Modified Use of the Subtractive Color Triangle to Obtain Mask Percentages

One of the more important uses of the subtractive color triangle as proposed by F. Preucil (1960) is to find mask percentages based on ratios of ink densities. Actually, this is not a solution to the general masking or color-mixture equations, and only serves as an approximation to the mask percentages of the two most important masks used in practice. However, without any further complication to the diagram an exact solution to the masking equations can be obtained (six masks) by merely modifying the procedure. A general proof is provided.