OPENING QUESTION:
Open a .jpg using our hexedit tool.
Tell the person next to you the vertical/horizontal resolution of that image (You'll probably need our map from last week).
LEARNING OBJECTIVE:
- I will be able to analyze a jpg image file format using a hex editor to find the dimensions of that image during today's class
- I will be able to explain the concept of data compression during today's class
CALENDAR:
WORDS FOR TODAY:
I STRONGLY URGE YOU TO START A DECK OF FLASH CARDS HERE
- innovation: "A new or improved idea, device, product, etc, or the development thereof
- prototype: "A proof of concept"
- CPU: Central Processing Unit
- Binary: 0's & 1's - Base2
- Octal: Base8
- Hexadecimal Base16 - 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
- Byte: one binary 'word'
- Bit: one binary 'letter' - either a 0 or 1
- Abstraction: "The difference between the user layer and the software/hardware layer"
- Compress - to decrease the number of bits used to represent a piece of information
Heuristic - a problem solving approach (algorithm) to find a satisfactory solution where finding an optimal or exact solution is impractical or impossible.
Lossless Compression - a data compression algorithm that allows the original data to be perfectly reconstructed from the compressed data.
Lossy Compression - a data compression algorithm that sacrifices some amount of the original data to decrease file size
Image - A type of data used for graphics or pictures.
metadata - is data that describes other data. For example, a digital image may include metadata that describe the size of the image, number of colors, or resolution.
Pixel - short for "picture element", the fundamental unit of a digital image, typically a tiny square or dot that contains a single point of color of a larger image.
Image - A type of data used for graphics or pictures.
metadata - is data that describes other data. For example, a digital image may include metadata that describe the size of the image, number of colors, or resolution.
WORK O' THE DAY:
►Let's make sure EVERYONE has had an opportunity to register for this class: AP class site
- Last day for AP Test signup's is November 8th. Basic info is HERE
- You can pay the bookkeeper directly or go online the school website
- You can apply to the AP for a reduced price test if you are on free/reduced lunch-- check with the bookkeeper for details.
═══════════════════════════
What is data compression as it relates to video and/or image files? Brainstorm some ideas with your group and come back here when you are finished....
Let's discuss...
Let's take a quick look at Khan Academy has to say about file compression
When do you suppose that it would be beneficial to compress a file by actually throwing away some of the data in the file?
Here's an (accurate? inaccurate? bogus? awesome?) description of LOSSY compression:
One example of lossy compression occurs when compressing certain image files. An algorithm evaluates pixels in the image. Images that are close enough (as determined by the algorithm) in color, are replaced by a SINGLE color. That entire section of the picture can be marked for compression.
Does that seem reasonable? Why or why not?
Does anyone know anything about the different image types: Gif, jpg, png???
Now let's have some fun with THIS widget courtesy of Code.Org Who can make the most successful compression algorithm?
═══════════════════════════
Please do a wee bit of research on the history of PKzip and jpg compression algorithms and be prepared to share your findings on Tuesday