I saw a picture on google which I would like to take. I won't copy him 100%. I loved that idea
In general, copyright covers specific expression of an idea, not the idea itself. Also, while law does vary by jurisdiction, international treaties make this aspect, at least, fairly consistent.
However, note that in practice, this covers a lot more than you might think. Note that for example specific, distinctive characters can fall under copyright, so, for example, you can't say "Oh, I'm just using the idea of Harry Potter in a story." An analogy might apply in a visual-arts case. If the photo idea you are copying has distinct creative elements which your copy also expresses, copyright could... come into the picture. (Pun inevitable. Sorry.)
This isn't just theoretical: consider the case of the red bus on the Westminster bridge: here, a tea company used a selective-color photograph of a red bus on a black & white background, and they were successfully sued by a souvenir company which sold a similar photograph:
Read more about this on this law blog;
Many photographers (and lawyers!) feel a little uncomfortable with this precedent, but one key thing is that intention matters:
The judge noted that “the whole point of this case is that [the defendant wants] lawfully to produce an image which does bear some resemblance to the claimant’s work."
It's also worth noting that this is a commercial case. Copying what others do is an important means of learning, and it's probable that for most uses a fair use defense would apply. If you're copying the work and then using it in a way that competes with the original, probably not. (But note in any case that there's no a priori fair use under most copyright law; it's a defense you can use if you are sued.)
Personally, I hope that the judge in this case was not particularly aware that selective color like this isn't particularly creative or interesting (and is even provided as an automatic feature in many cameras). Without that awareness, it's easier to see this as a distinctive and unique composition with special artistic merit. If "used that camera mode on a distinctive object" is all it takes for copyright to be asserted... that's a pretty strong.
It is not inherently bad to copy an idea, though your actions could make it immoral.
When learning, especially studio lighting, it is commonplace to copy images to recreate scenes.
When shooting weddings, many brides will Pinterest a favorite photo or two and you won't get out alive without getting that shot.
All that being said, one should never try to pass off these ideas as their own. Always credit your inspiration.