1. Make sure the photo has an alpha channel.
Right click on the photo layer in the layers dialogue and click on Add Alpha Channel
2, Select the Ellipse Select Tool
In the Tool Options check Fixed Aspect Ratio and (1:1) for a circle.
If required, check Expand From Centre
3. Create your selection on the required portion of the photo
4. Select > Invert
5. Edit > Clear (or press the Delete key)
The outside portion becomes transparent, in Gimp represented by a chequer board pattern
6. SAVE as a .xcf file. EXPORT as a .png (jpg does not support transparency)
Right click on the photo layer in the layers dialogue and click on Add Alpha Channel
2, Select the Ellipse Select Tool
In the Tool Options check Fixed Aspect Ratio and (1:1) for a circle.
If required, check Expand From Centre
3. Create your selection on the required portion of the photo
4. Select > Invert
5. Edit > Clear (or press the Delete key)
The outside portion becomes transparent, in Gimp represented by a chequer board pattern
6. SAVE as a .xcf file. EXPORT as a .png (jpg does not support transparency)