Uniformity of illumination
A perfect illuminator should light up a scene as evenly as possible. This is an important consideration when selecting the correct illumination product, and also when comparing products from different manufacturers.
Using homogeneous illumination will make the task of image analysis much easier and faster as it removes the need to normalise the lighting intensity in software. Some manufacturers provide distribution figures, often in the form of a graph, to show how their lights perform and to enable a reasoned choice between different illumination techniques.