In Odoo, images are uploaded to the image_1920 field, designed for high-resolution images, but the system generates smaller versions (e.g., image_512, image_256, image_128) for different contexts. 

Upload a high-quality image (e.g., 1024x1024 or 1920x1920) as you normally would by clicking on the edit icon on the image, and Odoo will handle resizing automatically.