CN103057292B - Printer calibration algorithm based on characteristics of human eye - Google Patents

Abstract

The invention discloses a printer calibration algorithm based on characteristics of a human eye. The calibration algorithm provided by the invention comprises the following steps: obtaining a calibrated sample by printing calibration ink formulae; measuring the calibrated sample to obtain a measurement spectrum; and predicting a prediction spectrum of the calibration ink formula by using a former model, and calculating to obtain a calibration coefficient by combining a polynomial and the sum in all wavelengths of CIE standard 1964 color observer tristimulus-value functions representing the characteristics of the human eye, so that a printer is calibrated. The printer calibration algorithm provided by the invention has the advantages of being simple in application and high in precision, is applicable to calibrating various printer spectrum characteristic models, and has a very high practical value.

Description

Printer scaling algorithm based on human eye characteristic

Technical field

The present invention relates to a kind of scaling algorithm of printer, specifically relate to a kind of printer scaling algorithm based on human eye characteristic.

Background technology

Along with the development of industrial technology, printer is widely used in daily life.Meanwhile, a large amount of scientific workers have carried out corresponding research to the ink color management of printer.At present, a relevant spectrum characterization model that study hotspot is exactly printer, this model can be predicted its spectroscopic data after a certain paper is printed from ink set (being each ink consumption).Existing printer spectrum characterization model mainly contains three dimensional lookup table method, Yule-Clapper model and improved model thereof, Neugebauer model and improved model thereof etc.

With regard to current technology, set up a high-precision printer spectrum characterization model at least needs to print and measure several thousand samples, therefore set up a spectral model, is more time-consuming, a to require great effort engineering.But the precision of prediction of final mask is still subject to the restriction of a plurality of factors, as replacing of the uniformity of the repeatability of printer, paper, environment temperature, ambient humidity, print cartridge etc.In order to solve this problem on the one hand, just need to print the calibration of machine, by the contact between the model of printing some Sample Establishings and set up under existing print conditions (hereinafter referred " master mould "), thereby realize the high-precision forecast of master mould under existing print conditions.Although also have some about the research of printer calibration aspect at present, but all printer scaling algorithms are not all considered the characteristic of human eye, and the color printing passes judgment on to people or appreciate, therefore, propose a printer scaling algorithm based on human eye characteristic and be necessary.

Summary of the invention

The present invention, in order to solve the problem described in background technology, discloses a kind of printer scaling algorithm based on human eye characteristic.This method is in conjunction with multinomial and represent that CIE (International Commission on Illumination) standard colorimetric observer's of human eye characteristic spectral tristimulus value function realizes the calibration of printer, and its concrete steps are as follows:

1) choose n the basic calibration ink set that covers each look district, general n is 30-50;

2) utilize the printer that adopts while setting up master mould and the printing sample of paper output calibration ink set, calibrate sample, and it is fully dry to guarantee ink that calibration sample is placed to a period of time in darkroom;

3) adopt a spectrophotometer to measure all calibration samples, record its corresponding measure spectrum R _m(λ), wherein subscript m represents to measure, and λ represents wavelength;

4) utilize master mould to record in advance prediction spectrum R to all calibration ink sets _p(λ), wherein, subscript p represents prediction;

5) adopt CIE1964 standard colorimetric observer's tristimulus values function x (λ), y (λ) and z (λ) at each wavelength sum S (λ) as human eye characterisitic function;

6), for wavelength X, suppose R _m(λ), R _p(λ) and S (λ) meet following quadratic polynomial formula:

S(λ)×R _m(λ)＝a(λ)×[S(λ)×R _p(λ)] ²+b(λ)×S(λ)×R _p(λ)+c(λ)

Wherein, a (λ), b (λ) and c (λ) are calibration coefficient;

7), according to least square method, calculate final calibration coefficient a (λ), b (λ) and c (λ);

8), for arbitrary ink set, can first by master mould, predict its spectrum R ' _p(λ), then according to step 6) in formula and step 7) in calibration coefficient a (λ), the b (λ) and the c (λ) that calculate, can try to achieve the spectrum R ' after final calibration _m(λ), its value is

R’ _m(λ)＝{a(λ)×[S(λ)×R’ _p(λ)] ²+b(λ)×S(λ)×R’ _p(λ)+c(λ)}/S(λ)。

The present invention is by printing and measure the measure spectrum that obtains of calibration sample, and the prediction spectrum of master mould, realizes the calibration of printer in conjunction with multinomial and human eye characteristic.This invention application is simple, precision is high, have very high practical value.

