Image “quality”

High resolution alone does not promise good image or display quality. Contrast, noise and resolution are the three quantities for gauging image quality. The sharper the contrast (less blur), the higher the image quality. The lower the noise, the higher the image quality. The smaller the pixel size, the higher the resolution and therefore the higher the image quality. Sharp contrast alone, however, does not imply good image quality — we must still check the noise level and the resolution. By the same token, low noise, or high resolution, alone cannot make a good image. For an image to be of high quality, we need a combination of all three factors: sharp contrast and low noise and high resolution. The implications of contrast, noise and resolution of medical images are not whether the pictures look nice or not. They may cause artefacts or misrepresentations suggesting features which are in fact absent in the body of the person scanned. They may also cause important features not to be visible. This would lead to wrong diagnosis.