I stopped because I feel that I do not think anymore because starting level 4 (or 3), I browse the net for some tips and hints.
Try it, and goodluck thinking. :D
Okay, here are some hints from level one to five.
Level 1: Lower the brightness and max (I think) the contrast of the image. If you want, also zoom it. You will see a cute word in the trees. See it? Cute isn't it? :D
Level 2: Save the image, then go to properties, and look for the comment. Type it in your cellphone just like texting.
Level 3: Find the missing horoscope sign in the dominos, and arrange that word to create a new word. I think you can use anagram solver for finding the right word.
Level 4: Mercedes + Vin Diesel = ?. I don't think They have a relationship to each other, but think of a movie where Vin Diesel is the main actor. That movie is also the same to that prohibited for minors.
Level 5: Save the image, properties and then look for the comment. You will see, "split it here", cut those "it"s there and you will form that word. I think, it is a circle with a volume and area.
Level 6: I stopped here, so no hints for this level and above.