An integrated circuit for an imaging system is disclosed. In one aspect, an integrated circuit has an array of optical sensors, an array of optical filters integrated with the sensors and configured to pass a band of wavelengths onto one or more of the sensors, and read out circuitry to read out pixel values from the sensors to represent an image. Different ones of the optical filters are configured to have a different thickness, to pass different bands of wavelengths by means of interference, and to allow detection of a spectrum of wavelengths. The read out circuitry can enable multiple pixels under one optical filter to be read out in parallel. The thicknesses may vary non monotonically across the array. The read out, or later image processing, may involve selection or interpolation between wavelengths, to carry out spectral sampling or shifting, to compensate for thickness errors.