Can you rotate an image?

How does one rotate an image? For example in Colors I want the Wood to be horizontal instead of diagonal.

Use the Position Texture Tool.
Right context click on the face > Texture > Position

Position Texture Tool — SketchUp Help

Hi Geo, this might be about how the materials browser shows the grain direction, i.e. a permanent change for the (thus a new) material, created from one that already exists, though in the wrong direction.

Ah … I think you’re right @Wo3Dan.
In which case @HOBBYARCHITECT, you can export the existing material image.
Right context click on the the material in the Materials Browser In-Model panel > Export texture image

Edit (rotate) the exported image in your favorite image editor and save with appropriate new name.
Then bring the material image back into SU … File > Import > Use as texture
Add it to one of your collections for future use.

Thank you very much.