A display device having a display panel with unit pixels, each made up of red, green, blue and white, RGBW, sub-pixels, wherein the display device comprises a conversion section that is adapted to convert RGB input data of bit width t to R'G'B'W data of bit width u with u < t, wherein the upper u bits of input RGB data are an integer part and the lower (t-u) bits are a decimal fraction part, the converted R'G'B'W data being sent to the display panel of the device for controlling light emission of each unit pixel based on the data, wherein the conversion section is adapted to: - receive RGB input data of bit width t; - calculate a minimum among the RGB input data; - obtain a white value W 0 by rounding the calculated minimum to the bit width u; - determine white value candidates W comprising the white value W 0 and further white values obtained by adding integers in a range of -[n/2] and +[n/2] to the white value W 0, wherein n = 2^(t-u), and wherein [n/2] is a value obtained by truncating after the decimal point; - define a usage rate M for white, wherein the usage rate M is given by a ratio obtained by dividing a first integer by a second integer, wherein the first integer and the second integer are relatively prime positive integers with the first integer smaller than the second integer; - calculate, for each W candidate, respective R'G'B' output data in accordance with the respective relations R' = [R-MW+0.5], G' = [G-MW+0.5] and B' = [B-MW+0.5], wherein the calculated R'G'B' data is rounded to the bit width u; - determine for each W candidate and the associated R'G'B' output data, respective rgb data indicative of the RGB component that can be obtained on basis of respectively converted R'G'B' data of bit with u in accordance with the respective relations r = (R'+MW), g = (G'+MW) and b = (B'+MW); - calculate, for each W candidate and the associated rgb data, a total of absolute values of errors by performing the weighted sum |α(R-r) + β(G-g) + γ(B-b)|, wherein α, β and γ represent weights; and - select those R'G'B'W output data of bit width u that minimize the total of absolute values of errors. - receive RGB input data of bit width t; - calculate a minimum among the RGB input data; - obtain a white value W 0 by rounding the calculated minimum to the bit width u; - determine white value candidates W comprising the white value W 0 and further white values obtained by adding integers in a range of -[n/2] and +[n/2] to the white value W 0, wherein n = 2^(t-u), and wherein [n/2] is a value obtained by truncating after the decimal point; - define a usage rate M for white, wherein the usage rate M is given by a ratio obtained by dividing a first integer by a second integer, wherein the first integer and the second integer are relatively prime positive integers with the first integer smaller than the second integer; - calculate, for each W candidate, respective R'G'B' output data in accordance with the respective relations R' = [R-MW+0.5], G' = [G-MW+0.5] and B' = [B-MW+0.5], wherein the calculated R'G'B' data is rounded to the bit width u; - determine for each W candidate and the associated R'G'B' output data, respective rgb data indicative of the RGB component that can be obtained on basis of respectively converted R'G'B' data of bit with u in accordance with the respective relations r = (R'+MW), g = (G'+MW) and b = (B'+MW); - calculate, for each W candidate and the associated rgb data, a total of absolute values of errors by performing the weighted sum |α(R-r) + β(G-g) + γ(B-b)|, wherein α, β and γ represent weights; and - select those R'G'B'W output data of bit width u that minimize the total of absolute values of errors.