Densitometer method and system for identifying and analyzing printed targets

Claim 3

The method of claim 1, characterized in that percent trap is calculated using the formula where T₂ is the largest measured optical density selected from the red, green or blue optical densities of the second down color; T₁ is the corresponding measured optical density of the first down color; and T is the corresponding measured optical density of the overprint.

Claim 4

The method of claim 2, characterized in that it further comprises the steps of determining, upon detection of an overprint, whether a red, green or blue overprint has been detected; and displaying the color overprint to the pressman.

Claim 5

The method of claim 2, characterized in that it further comprises the step of storing, upon measure­ment of an unprinted substrate, the red, green, blue and visual unprinted substrate optical densities as W r , W g , W b , W v , respectively.

Claim 6

The method of claim 4, characterized in that the percent dot area is calculated using the formula where D h is the largest measured halftone density, S      is the solid density corresponding to D h , and n      is the Yule-Nielsen factor.

Claim 7

The method of claim 1, characterized in that it further comprises the following step performed immediately after said measuring step: substracting corresponding stored substrate optical densities from said measured optical densities to obtain referenced optical densities which are used in all subsequent cal­culation and display steps.

Claim 8

A method for controlling a printing process comprising the steps of - measuring the red, green, blue an visual optical densities of a selected target; - comparing said measured optical densities to a first stored constant K1 to determine whether an unprinted substrate has been measured and, if so, dis­playing this fact to the pressman and repeating the above measuring step at a different target location; - where an unprinted substrate is not de­tected, comparing said measured optical densities to a second stored constant K2 to determine whether a solid black target has been read and, if so, storing the measured visual optical density as S v , displaying the fact to the pressman and repeating the above measuring step at a different target location; - where neither an unprinted substrate nor a solid black target is detected, comparing the measured red, green and blue optical densities to a third stored constant K3 and comparing the difference between the largest and smallest of the red, green and blue measured optical densities to a fourth stored constant K4 to determine whether an overprint has been measured and, if so, performing an overprint check as follows: comparing the measured green optical density to the measured red optical density and, where the green density is less that the red density, concluding that an overprint has been measured, where the measured green density is greater than or equal to the measured red density, comparing the measured blue optical density to the red density and, where the blue density is less than the red density, concluding that an overprint has been measured, where the measured blue optical density is greater than or equal to the red density, comparing the blue density to a fifth stored constant K5 such that, if the blue density is less than K5, it is con­cluded that a muddy solid magenta has been read, this fact is displayed to the pressman, the measured green optical density is stored as S g and the above measuring step is repeated, whereas if the blue density is greater than or equal to K5 it is concluded that an overprint has been measured; and where it is concluded that an overprint has been measured, the following additional steps are performed to determine and display percent trap: (i) storing the measured red, green and blue optical densities as overprint values T r , T g and T b , respectively; (ii) measuring the red, green, blue optical densities of the first down color and storing these values as T 1r , T 1g , T 1b m respectively; (iii) measuring the red, green and blue opti­cal densities of the second down color and storing the greatest measured value as T₂; (iv) calculating percent trap using the equation of claim 2 where T and T₁ are the overprint and first down color density values corresponding to the filter color designated as T₂; and (v) displaying the percent trap to the press­man,

Claim 9

whereupon the above measuring step is repeated on a different target location; where none of an unprinted substrate, a solid black, a muddy magenta or an overprint are detected, comparing the measured red, green and blue optical densities to a sixth stored constant K6 to determine whether a solid color target has been measured and, if so, storing the largest of the measured red, green or blue optical densi­ties as the corresponding solid density S r , S g , S b and repeating the above measuring step on a different target location; - where none of an unprinted substrate, a solid black, a muddy magenta, an overprint or a solid color are detected, comparing the difference between the largest and smallest measured red, green and blue optical densities to a seventh stored constant K7 such that, if the difference is less than K7 a black halftone is assumed and if the difference is greater than or equal to K7 a color halftone is assumed, whereupon per­cent dot area may be determined for the halftone using the equation of claim 5, the percent dot area being displayed to the pressman; controlling the printing process based upon the informa­tion generated and displayed in the foregoing steps.

Claim 10

The method of claim 7, characterized in that it further comprises the step of storing, when an un­printed substrate is detected, the red, green, blue and visual unprinted substrate optical densities as W r , W g , W b and W v , respectively.

Claim 11

The method of claim 7, characterized in that it further comprises the following step performed immediately after said measuring step: subtracting corresponding stored substrate optical densities from said measured optical densities to obtain referenced optical densities which are used in all subsequent calculations and displays.

