Patent ID: 6886902

Claim:
An ink jet printing system ( 10 ) comprising: printing equipment ( 12 ) having a ink jet printhead ( 22 ) for printing on a medium via the ejection of droplets of ink; a print driver ( 21 ) associated with said printing equipment ( 12 ) and configured both for processing data to be printed on the basis of information indicative of the medium and of the dimensions of the droplets of ink on the medium and for supplying the processed information to the printing equipment ( 12 ); pattern printing means for printing on said medium with said ink jet printhead ( 22 ) a plurality of patterns ( 30 , 30 a, 30 b, 30 c ) of predefined different densities (K s ), in order to obtain corresponding optical effects; superpixel printing means for printing on said medium with said ink jet printhead ( 22 ) an area constituted by at least one typical superpixel ( 31 ) having a predefined intensity and being calculated from typical information on the medium and on the printed dot size; optical analysis means comprising an optical device ( 24 ) associated with said printing equipment ( 12 ), said optical analysis means being configured for: reading by said optical device ( 24 ) such plurality of printed patterns ( 30 , 30 a, 30 b, 30 c ), analyzing the optical signals (V A ) generated by said optical device ( 24 ) by reading said plurality of printed patterns ( 30 , 30 a, 30 b, 30 c ), extrapolating from the analysis of said optical signals corresponding to said printed patterns ( 30 , 30 a, 30 b, 30 c ) a characteristic curve indicative of the optical effect of said printed patterns upon changes in the density of said printed patterns ( 30 , 30 a, 30 b, 30 c ), reading by said optical device ( 24 ) such printed typical superpixel ( 31 ), and identifying a real optical density (K t ) corresponding to said printed typical superpixel ( 31 ), by interpolation of said characteristic curve with the optical signal generated by said optical device ( 24 ) by reading said printed typical superpixel ( 31 ); computing means ( 14 ) for calculating the real dimensions (A d ) of the dot printed on the medium by said real optical density (K t ) identified by said optical analysis means; and means for supplying said print driver ( 21 ) with said real dimensions (A d ) of the dot printed on the medium.