1. A method of printing an image on a printing medium with an inkjet printing device, the method comprising: providing data representative of an original image; calculating a total heat weighting value for the original image to indicate a degree of heat accumulation for the original image; comparing the total heat weighting value to R distinct reference values, R being an integer greater than or equal to one; selecting M image masks to be used to mask the original image, wherein a value of M is chosen according to comparison results between the total heat weighting value and the R reference values, M being an integer greater than or equal to one; masking the original image with the M image masks to produce M sub-images; and printing the M sub-images successively on the printing medium with a plurality of nozzles for superimposing the M sub-images on the printing medium, whereby the original image is printed on the printing medium.