Genjutsu is measured by Intelligence.

[Megatolium]

Everything in a genjutsu need to be shaped and manipulated to a point it seem realistic, try imagining yourself kicking a man off a cliff, every detail such as grass, insects, water. Tough aint it?

That's why I think the more creative and intelligent you are the more powerful your genjutsu.

Like Kurenai example, she uses genjutsu to confuse and scare her enemies even though she don't have Sharingan.

Itachi is a good example too, his caliber with the Sharingan is so mastered he can make an 3-Tomoe Sharingan Genjutsu as strong as Tsukuyomi.

[LssJBroly]

Never thought about that >_O

[Madara55]

Yeah

[Dribbles]

You didn't really express it right, but what you're trying to say is that the more creative you are with your imagination and intelligence, the better you would be able to pull off a genjutsu.

Well it would defiantly be an adding factor, but it would still require immense skill and training to even pull one off, depending on what type of genjutsu used. But in the end yes, it would come down to how well you can think of the situation you're putting an enemy in to better a genjutsu.

[LssJBroly]

You didn't really express it right, but what you're trying to say is that the more creative you are with your imagination and intelligence, the better you would be able to pull off a genjutsu.

Well it would defiantly be an adding factor, but it would still require immense skill and training to even pull one off, depending on what type of genjutsu used. But in the end yes, it would come down to how well you can think of the situation you're putting an enemy in.

Okay this makes some sense as well

[Azearl]

yup.

[Kyuubibomb]

agree

[Délta]

nice well done

[Owarij]

Not only that, But you need to have intricate knowledge of how the human body works, and each cranial nerve that you're going to be controlling

[ShaneEyyy]

If you look at the data books. The ninja with the highest Genjutsu have 4-5/5 for Intelligence.

[Owarij]

The ninja with the highest Genjutsu have 4-5/5 for Intelligence.

? 5 is the highest,

Kurenai has 4.5 intelligence
Hiruzen has 5 intelligence
Itachi has 5 intelligence
Oro has 5 intelligence

all of these have 5 in genjutsu