A light-to-digital converter, comprising: a light-to-current converter; a current integrator with an integrator output resettable to a baseline level; a counter with a digital output; a comparator configured to compare said integrator output with a reference level corresponding to said baseline level, wherein an output of said comparator is connected to said counter; and a control unit controlling said counter and configured to: switch said light-to-current converter into being connected as a positive integration input to said current integrator, for, during a light-collecting phase, integrating a current from said light-to-current converter, said integrator output starting from said baseline value and ending at a value to be digitized, and switch a reference current source into being connected as a negative integration input to said current integrator, for, during a counting phase subsequent to said light-collecting phase, integrating a reference current from said reference current source, said integrator output starting from said value to be digitized and ending at said baseline value, the time spent integrating said reference current corresponding to said value to be digitized, wherein said counter is configured for measuring said time. a light-to-current converter; a current integrator with an integrator output resettable to a baseline level; a counter with a digital output; a comparator configured to compare said integrator output with a reference level corresponding to said baseline level, wherein an output of said comparator is connected to said counter; and a control unit controlling said counter and configured to: switch said light-to-current converter into being connected as a positive integration input to said current integrator, for, during a light-collecting phase, integrating a current from said light-to-current converter, said integrator output starting from said baseline value and ending at a value to be digitized, and switch a reference current source into being connected as a negative integration input to said current integrator, for, during a counting phase subsequent to said light-collecting phase, integrating a reference current from said reference current source, said integrator output starting from said value to be digitized and ending at said baseline value, the time spent integrating said reference current corresponding to said value to be digitized, wherein said counter is configured for measuring said time. switch said light-to-current converter into being connected as a positive integration input to said current integrator, for, during a light-collecting phase, integrating a current from said light-to-current converter, said integrator output starting from said baseline value and ending at a value to be digitized, and switch a reference current source into being connected as a negative integration input to said current integrator, for, during a counting phase subsequent to said light-collecting phase, integrating a reference current from said reference current source, said integrator output starting from said value to be digitized and ending at said baseline value, the time spent integrating said reference current corresponding to said value to be digitized,