When an L*a*b* value of a certain color is outside a target color gamut to be converted, it is judged whether the L*a*b* value is located within the range of the color gamut set under a predetermined condition. A postal sorting installation including a sorting machine and a cart as described for assisting in transferring mailpieces. Each game unit is a game of chance or other game that does not rely primarily on the skill of the player.