Claim 12

A densitometer system for a printing process comprising - measuring means for measuring the red, green, blue and visual optical densities of a selected target; - first comparison means for determining, from said measured optical densities, whether an un­printed substrate is detected and, if so, displaying this fact to the pressman, whereupon said measuring means measures a different target; - second comparison means for determining, where an unprinted substrate is not detected, whether a solid black has been measured and, if so, displaying this fact to the pressman and storing the measured vi­sual optical density as the corresponding solid visual density, whereupon the said measuring means measures a different target; - third comparison means for determining, from said measured optical densities, where neither an unprinted substrate nor a solid black is detected, whether an overprint has been measured, whereupon (i) an overprint density value storage means stores the measured red, green and blue optical densities as T r , T g , T b , respectively; (ii) an overprint check means determines whether an overprint has been measured and separately measures and stores the first down color red, green and blue optical densities and the second down color red, green and blue optical densities; (iii) a percent trap means determines percent trap from said measured optical densities of said over­print and said first and second down colors, and (iv) a percent trap display means displays the percent trap to the pressman for use in controlling the printing process, whereafter said measuring means measures a different target;

Claim 13

A densitometer system for a printing process comprising - measuring means for measuring the red, green, blue and visual optical densities of a selected target; - first comparison means for determining, from said measured optical densities, whether an un­printed substrate is detected and, if so, displaying this fact to the pressman, whereupon said measuring means measures a different target; - second comparison means for determining, where an unprinted substrate is not detected, whether a solid black has been measured and, if so, displaying this fact to the pressman and storing the measured vi­sual optical density as the corresponding solid visual density, whereupon the said measuring means measures a different target; - third comparison means for determining, from said measured optical densities, where neither an unprinted substrate nor a solid black is detected, whether an overprint has been measured, whereupon (i) an overprint density value storage means stores the measured red, green and blue optical densities as T r , T g , T b , respectively; (ii) an overprint check means determines whether an overprint has been measured and separately measures and stores the first down color red, green and blue optical densities and the second down color red, green and blue optical densities; (iii) a percent trap means determines percent trap from said measured optical densities of said over­print and said first and second down colors, and (iv) a percent trap display means displays the percent trap to the pressman for use in controlling the printing process, whereafter said measuring means measures a different target;

Claim 14

- fourth comparison means for determining, where an unprinted substrate, a black solid or an over­print is not detected, whether a solid color has been measured, whereupon the greatest of the measured red, green or blue optical densities is stored by a solid density value storage means as the corresponding solid color density; and - percent dot area means for determining and displaying percent dot area where a halftone is detected, that is, where an unprinted substrate, a solid black, an overprint or a solid color target is not detected.

Claim 15

- fourth comparison means for determining, where an unprinted substrate, a black solid or an over­print is not detected, whether a solid color has been measured, whereupon the greatest of the measured red, green or blue optical densities is stored by a solid density value storage means as the corresponding solid color density; and - percent dot area means for determining and displaying percent dot area where a halftone is detected, that is, where an unprinted substrate, a solid black, an overprint or a solid color target is not detected.

Claim 16

The densitometer system of claim 10, cha­racterized in that said percent dot area means deter­mines percent dot area using the formula where D h is the largest measured halftone density, S is the solid density corresponding to D h , and n is the Yule-Nielsen factor, and displays either the calculated percent dot area or an error signal if no corresponding solid density value has been stored.

Claim 17

The system of claim 10 characterized in that said overprint check means also determined whether a red, green or blue overprint has been detected and said percent trap display means also displays the color overprint detected.

Claim 18

A densitometer system for a printing process comprising - measuring means for measuring the red, green blue and visual optical densities of a selected target; - first comparison means for comparing said measured optical densities to a first constant K1 to determine whether an unprinted substrate has been measured, and if so, displaying this fact to the press­ man, whereupon said measuring means measures a differ­ent target; - second comparison means for comparing, where an unprinted substrate is not detected, said measured optical densities to a second stored constant value K2 to determine whether a solid black target has been read, whereupon the measured visual optical density is stored as the corresponding solid density S v , the fact that a solid black target has been read is displayed to the pressman and said measuring means measures a different target; - third comparison means for comparing, where neither an unprinted substrate nor a solid black target is detected, the measured red, green and blue optical densities to a third stored constant K3 and for comparing the difference between the largest and smallest of the measured red, greenand blue optical densities to a fourth stored constant K4 to determine whether an overprint has been measured, whereupon an overprint check means performs an overprint check by comparing the measured green density to the measured red density and, if the green density is less than the red density, concluding that an overprint has been measured; where the green density is greater than or equal to the red density, comparing the blue density to the red density and, where the blue density is less than the red density, concluding that an overprint has been measured; where the blue density is greater than or equal to the red density, comparing the blue density to a fifth stored constant K5 such that, if the blue density is less than K5, it is concluded that a muddy solid magenta has been read, this fact is displayed to the pressman, the measured green optical density is stored as S g and said measuring means measures a differ­ent target; whereas, if the blue density is greater than or equal to K5, it is concluded that an overprint has been measured; and where it is concluded than an overprint has been measured, said overprint check means (i) stores the measured red, green and blue optical densities as overprint values T r , T g , T b , re­spectively; (ii) measures the red, green, blue optical densities of the first down color and stores these values as T 1r , T 1g and T 1b , respectively; (iii) measures the red, green and blue opti­cal densities of the second down color and stores the greatest measured value as T₂; (iv) calculates percent trap using the equa­tion of claim 2; (v) displays percent trap to the pressman for use in controlling the printing process, whereupon said measuring means measures a different target;

