Mobile CSP Unit 3
Another type of error detection is a check sum. Research what a check sum is and then describe it in your own words. Can a check sum identify where an error occurs?
A checksum takes into consideration the total number of 1s of a row or column and sees if it is an even or an odd number. If it is an odd number in a odd parity scheme, then it is zero, if it is an even number then
What are filename extensions? What are they used for?
A filename extension is the 3 letters after the dot at the end of a filename. They are used to indicate how the contents are to be interpreted.
What's the difference between a raster image and an ASCII representation of a text document?
A raster image is an image representation based on a division into pixels and ASCII is a collection of 8 bit codes used to represent a string of symbols/letters
Other than digital images, what might be an example of a computer model? Explain your answer based on the definition of a model.
A video might be an example of a computer model because a video is really a bunch of images attached together and played fast enough so that it looks fluid to the human eye. This fits the definition of a model because a video is a representation of a multitude of photographs in bits.
Explain how the error card trick from the Error Detection lesson uses a parity scheme. Was it an even or odd parity scheme?
An even Parity scheme, the error card trick uses rows and columns to detect if there is an odd number of cards facing up, if there is, then that means that there is an error, or a flipped card in the scheme. If there are two errors, it would be negated and be cancelled out.
(Optional) Explain in your own words the difference between error detection and error correction. Describe how the error correction process used in the video above allows the computer to fix errors.
Error detection is merely just acknowledging that there is a mistake in the coding, while error correction is changing the mistake to the correct code, to either 1 or 0 .
(POGIL) Describe an algorithm for identifying the card that was flipped.
Examine all of the columns to see if there's an odd number of cards facing up, if there is a column identified, examine the rows and repeat the first step. There should be an overlap between the column and row where an odd integer of cards facing up.
Would you rather own a camera (or camera phone) with a higher number of megapixels or lower? Explain.
I would rather own a camera with more megapixels because the more pixels there are in an image, the higher quality it is. (For example, a picture with 200 pixels looks much better than a picture with only 1 pixel)
What are some of the limitations of using parity bits for error detection?
If there is no hamming method used, parity bits cannot detect exactly where the error is located.
What would you have to do to delete a document from your computer so that it could not possibly be read by anyone else?
In order to delete a document so that it could be read by anyone else, you would have to delete it and then execute an "Empty Trash" command, which writes over the old data, effectively obliterating it.
What is lossless representation? What is lossy representation? What are the trade-offs in using each representation?
Is one that allows exactly the same image to be rendered (no data lost) and a lossy representation is one that allows an approximation of the same image to be rendered (some data lost). Lossless representations are nice because no data is lost, but that makes the file size larger and can make it take longer to be interpreted. Lossy representations have smaller file sizes and can be interpreted in a shorter amount of time, but the quality of the document is lesser since some data is lost.
What is metadata? Give an example of how a piece of metadata could be used to increase the usefulness of an image or document.
Metadata is a set of data that describes and gives information about other data. An image may include metadata that describes how large the picture is, the color depth, the image resolution, when the image was created, and other data. A text document's metadata may contain information about how long the document is, who the author is, when the document was written, and a short summary of the document. Metadata is information about an electronic document. An example is the file name or the "last modified date" of the file.
What is a model?
an abstract representation of the original image.
(POGIL) The card "trick" shows that it is always possible to identify the card that was flipped as long as only one card was flipped. Would it be possible always to determine if an error occurred if two cards were flipped?
no, there would be two pairs of overlapping columns or two sections were the rows and columns overlap, but the other cards facing down would ave an even number or vice versa.
What is steganography and what is it used for? Describe in your own words the steganography algorithm used in the activity.
the art of sending secret messages n imperceptible ways. It is used for including secret (but decipherable) messages along with other data so that only a number of specific people can read the secret message.
