The simulation pipeline in ISET begins with scene data ; these are transformed by the imaging optics into the optical image, an irradiance distribution at the image sensor array; the irradiance is transformed into an image sensor array response; and the image sensor array data are processed into an image for display.

The scene information is modeled as light from a diffusely reflecting plane at a fixed distance from the imaging lens. Equivalently, you can imagine the scene as a diffusely emitting surface at that distance.

The ISET Digital Camera Simulator includes a database of High Dynamic Range Spectral (HDRS) Scenes, as well as tools to create physically accurate models for a variety of different imaging conditions.  The HDRS scene database is created using methods that ImagEval developed to acquire estimates of the spectral irradiance (photons/sec/nm/m²) generated in both high and low dynamic range imaging environments.  Spectral irradiance images are acquired using a high-resolution scientific-grade color camera combined with calibrated color filters.  The environment is further calibrated using high quality standard reflectance sources (LabSphere Spectralon SRM-99) and a spectro-radiometer (PhotoResearch PR-650).

The high quality of HDRS scene data serves as a source of input data to the simulator.  From these images, the performance of cameras with lower resolution and lower quality optics can be modeled by adding different types of sensor noise and optical distortion to the acquired image data set.