A display system configured to receive input image data specified in a first color space and to output image data specified in a second color space, said display system comprising: a display panel comprising a subpixel repeating group with at least four primary colored subpixel that define said second color space; a pre-reduction module configured to generate reduced input image data values from the input image data values, said pre-reduction module comprising, for each color channel of the first color space: a plurality of right shift registers each configured to output an input image data value shifted by mutually different amounts at a shift register output; a plurality of adders each configured to add a shift register output from one of the right shift registers to a shift register output from another of the right shift registers to provide an adder output; and a multiplexer configured to receive as multiplexer input data (a) the shift register output from each of the plurality of right shift registers and (b) the adder output from each of the plurality of adders, the multiplexer further configured to receive pre-reduce register data that controls which one of the multiplexer input data is provided as multiplexer output data, wherein the multiplexer output data constitutes the reduced input image data; and a gamut mapping module configured to receive said reduced input image data values and to output to the display panel image data specified in the second color space. a display panel comprising a subpixel repeating group with at least four primary colored subpixel that define said second color space; a pre-reduction module configured to generate reduced input image data values from the input image data values, said pre-reduction module comprising, for each color channel of the first color space: a plurality of right shift registers each configured to output an input image data value shifted by mutually different amounts at a shift register output; a plurality of adders each configured to add a shift register output from one of the right shift registers to a shift register output from another of the right shift registers to provide an adder output; and a multiplexer configured to receive as multiplexer input data (a) the shift register output from each of the plurality of right shift registers and (b) the adder output from each of the plurality of adders, the multiplexer further configured to receive pre-reduce register data that controls which one of the multiplexer input data is provided as multiplexer output data, wherein the multiplexer output data constitutes the reduced input image a plurality of right shift registers each configured to output an input image data value shifted by mutually different amounts at a shift register output; a plurality of adders each configured to add a shift register output from one of the right shift registers to a shift register output from another of the right shift registers to provide an adder output; and a multiplexer configured to receive as multiplexer input data (a) the shift register output from each of the plurality of right shift registers and (b) the adder output from each of the plurality of adders, the multiplexer further configured to receive pre-reduce register data that controls which one of the multiplexer input data is provided as multiplexer output data, wherein the multiplexer output data constitutes the reduced input image data; and a gamut mapping module configured to receive said reduced input image data values and to output to the display panel image data specified in the second color space.