Abstract: In a scanning system converting system for a display unit, a decoder decodes a coded image data to output a decoded image data and a control data. The coded image data is obtained by coding a first image data, and the control data indicates whether a scanning system of the first image data is a progressive scanning system or an interlace scanning system and whether fields of the first image data are correlated. A control section selectively generates the effective indication signal and first and second control signals based on the control data supplied from the decoder. A converting section selectively outputs, as a second image data, one of a current field of the decoded image data, a previous field of the decoded image data and an interpolated image data for every line based on the first and second control signals supplied from the control section.