ContrastChart app for iPhone and iPad

Contrast Chart is an interactive number and letter contrast sensitivity test. With Contrast Chart, human visual contrast sensitivity can be evaluated quickly and easily.

Contrast sensitivity of the visual system refers to the ability to see low contrasts, i.e. small differences in brightness.

Good contrast sensitivity is particularly important in difficult viewing conditions, which can reduce the contrast of the scene. One may encounter such viewing conditions when driving in dense fog, heavy rain, in the glare of the lights of oncoming traffic at night, or in the glare of sunshine during the daytime, for example.

The app produces randomized sequences of number or letter images with decreasing contrast as shown in the screen shots. The number of possible character sequences is huge.