PC Graphics - From Megabytes To Modest Bytes. By Murray Niman G6JYB. The Problem. SIZE MATTERS ! How is it I can download a web page such as BBC News which may have 40 Images in a few seconds?
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ByMurray Niman G6JYB
SIZE MATTERS !
Also lots of others:-
Most of the ones we are concerned with are raw pixel data.
Do not confuse with WMF, PDF, Flash, smart shapes, Wordart etc
Powerpoint - combines any Pictures with text and graphics
Shockwave (SWF) & Flash - Vectored animation
A Pixel = A Picture Cell - one dot that is a colour
Everything is binary:
Note - a black/white photo is grey (RGB are all the same)
Colour uses RGB so needs upto three bytes instead of one
DPI - Dots per Inch (or pixels per inch)
An A4 page is ~12x8”
dpi Pixels Total Pixels
75 900x600 540,000
100 1200x800 960,000
150 1800x1200 2,160,000
200 2400x1600 3,840,000
300 3600x2400 8,640,000
600 7200x4800 34,560,000
1200 14400x9600 138,240,000
2400 28800x19200 552,960,000
- and remember is often 3bytes per pixel for full colour
This can give Big Gains . . .
A picture that is half the size is a quarter of the area/no of pixels
Need good quality originals:
GIF(16) as JPG: 73647!
3200 Colours in Use in Original
16 Colours in Use in GIF(16)