1. A method of displaying strain image data for an imaged object, the method comprising: capturing strain image data for a plurality of image frames, said strain image data defining deformation of said object over an imaged region of said object; determining local image quality data for each of said image frames, said local image quality data comprising a measure of the quality of said strain image data varying over said imaged region for said each image frame; and displaying a representation of said strain image data for said imaged region of said object, using said local image quality data to provide a visual indication of the quality of said displayed representation varying over said imaged region or to improve a quality of said displayed representation of said strain image data.