1. An apparatus comprising one or more processors and at least one memory storing instructions that are executable by the one or more processors, the apparatus further comprising: an image data input device, implemented at least partially in hardware, that receives image metadata for a color-timing display and image data comprising pixel values; a pixel coordinate mapping device, implemented at least partially in hardware, that transforms the image data into transformed image data according to a parameterized transfer function characterized by a plurality of anchor points and a free parameter, the parameterized transfer function having a mid-range slope controlled by the free parameter, wherein transformations at the anchor points are not affected by the free parameter; wherein the anchor points comprise black level and white level anchor points and a mid-tone anchor point, the black level anchor point corresponding to a transformation from a black level of the color-timing display used in color-timing or approving the image data to a black level of a target display used for display of the transformed image data, the white level anchor point corresponding to a transformation from a white level of the color-timing display to a white level of the target display; wherein the mid-tone anchor point affects a target brightness of the image data on the target display; wherein the black level of the color-timing display differs from the black level of the target display and/or wherein the white level of the color-timing display differs from the white level of the target display; wherein at least one of the black level of the color-timing display or the white level of the color-timing display is a value specified by the image metadata; an image data output device, implemented at least partially in hardware, that outputs the transformed image data.