No need to go for the warranty right now. You have to check for some steps:
1- Copy this photo to the PC and see if the picture is the same?
2- If Yes then the file might be corrupt due to bad sdcard. Use a dick checker (disk doctor) tool on the PC to check for the sdcard.
3- If No, it means the file is OK but it does not display correctly on your phone. It might be software (gallery) error or something else. Try to use another image view app (e.g ES File Explorer) to open the file and see if the problem still persist?
now, i take photos on internal memory, and i wait to see wath is happen.