An image sensor comprising a matrix of pixel rows and columns, each pixel having a photodiode and a node for storing charges in order to collect, at the end of a charge integration period, the charges accumulated in the photodiode, the photodiodes being produced in an active semiconductor layer of a first type of conductivity and comprising a diffusion of a second type of conductivity covered by a surface layer of the first type connected to a reference potential of the active layer and the matrix being organized in groups of at least two adjacent pixels, with means for grouping in one pixel the charges generated in the two pixels, comprising at least one charge storage gate (G21) arranged between the photodiode (PD1) of the first pixel and the photodiode (PD2) of the second pixel, the temporary storage gate being disposed above an active layer portion of the first type and dissymmetrically set up between an upstream and a downstream side, being: - on the upstream side, adjacent to the photodiode (PD1) of the first pixel by the end of at least one narrow finger (DGT) extending towards this photodiode (PD1), - on the downstream side, adjacent to the photodiode (PD2) of the second pixel by a dimension wider than the narrow finger, - and, with the exception of the end of the narrow finger, separated from the photodiode of the first pixel by a doped insulation region of the first type of conductivity, which is more doped than the surface regions of the photodiodes, and is brought, as item, to the potential of the active layer and means being provided for applying to the temporary storage gate a succession of potentials that are: - a low potential prohibiting the passage of charges between the photodiode (PD1) of the first pixel and the photodiode (PD2) of the second pixel during the charge integration period, - then a high potential temporary storage control signal permitting the discharge of the charges accumulated in the photodiode (PD1) of the first pixel and the photodiode (PD2) of the second pixel under the temporary storage gate, then a low potential allowing the discharge of the charges on the intermediate storage gate toward the photodiode (PD2) of the second pixel only. - on the upstream side, adjacent to the photodiode (PD1) of the first pixel by the end of at least one narrow finger (DGT) extending towards this photodiode (PD1), - on the downstream side, adjacent to the photodiode (PD2) of the second pixel by a dimension wider than the narrow finger, - and, with the exception of the end of the narrow finger, separated from the photodiode of the first pixel by a doped insulation region of the first type of conductivity, which is more doped than the surface regions of the photodiodes, and is brought, as item, to the potential of the active layer - a low potential prohibiting the passage of charges between the photodiode (PD1) of the first pixel and the photodiode (PD2) of the second pixel during the charge integration period, - then a high potential temporary storage control signal permitting the discharge of the charges accumulated in the photodiode (PD1) of the first pixel and the photodiode (PD2) of the second pixel under the temporary storage gate, <EOS>