The EXI instrument is a multi-wavelength radiation tolerant camera, EXI is capable of taking 12-megapixel images while maintaining the radiometric calibration needed for detailed scientific analysis. The instrument is being developed jointly by the Laboratory for Atmospheric and Space Physics (LASP) and Mohammed Bin Rashid Space Centre (MBRSC). The flexible readout modes allow customization of resolution, regions of interest and frame rate to meet the needs of the user and available memory and bandwidth. The lens system is a double lens assembly with a separate UV and VIS optical paths. The type of lens used is a double Gauss variant, a compound type lens used to provide low distortion high resolution imaging of Mars. The low focal ratio makes it possible to use very short exposure times to capture stable images during periapsis, while fitting both lens systems into a compact package. The image sensor is a 12-megapixel 12-bit monochrome CMOS array 4:3 imager. On-chip binning and region of interest windowing of the pixel array can be used to tailor image size and resolution as needed, minimizing the data rate. At full resolution, the sensor is capable of capturing 180 frames per second, enabling the possibility of 4K movie mode if desired. The use of discrete filters gives improved resolution in each colour compared with that using an RGB Bayer array. In addition, it provides more precise instrumental characterization, i.e., lower radiometric uncertainty of scientific imaging (needed for high accuracy retrievals of cloud optical depth). For the UV lens system, short-wavelength UV-C (245 – 275 nm) and long-wavelength UV-A (305 – 335 nm) will be cover ed. As for the VIS lens system, it will cover the bands; Red (625 – 645 nm), Green (506 - 586 nm) and Blue (405 – 469 nm).