The invention aims at providing a bulk material cooler particularly for hot cement clinker, wherein the conveyance performance and the efficiency of the cooler are enhanced and problems due to wear are reduced. In an embodiment, one or more media assets are received. The local phase filter starts by dividing the data into a set of smaller sub-spaces. The filter has parameters which are derived from previously traversed pixel values of the image. A printing operation selecting unit uses a remaining area of an already-used ink area for formation of a next print image when the total number of pixels is smaller than the second threshold in every one of all the areas, and uses an ink area in a new unit area for formation of a next print image when the total number of pixels is equal to or larger than the second threshold. The polyurethane which is the reaction product of at least one polyol, at least one organic diisocyanate and at least one polyol chain extender contains one or more pentaerythritol diphosphites color stabilizers conforming to a specific formula exhibits improved color stability and improved processability.