► We present a methodology to remove atmospheric effects from HiRISE images. ► We study the time evolution of the albedo of dark spots observed in Richardson Crater, on Mars south polar region. ► Our results support the gas venting hypothesis previously proposed to explain the formation of dark spots. ► We propose that, once dark spots form, liquid brine formation can temporarily drive their evolution. We present a methodology to remove atmospheric effects from High Resolution Imaging Science Experiment data in order to calculate the albedo of the martian surface in the near infrared (0.8–1μm), red (0.55–0.85μm), and blue green (0.4–0.6μm) spectral bands. The application of our methodology results in corrections of up to 20% in the albedo measured by the satellite. Time evolution of the surface albedo is used to study dark spots observed in Richardson Crater, on Mars south polar region. These dark spots form in late winter and vanish in late spring. They are of high scientific interest because they appear to be caused by the flow of granular material, liquid, or a combination of both. Besides images, the following data are used as ancillary information in our study: dust optical depth derived from measurements by the Thermal Emission Imaging System, the detection of the presence of either CO2 ice or H2O ice by the Compact Reconnaissance Imaging Spectrometers for Mars, surface pressure and temperature values derived from measurements by the Thermal Emission Spectrometer, and finally kinetic calculations and numerical modeling. Our results support the gas venting hypothesis previously proposed to explain the formation of dark spots. We show that the ejection of CO2 gas and accompanying loose material through cracks in the translucent CO2 ice layer, suggested by this hypothesis, is consistent with the time evolution of the surface albedo. Once dark spots form, surface albedo values indicate that they have three distinct areas: a dark core at their center, a brighter zone surrounding them (referred to as bright halo by various authors), and an optically distinct intermediate area separating the dark core from the bright halo. Our analysis indicates that these three areas are physically distinct and that the deposition and sublimation of CO2 and H2O ices are necessary to explain the time evolution of the albedo of the dark spots and the areas surrounding them. However, these conventional mechanisms cannot explain some observed features such as an unexpected decrease and subsequent increase in albedo while the surface temperature raises continuously. We hypothesize that this unexpected decrease in albedo is caused by brine formation and propose a mechanism to explain it. A new ejection of dark material or dust deposition could also explain this decrease. However, we show that these processes are unlikely to be the cause of the albedo decrease. The hypothesis that the dark spots observed in Richardson Crater contain liquid brines can be tested with laboratory experiments or in situ measurements by future landers.