How to block Google Images while allowing Google?
2014-02
It's harder and harder to block Google Images while allowing Google as their respective URLs have become very similar.
Still, is there any way to achieve it today ?
If you are interested in blocking Google Images because of seeing objectionable content you can consider looking into Covenant Eyes. With this paid service you can not only restrict which websites one can view but see a list of every site visited and I believe you can specify hours web viewing is accessible.
I have saw the sidebar marked in the picture enabled in other people. How can I enable this for me?
EDIT: The bar doesn't appear at all, I mean, the "-" sign of the show/hide options doesn't appear. How can I make show this?
See the little "-" sign in the top part of the circle in your screenshot? When you do a Google search, it'll be a "+" when the results are first returned. Click the + and it expands to the side bar you're talking about.
Click "Web [+] Show options..."
If that doesn't work, switch locals to en-US or en-GB (If you prefer English...)
Press the "Show Options" button in the left corner.
Google have a habit of gradually rolling out features to different locations. If you aren't seeing show or hide on the results page then Google probably haven't decided to give you that feature.
I found the answer.
You need to go to the option Interface Language and set it to English.