ImageRotate

ImageRotate[image] rotates image by 90° about its center.

ImageRotate[image, θ] rotates image by θ radians.

Examples

Rotate 90 degrees:

img = ExampleData[{"TestImage", "Lena"}];
ImageRotate[img]

Rotate by 45 degrees:

ImageRotate[img, Pi/4]

Please visit the official Wolfram Language Reference for more details.