A method of transmitting image data in an image display system, includes dividing the image data into framebuffers, and for each framebuffer: dividing the framebuffer into a number of vertical stripes, each stripe including one or more scanlines, dividing each vertical stripe into at least a first and a second block, each of the first and the second block comprising pixel data to be displayed in an area of the image, and storing first pixel data in the first block with a first resolution and second pixel data in the second block having a second resolution which is lower than the first resolution, transmitting the framebuffer over the digital display interface to a decoder unit, and unpacking the framebuffer, including upscaling the pixel data in the second block to compensate for the lower second resolution and optionally upscaling the pixel data in the first block.