Claim 19

- fourth comparison means for comparing, where an unprinted substrate, a solid black, a muddy magenta or an overprint is not detected, the measured red, green and blue optical densities to a sixth stored constant K6 to determine whether a solid color target has been measured and, if so, storing the greatest measured optical density as the corresponding solid optical density, S r , S g or S b ; and - percent dot area means for comparing, where an unprinted substrate, a black solid, a muddy magenta, an overprint or a solid color is not detected, the difference between the largest and smallest of the measured red, green and blue optical densities to a seventh stored constant K7 such that, if the differ­ence is less than K7, a black halftone is assumed and, if the difference is greater than or equal to K7, a color halftone is assumed, whereupon said percent dot area means may determine percent dot area for the half­tone using the formula of claim 5, and said percent dot area means displaying either the calculated percent dot area to the pressman for use in controlling the printing process, or an error signal where no value has been stored for the corresponding solid density.

Claim 20

The system of claim 13, characterized in that it further comprises substrate density storage means for storing the red, green, blue and visual optical densities of an unprinted substrate.

Claim 21

The system of claim 13, characterized in that said measuring means subtracts corresponding stored substrate optical density values from said measured optical density values to obtain referenced densities used in all calculations and displays.

Claim 22

The system of claim 13, characterized in that said overprint check means also determines whether a red, green or blue overprint has been detected and displays the color overprint as well as percent trap to the pressman.

Claim 23

A densitometer system for a printing pro­cess comprising measuring means for measuring the red, green, blue and visual optical densities of a selected target; comparison means for determining from said measured optical densities whether an overprint has been measured, whereupon (i) an overprint density value storage means stores the measured red, green and blue optical densi­ties as T r , T g , T b , respectively; (ii) an overprint check means determines whether an overprint has been measured and separately measures and stores the first down color red, green and blue optical densities and the second down color red, green and blue optical densities; (iii) a percent trap means determines percent trap from said measured optical densities of said over­print and said first and second down colors; and (iv) a percent trap display means displays the percent trap to the pressman for use in controlling the printing process.

Claim 24

A densitometer system for a printing pro­cess comprising measuring means for measuring the red, green, blue and visual optical densities of a selected target; comparison means for determining from said measured optical densities whether an overprint has been measured, whereupon (i) an overprint density value storage means stores the measured red, green and blue optical densi­ties as T r , T g , T b , respectively; (ii) an overprint check means determines whether an overprint has been measured and separately measures and stores the first down color red, green and blue optical densities and the second down color red, green and blue optical densities; (iii) a percent trap means determines percent trap from said measured optical densities of said over­print and said first and second down colors; and (iv) a percent trap display means displays the percent trap to the pressman for use in controlling the printing process.

Claim 25

A densitometer system for a printing pro­cess comprising measuring means for measuring the red, green, blue and visual optical densities of a selected target; first comparison means for determining, from said measured optical densities, whether an unprinted substrate is detected and, if so, displaying this fact to the pressman, whereupon said measuring means measures a different target; second comparison means for determining, where an unprinted substrate is not detected, whether a solid black has been measured and, if so, displaying this fact to the pressman and storing the measured visual optical density as the correspond­ing solid visual density, whereupon said measuring means measures a different target; third comparison means for determining, where neither an unprinted sub­strate nor a solid black are detected, whether a solid color target has been measured, whereupon the greatest of the measured red, green or blue optical densities is stored by a solid density value storage means as the corresponding solid color density and said measuring means measures a different target; and percent dot area means for determining whether a halftone is de­tected, whereupon said percent dot area means determines and displays percent dot area based on said measured optical density and said stored solid density values.

Claim 26

A densitometer system for a printing pro­cess comprising measuring means for measuring the red, green, blue and visual optical densities of a selected target; first comparison means for determining, from said measured optical densities, whether an unprinted substrate is detected and, if so, displaying this fact to the pressman, whereupon said measuring means measures a different target; second comparison means for determining, where an unprinted substrate is not detected, whether a solid black has been measured and, if so, displaying this fact to the pressman and storing the measured visual optical density as the correspond­ing solid visual density, whereupon said measuring means measures a different target; third comparison means for determining, where neither an unprinted sub­strate nor a solid black are detected, whether a solid color target has been measured, whereupon the greatest of the measured red, green or blue optical densities is stored by a solid density value storage means as the corresponding solid color density and said measuring means measures a different target; and percent dot area means for determining whether a halftone is de­tected, whereupon said percent dot area means determines and displays percent dot area based on said measured optical density and said stored solid density values.