After we went over bitmaps there was just enough time to finish vector graphics and therefor finish of the data representation topic.
Have a look at wikipedia’s take on vector graphics as well as the SQA’s.
Category Archives: 1. Computer Systems
Image sizes
There are plenty of posts on the internet about image file sizes and image file types.
We discussed in class how to calculate image file sizes, however, it’s often hard for raw numbers to mean anything. We forget that file storage was not always the multi Gigabyte size it is now. Here is a way for you to try and get your head around it.
The new iPhone 4s’ camera has a resolution of 3264 by 2448 pixels @ 24 bits per pixel, how many uncompressed images can you fit on a standard 16GB iPhone 4s?
Homework for Thursday 1st Dec
Answer the following questions.
Convert the following to decimal
- 11111100 (2’s comp)
- 00110110
- 11111111 (2’s comp)
How many pixels in the following files
- 320×240 @ 8 bits/pixel
- 1024×768 @ 16 bit colour depth
- 1280×1024 @ 24bpp
What are the sizes of the following files in bytes
- 320×240 @ 8 bits/pixel
- 1024×768 @ 16 bit colour depth
- 1280×1024 @ 24bpp
Calculate the storage requirements for the following images in Megabytes (to 2 decimal places)
- 1440×1080 @ 24 bpp
- 1920×1080 @ 24 bpp
- 7689×4320 @ 24 bpp
Data representation – Arrangements
- Representation of positive numbers in binary including place values and range up to and including 32 bits
- Conversion from binary to decimal and vice versa
- Description of the representation of negative numbers using two’s complement using examples of up to 8 bit numbers
- Description of the relationship between the number of bits assigned to the mantissa/exponent and the range and precision of floating point numbers
- Conversion to and from bit, byte, Kilobyte, Megabyte, Gigabyte, Terabyte. (Kb, Mb, Gb, Tb)
- Description of Unicode and its advantages over ASCII
- Description of the bit map method of graphic representation using examples of colour/greyscale bit maps
- Description of the relationship of bit depth to the number of colours using examples up to and including 24 bit depth (true colour)
- Description of the vector graphics method of graphic representation
- Description of the relative advantages and disadvantages of bit mapped and vector graphics
- Description of the relationship between the bit depth and file size
- Explanation of the need for data compression using the storage of bit-map graphic files, as examples
Binary a review in slides
OK so here is what we have covered so far.
Data Representation Revision Notes
Here is the PDF of the paper copy I plan to hand out at the end of the topic.
These notes are short and to the point, think of them as like the how to pass book. Remember you should also be using Scholar.
Answers to yesterday’s homework
- 397 0000000110001101
- -45 11010011
- 128 10000000
- -120 10001000
- -13 11110011
- 0 00000000
- 1013 000000011110101
- -92 10100100
- -100 10011100
- -3 11111101
Binary 2’s Complement
I posted on this last year, I don’t feel the need to go back over it. However, if you would like me to give another full post please just ask.
Remember for 8 bit 2’s complement the column headers are -128 64 32 16 8 4 2 1
The homework for tonight is to convert the following to binary using 2’s complement, the answers should be in Bytes so either 8 or 16 bits.
- 397
- -45
- 128
- -120
- -13
- 0
- 1013
- -92
- -100
- -3
Have fun
2007 SQA Past Paper Marking Scheme
2007 Computing SQA Exam Intro
2007 Computing SQA Exam Section 1
2007 Computing SQA Exam Section 2 Intro
2007 Computing SQA Exam Q 17
2007 Computing SQA Exam Q 18
2007 Computing SQA Exam Q 19
Memory
Right by now you should deep in study and the difference between SRAM and DRAM may be giving you some grief. Have a look at this article.
Basically, SRAM is fast and expensive and DRAM is less expensive and slower. Now, there is a lot more to it than that so get out your notes and go look it up. P46 of the Scholar notes has this to say
SRAM chips are very fast but are not suited for very large amounts of memory. They are more suited to cache memory, where only small amounts are required. You will learn more about cache memory when we look at factors that affect system performance.DRAM chips are more widely used. They are much cheaper to produce, can hold larger amounts of data in a smaller physical area and require less power. They are dynamic, requiring a continuous signal to refresh the contents of the chip.
