Thank you very much for the reply. Apart from the changes you mentioned, I also did some other tweaks;
//desaturate
float middlegray=(res.r+res.g+res.b )*0.333;
float3 diffcolor=res.rgb-middlegray;
res.rgb-=diffcolor*0.4*tempF0;
Changed 0.333 to 0.100 and *0.4 to 0.1. It decreased the overall brightness a little bit more, and what's even more important for me, it made colors much more vivid; almost the same values with vanilla Morrowind. I don't know if it is because I use the default enbpalette, but ENB greatly faded the colours in my game. These tweaks more or less balanced that issue.
However, it is still too bright when you look into the sea, or into the sky, inside a forest: http://img210.imageshack.us/i/mgescreenshot9.jpg/
(It was taken a few steps before the final tweak, but the brightness is still the same in situations like this)
Maybe you'd like to see some comparisons of my colour tweak. Here, I took this pic as my base for comparison. It uses only MGE.
http://img401.imageshack.us/img401/412/mgescreenshot8.jpg
And my tweaks evolved as follows:
http://img267.imageshack.us/i/mgescreenshot14.jpg/
http://img210.imageshack.us/i/mgescreenshot13.jpg/
http://img180.imageshack.us/i/mgescreenshot11.jpg/
http://img402.imageshack.us/i/mgescreenshot12.jpg/
I hope this'll help anybody who is having colour problems like me.
Now, onto my next set of questions. Is there a manual which shows what each section, each line of "enbseries.ini" does? I'd be double-happy if there is another manual which explains the functions of the "effects.txt."
I also would like to learn how to make ENB bloom toggle-able. I'm sure ENB has an option for this, but I don't know how to utilize (or activate) the hotkeys.
Thanks in advance