Formal:
* Que bela fotografia! (pronounced: kay BEH-lah foh-toh-grah-FEE-ah) - This is the most literal translation and is appropriate for formal situations.
* Que linda fotografia! (pronounced: kay LEEN-dah foh-toh-grah-FEE-ah) - Similar to the first option, but uses a slightly more affectionate word for "beautiful".
Informal:
* Que foto bonita! (pronounced: kay FO-toh boh-NEE-tah) - A very common and natural way to say it.
* Que foto legal! (pronounced: kay FO-toh leh-GAHL) - Meaning "cool picture", this is a casual and friendly option.
* Que foto bacana! (pronounced: kay FO-toh bah-kah-NAH) - Similar to "legal", this also means "cool" or "awesome".
Adding a compliment:
* Que fotografia linda, adorei! (pronounced: kay foh-toh-grah-FEE-ah LEEN-dah, ah-doh-REY) - "What a beautiful picture, I loved it!"
* Que foto bacana, você tirou? (pronounced: kay FO-toh bah-kah-NAH, vo-seh tee-ROU?) - "What a cool picture, did you take it?"
Remember to adjust your choice based on the situation and your relationship with the person you are speaking to.