Photogravure printing avoiding moire effects - using formula involving only whole numbers to determine size and angular position of grid mesh

摘要

The two whole numbers K and L, K being the greater, are chosen so that they satisfy the equation (K2+L2)/2(K-L)=M where M is also a whole number. The number (K) represents the base of a right angled triangle which has a hypotenuse equal to the side of one of the squares of the grid. The angle through which one grid is rotated with respect to the other is denoted by (P) and is defined by the equation P=arctan(K/L)-arctan(L/K) and lies between 58 and 62 deg. A first grid is formed with a grid position and size determined by K and L and a second grid is formed the same way but the adjacent and the opposite are swapped. A third grid has the opposite equal to the adjacent. USE/ADVANTAGE - Photogravure printing with reduction of moire effects to a min.