THD204 - THD204 TMA01 Part (1)
a) Displaying a bitmap on the monitor screen
The colour information for each pixel is stored in memory (bitmap) this is sent to the PC video card.
The video card performs digital to analogue conversion of the binary data (bitmap) into electrical signals, one each for red, green and blue. These signals are proportional to the original binary values. The video card then creates four analogue signals, three of the signals being red, green and blue and the fourth for synchronisation. The synchronisation signal is used for timing; this is to ensure that the monitor sweeps the three narrow electron beams synchronously across and down (raster scan) the monitor screen.
The monitor screen has extremely small triads of red, green and blue phosphor dots arranged across its surface to represent each pixel. The relative brightness of the red, green and blue signals determines how bright the dots will be, hence the perceived colour. To prevent the coloured beams illuminating more than one triad at a time a shadow mask is employed between the electron guns and the phosphor screen.
b) Factors limiting the perceived quality on the screen
- a) Capture resolution - if the number of pixels per inch also known as dots per inch (DPI)is too low then picture quality will suffer. Curved lines on the image will appear to have jagged edges. Use a higher resolution when capturing the image to cure this one.
- b) Not enough memory - shouldn't be a problem on a modern PC but may affect an older one. Bitmap files can be extremely large if working at high resolution, so you may have to lower the resolution for best results.
- c) Monitor/video card compatibility - are they capable of the resolution required.
Part (1b)
Convergence
The concept of convergence for this course is the way in which computers and digital communications have converged to produce Information Technology. Computer and digital communications have also been subject to convergence themselves for us to reach this point i.e. the computer and the modem when linked people we able to sent data electronically. This convergence was primarily moved by the digital representation of information and the need to transmit/edit/manipulate etc. data. Convergence in this case is basically the ability to transfer data from one medium to another or from system to system.
Description of Product
For this I have chosen the "fax - machine". The fax machine has been enable by the convergence of microprocessor, modem, photocopier and printing technologies.
The page(s) to be sent are loaded into the input area of the photocopier, the operator then uses the onboard keypad to dial the number for the remote machine. On connection and after a short modem preamble the sheets to be copied are drawn under microprocessor control through the photocopy stage, which converts the information to digital picture format. The microprocessor each machine controls the actions of that machine.
The digital data is passed to the modem where it is modulated for onward transmission to the remote modem via the telephone line. On receiving the modulated data the remote modem demodulates the digital information. The digital information is passed to the printer assembly, which prints copies of the original pages. This has been a very brief description of a fax machine.
Description of advantages
- a) No typing required (Original documents can be sent).
b) Easy of use.
c) Faster then snail mail.
d) Pictorial information can be sent i.e. map details
e) Can be used as a black and white photocopier ( some models )
Description of disadvantages
- a) Relatively slow transmission speeds, typically 14.4kbs.
b) Easy to dial wrong numbers and send your documents anywhere.
c) No good for colour.
Explicit use of design issues
- a) Speed - much faster than TELEX (text only) and able to transmit graphics.
b) Capacity and Costs - allows greater transmission and reception speeds typically 14.4kbs compared with TELEX which I believe was 75 baud max. <Wednesday, 11 July, 2007 18:13hines will talk to each other.
d) Reliability - far more reliable than the old TELEX.