1. A method comprising: determining whether there is a partial change of screen that affects less than all of a display screen; building a histogram based on maximum difference of pixels versus their neighbors; performing a spatial analysis of the partial screen change to decide if the partial screen is a gradient image that involves first color change values smaller than second color change values, including determining if a screen change is a gradient image depending on whether a majority of maximum differences in color values being smaller falling into lower histogram bins; and if so, disabling phase-in of the screen change and if the spatial analysis indicates that the partial screen involves the second color change values larger than said first color change values, enabling phase-in of the screen change.