A standard technique to make the faint regions more obvious is to use pseudo-colour . This image is burnt out in just the same way as the previous one. A solution is the Logarithmic grey-scale . Having gone this far, we might as well complete the process by applying pseudo-colour as well. OK, we admit it, this is mainly to make the images look more exciting, although it does improve the contrast of fine details a bit.
Every image is imperfect in two or three different respects.
This is measured by the size of the pattern produced by the spread-out light from a single point, called the beam in radio astronomy and the Point Spread Function in most other applications. True zero is rendered dark blue. The stippling due to noise is clearest where the sky is really completely dark, so that only the noise contributes to the image. If we use a smaller beam, we are looking at a smaller region of sky for each measurement, and so we receive a smaller amount of power, hence the noise is relatively larger. A familiar example is the various lens flare effects produced by a camera pointing too close to the Sun.