There are lots of explanation about photodiode, light, light intensity, and digital ambient light are presented in this datasheet. The datasheet contains explanation around light sensor, threshold, range, and enhanced sensitivity.
In this datasheet you can find info about sensitivity, response, sensor, and ambient light. Below are excerpted from the datasheet:
Low-Power Digital Ambient Light Sensor with Enhanced Sensitivity Features The MAX44007 ambient light sensor features an I2C S Wide 0.025 Lux to 104,448 Lux Range digital output that is ideal for a number of portable applications such as smartphones, notebooks, and industrial sensors. At less than 1µA operating current, it is the lowest power ambient light sensor in the industry and features an ultra-wide 22-bit dynamic range from 0.025 lux to 104,448 lux. S Small, 2mm x 2mm x 0.6mm UTDFN-Opto Low-light operation allows easy operation in dark glass applications. The on-chip photodiode’s spectral response is optimized to mimic the human eye’s perception of ambient light and incorporates IR and UV blocking capability
Giving more content, this datasheet gives us information things like configuration, ambient light sensor, photodiode current, and ambient.