A graphical user interface for converting high dynamic range video data applied as an input into low dynamic range video data comprising: a video player region for displaying a tone mapped output of a video frame, comprising: - a regional current video output section for displaying a video output resulting of HDR conversion of a current video frame by a region-based tone mapping operator, said region-based operator using a plurality of exposure regions defined by a plurality of anchor points, one anchor point per exposure region; - a global current video output section for displaying a video output resulting of HDR conversion of the same current video frame using global-based tone mapping operator, said global operator using a single global exposure region corresponding to a single anchor point; and - the regional and global video output sections (12, 14) each comprising a respective video section and a respective histogram region, characterized in that - the histogram region in the regional output section is configured to display histogram intensity values for the current video frame and the plurality of anchor points operated by the region operator to show a division of the histogram into the plurality of exposure regions; - the global histogram region is configured to display the histogram intensity values for the current frame of video in the single global exposure region operated by the global operator; and - a regional control section having one regional changeable exposure control and one regional changeable contrast control for each one of the plurality of exposure regions, each operable for changing exposure and/or contrast parameters in the respective exposure region operated by said region-based operator; and - a global control section having a global changeable exposure control and a global changeable contrast control, operable to change contrast and/or exposure parameters in all of the exposure regions at the same time; wherein the regional current video output section, the global current video output section, and the control sections are presented simultaneously on a screen, and the video sections of the regional current video output section and global current video section are presented side by side on said screen, and said graphical user interface enabling concurrently displaying in said video sections disposed side by side, the current video outputs from respectively the region-based operator and the global operator, operating on a same input video frame based on locations of anchor points in the histogram region of the respective regional and video output sections and current control parameters including current regional and global contrast and exposure parameters in the respective regional and global control sections. - a regional current video output section for displaying a video output resulting of HDR conversion of a current video frame by a region-based tone mapping operator, said region-based operator using a plurality of exposure regions defined by a plurality of anchor points, one anchor point per exposure region; - a global current video output section for displaying a video output resulting of HDR conversion of the same current video frame using global-based tone mapping operator, said global operator using a single global exposure region corresponding to a single anchor point; and - the regional and global video output sections (12, 14) each comprising a respective video section and a respective histogram region, - the histogram region in the regional output section is configured to display histogram intensity values for the current video frame and the plurality of anchor points operated by the region operator to show a division of the histogram into the plurality of exposure regions; - the global histogram region is configured to display the histogram intensity values for the current frame of video in the single global exposure region operated by the global operator; and - a regional control section having one regional changeable exposure control and one regional changeable contrast control for each one of the plurality of exposure regions, each operable for changing exposure and/or contrast parameters in the respective exposure region operated by said region-based operator; and - a global control section having a global changeable exposure control and a global changeable contrast control, operable to change contrast and/or exposure parameters in all of the exposure regions at the same time;