Despina,

a) does dynamic range 1000:1 same as 1 order of magnitude?

1 OoM is like shifting the decimal point to the left/right by one digit

(divide/multiply by 10), so 1000:1 = 3 OoM

b) what is maximum dynamic range that can exist in real world?

Very much depends on your scene: The sun has a luminance of 10^9 cd/m2,

and 'no light at all' would be 0 cd/m2.

c) what dynamic range can human eye see?

Please see WebHDR:

http://luminance.londonmet.ac.uk/webhdr/

d) what do we mean with cd/(m^2) ? where m^2: m=base, 2 = exponent

candela per meter square is the unit of luminance. 2 is not an exponent,

just a simple square.

See SynthLight, chapter one for more info on photometric units:

http://www.learn.londonmet.ac.uk/packages/synthlight/handbook/index.html

Axel