For the last few activities we've been learning how to do image processing with the Pixel Calculator. In this lesson you will pretend to be the computer and do the Image Processing yourself. All of these answers are to be answered without using the computer.
What is the highest value a pixel in the Pixel Calculator can have?
What color is a pixel with the highest value?
What is the lowest value a pixel in the Pixel Calculator can have?
What color is a pixel with the lowest value?
What is a pixel value which would look gray on the screen?
Fill in the blanks below. The first one is completed as an example.
Regular With Pixel Values 15 - 14 15 - 16 150 + 107 0 * 128 1 * 128 3 * 128
The next couple of questions use this picture from the Pixel Calculator.
What is the value of pixel (7. 10)
What are the coordinates of the pixel with value 102?
An example rectangle has been drawn on the picture above for ((5, 7)-(9, 8)). What is the area of that rectangle? (Hint: count the squares)
Now you draw one on the picture above for ((2, 6)-(8, 11)).
What is the area of the rectangle you drew?
Now try the same things in the Pixel Calculator on the real copy of the image.
Load the file small.bmp by selecting File and then Get Image,.
You'll have to zoom in to answer these questions.
What is the value of pixel (11, 7)
Now draw a rectangle from (2, 6) to (8, 11)). Do the operation 255 - #, then press the Compute button. Fill in the grid below with the values from the computer in the rectangle.
There is actually a secret message hidden in small.bmp. Let's find it.
First, find the value of pixel (4, 19). This is a secret message pixel.
What is the gray value of the secret message pixel?
Draw a selection rectangle around ((0,19)-(11,21)). Then use subtraction to make all lower valued pixels 0 (Hint: # - ) Now use multiplication to make all higher valued pixels 255 (hint: # *
What is the secret message?
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