To improve a picture’s resolution, increase its size, then make sure it has the optimal pixel density. The result is a larger image, but it may look less sharp than the original picture. The bigger you make an image, the more you’ll see a difference in sharpness.
What Sells Best On Shutterstock?
Some types of photos that sell best are Portrait Photography, Food Photography, Landscapes (usually with people) and fine art photography (artsy).