Which colours can you see in the photographs?
The colours that I see in the photographs are : green, white and pink.
1) The first-person personal pronoun " I " is always capitalized in English.
2) The sentence is complete only with a period ( . ) or an exclamation mark ( ! ) (A question mark ( ? ) can also end a sentence, but here it does not make sense.
And one suggestion to improve the style.
The sentence flows more smoothly if we leave out the colon ( : ) and say simply, ".....in the photograph are green, white and pink.
Thank you so much.