converted to white pixels and which to black. One simple way of deciding this is to compute the average of the red, green and blue components of each pixel. If the average is smaller than the threshold value, then we change the pixel to black; if not, it's changed to white.
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+Thresholding is an operation that can be used to convert a colored image to an image in black and white. To make this conversion we must decide which colors of the original image will be converted to white pixels and which to black. One simple way of deciding this is to compute the average of the red, green and blue components of each pixel. If the average is smaller than the threshold value, then we change the pixel to black; if not, it's changed to white.
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-#### Instructions:
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+#### Instructions
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1. Using pseudocode, express the thresholding algorithm. Assume that you will use the slider's value as the threshold.
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2. In the program, if the `chkboxThreshold` box is marked, the `applyThresholdFilter` function is invoked. The `applyThresholdFilter` function is also invoked each time that the value of the slider is changed.
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-3. Complete the `ThresholdFilter` function so it implements the threshold algorithm in the colored image using the slider's value as the threshold. If the implementation is correct, the image on the right should be the original image but in black and white. The threshold value is a parameter of the `ThresholdFilter` function. The code provided in `mainwindow.h` has the constants `BLACK` and `WHITE` defined with their hexadecimal values; you can take advantage of this and use them in your code.
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+3. Complete the `ThresholdFilter` function so it implements the threshold algorithm in the colored image using the slider's value as the threshold. If the implementation is correct, the image on the right should be the original image, but in black and white. The threshold value is a parameter of the `ThresholdFilter` function. The code provided in `mainwindow.h` has the constants `BLACK` and `WHITE` defined with their hexadecimal values; you can take advantage of this and use them in your code.
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4. The boolean parameter `invertColor` will be `true` if the option to invert the colors has been selected. Write the code so that the white and black colors are inverted if `invertColor` is `true`.
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-##Deliverables
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+## Deliverables
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-Use "Deliverable" in Moodle to upload the `filter.cpp` file that contains the `GreyScale` and `Threshold` functions. Remember to use good programming techniques, include the names of the programmers involved, and to document your program.
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+Use "Deliverable" in Moodle to upload the `filter.cpp` file that contains the `GreyScale` and `Threshold` functions. Remember to use good programming techniques, include the names of the programmers involved, and document your program.
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-##Appendix: Good techniques for writing pseudocode
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+## Appendix: Good Techniques for Writing Pseudocode
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-1. Provide a description of the input and output data
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-2. Enumerate the steps
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-3. Use common repetition and decision structures: `if, else, for, while`
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-4. Indent the blocks of steps that are inside of a decision or repetition structure, "Python-style"
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-5. You do not need to declare the types of variables but you should initialize them. This is especially important for counters and accumulators
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+1. Provide a description of the input and output data.
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+2. Enumerate the steps.
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+3. Use common repetition and decision structures: `if, else, for, while`.
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+4. Indent the blocks of steps that are inside of a decision or repetition structure, "Python-style".
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+5. You do not need to declare the types of variables, but you should initialize them. This is especially important for counters and accumulators.
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6. Remember that the purpose of pseudocode is so a human can understand it.
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**Example:**
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-##References
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+## References
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[1] http://www.willamette.edu/~gorr/classes/GeneralGraphics/imageFormats/24bits.gif
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