Apparatus and method for transforming the digital representation of a color input image

A system for converting a first representation of a color input image to a second representation, the second representation being matched to a selected color coordinate system, the first and second representations comprising primary color components, the system comprising:

• a first plurality of primary conversion tables each converting between a primary color component of said first representation and color components of a third representation;
• a second plurality of overprint conversion tables for converting between an overprint color of said first representation and adjustment color components of said third representation;
• and
• summing means for summing the respective primary and adjustment color components outputs of said primary and overprint conversion tables thereby to produce color component values of said second digital representation.

A method for converting a first representation of a color input image to a second representation, the method comprising the steps of:

• mapping primary axes and overprint axes of a selected color coordinate system to primary axes and overprint axes of a printer color coordinate system of said second representation, thereby producing primary conversion tables and overprint conversion tables;
• and
• converting said first representation to said second representation utilizing said primary and overprint conversion tables,
• said step of mapping including the step of matching the color of a plurality of reference step wedges in said printer color coordinate system to the color of a small number of step wedges in said selected color coordinate system wherein said step wedges in said selected color coordinate system have color values along said primary and overprint axes of said selected color coordinate system.

A method for converting a first digital representation of a color input image to a second digital representation, the second digital representation being matched to a selected color coordinate system, the first and second digital representations comprising at least three color components, the method comprising the steps of:

• for each pixel in said input image,
• providing each of said color components of said first digital representation to respective primary conversion tables producing from each color component of said first digital representation a plurality of primary color components of a third digital representation;
• producing overprint values from at least two of said color components of said first digital representation and providing said overprint values to respective overprint conversion tables producing from each overprint value a plurality of adjustment color components of said third digital representation;
• and
• summing together the respective primary and adjustment color components of said third digital representation produced from said steps of providing and producing thereby to produce color component values of the second digital representation.