Densitometer method and system for identifying and analyzing printed targets

A method for recognizing the type of printed target and controlling a multi-color printing process comprising the steps of:

• measuring the red, green, blue and 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 an unprinted substrate has been measured, displaying that an unprinted substrate has been measured 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 a solid black target has been read, storing the measured visual optical density as S.sub.V, displaying that a solid black target has been read, and repeating the above measuring step at a different target location;
• whether 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 an overprint has been measured, 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 than 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, that a muddy solid magenta has been read is displayed, the measured green optical density is stored as S.sub.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.sub.r, T.sub.g and T.sub.b, respectively,
• (ii) measuring the red, green and blue optical densities of the first down color and storing these values as T.sub.1r, T.sub.1g and T.sub.1b, respectively,
• (iii) measuring the red, green and blue optical densities of the second down color and storing the greatest measured value as T.sub.2,
• (iv) calculating percent trap using the equation ##EQU5## where T and T.sub.1 are the overprint and first down color density values corresponding to the filter color designated as T.sub.2, and
• (v) displaying percent trap, 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 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 a solid color target has been measured, storing the largest of the measured red, green or blue optical density as the corresponding solid density S.sub.r, S.sub.g, S.sub.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 ##EQU6## where:
• D.sub.h =the largest measured halftone density,
• S=the solid density corresponding to D.sub.h,
• n=Yule-Nielsen factor,
• the percent dot are being displayed;
• controlling the printing process based upon the information generated and displayed in the foregoing steps.

A densitometer system for recognizing the type of target in a multi-color 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 an unprinted substrate is detected, displaying than an unprinted substrate is detected, 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 that a solid black has been measured, displaying that a solid black has been measured 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 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.sub.r, T.sub.g, T.sub.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, whereafter said measuring means measures a different target;
• 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.

A densitometer system for recognizing the type of target in a multi-color 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 stored constant K1 to determine whether an unprinted substrate has been measured and, if an unprinted substrate has been measured, displaying that an unprinted substrate has been measured, 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.sub.v, that a solid black target has been read is displayed 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, green and 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, that a muddy solid magenta has been read is displayed, the measured green optical density is stored as S.sub.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 that an overprint has been measured, said overprint check means,
• (i) stores the measured red, green and blue optical densities as overprint values T.sub.r, T.sub.g and T.sub.b, respectively,
• (ii) measures the red, green and blue optical densities of the first down color and stores these values as T.sub.1r, T.sub.1g and T.sub.1b, respectively,
• (iii) measures the red, green and blue optical densities of the second down color and stores the greatest measured value as T.sub.2,
• (iv) calculates percent trap using the equation ##EQU8## where T and T.sub.1 are the overprint and first down color density values corresponding to the filter color of the density value designated T.sub.2,
• (v) displays percent trap, whereupon said measuring means measures a different target portion;
• 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 a solid color target has been measured, storing the greatest measured optical density as the corresponding solid optical density, S.sub.r, S.sub.g or S.sub.b ;
• and
• percent dot area means for comparing, where an unprinted substrate, a black solid, a muddy magenta, an overprint or a color solid 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 equation ##EQU9## where:
• D.sub.h =the largest measured halftone density,
• S=the solid density corresponding to D.sub.h,
• n=Yule-Nielsen factor, and
• said percent dot area means displaying either the calculated percent dot area of an error signal where no value has been stored for the corresponding solid density.

A densitometer system for recognizing the type of target in a multi-color 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 at T.sub.r, T.sub.g, T.sub.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.

A densitometer system for recognizing the type of target in a multi-color 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 an unprinted substrate is detected, displaying that an unprinted substrate is detected, 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 a solid black has been measured, displaying that a solid black has been measured 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 black solid 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.