Accompanying drawing explanation

Fig. 1 is the printer scaling algorithm flow chart based on human eye characteristic;

Fig. 2 is CIE1964 standard colorimetric observer's tristimulus values function x (λ), y (λ) and z (λ);

Fig. 3 is CIE1964 standard colorimetric observer's tristimulus values function sum S (λ);

Fig. 4 is final calibration coefficient a (λ), b (λ) and the c (λ) calculating in embodiment;

The specific embodiment

The Yule-Clapper spectral model set up (hereinafter referred " former YC model ") of a black CMYK of HP Designjet1055CM tetra-(blue or green product Huang is black) four black printers and based on this printer of take is example, and the specific embodiment of the above-mentioned printer scaling algorithm based on human eye characteristic is set forth.As shown in Figure 1, its concrete steps are as follows:

1) choose 40 basic calibration ink sets that cover each look district, the i.e. combination of each ink consumption of CMYK;

2) utilize the printer that adopts while setting up master mould and the printing sample of paper output calibration ink set, calibrate sample, and by calibration sample in darkroom, place 1 hour fully dry to guarantee ink;

3) adopt Datacolor650 spectrophotometer to measure all 40 calibration samples, record its corresponding measure spectrum R _m(λ), wherein subscript m represents to measure, and λ represents wavelength, and measurement category is that 400nm be take 10nm as interval to 700nm;

4) utilize former YC model to record in advance prediction spectrum R to all calibration ink sets _p(λ), wherein, subscript p represents prediction;

5) adopt CIE1964 standard colorimetric observer's tristimulus values function x (λ), y (λ) and z (λ) at each wavelength sum S (λ) as human eye characterisitic function.Wherein, as shown in Figure 2, CIE1964 standard colorimetric observer's tristimulus values function sum S (λ) as shown in Figure 3 for CIE1964 standard colorimetric observer's tristimulus values function x (λ), y (λ) and z (λ);

6), for wavelength X, suppose R _m(λ), R _p(λ) and S (λ) meet following quadratic polynomial formula:

S(λ)×R _m(λ)＝a(λ)×[S(λ)×R _p(λ)] ²+b(λ)×S(λ)×R _p(λ)+c(λ)

Wherein, a (λ), b (λ) and c (λ) are calibration coefficient;

7), according to least square method, calculate final calibration coefficient a (λ), b (λ) and c (λ), as shown in Figure 4;

8), for arbitrary ink set, can first by master mould, predict its spectrum R ' _p(λ), then according to step 6) in formula and step 7) in calibration coefficient a (λ), the b (λ) and the c (λ) that calculate, can try to achieve the spectrum R ' after final calibration _m(λ), its value is

R’ _m(λ)＝{a(λ)×[S(λ)×R’ _p(λ)] ²+b(λ)×S(λ)×R’ _p(λ)+c(λ)}/S(λ)。

Claims (2)

1. the printer scaling algorithm based on human eye characteristic, is characterized in that comprising the following steps:

1) choose n the basic calibration ink set that covers each look district, n is 30-50;

2) utilize the printer that adopts while setting up master mould and the printing sample of paper output calibration ink set, calibrate sample, and it is fully dry to guarantee ink that calibration sample is placed to a period of time in darkroom;

3) adopt a spectrophotometer to measure all calibration samples, record its corresponding measure spectrum R _m(λ), wherein subscript m represents to measure, and λ represents wavelength;

4) utilize master mould to record in advance prediction spectrum R to all calibration ink sets _p(λ), wherein, subscript p represents prediction;

5) adopt CIE1964 standard colorimetric observer's tristimulus values function x (λ), y (λ) and z (λ) at each wavelength sum S (λ) as human eye characterisitic function;

6), for wavelength X, suppose R _m(λ), R _p(λ) and S (λ) meet following quadratic polynomial formula:

S(λ)×R _m(λ)＝a(λ)×[S(λ)×R _p(λ)] ²+b(λ)×S(λ)×R _p(λ)+c(λ)

Wherein, a (λ), b (λ) and c (λ) are calibration coefficient;

7), according to least square method, calculate final calibration coefficient a (λ), b (λ) and c (λ);

8), for arbitrary ink set, can first by master mould, predict its spectrum R ' _p(λ), then according to step 6) in formula and step 7) in calibration coefficient a (λ), the b (λ) and the c (λ) that calculate, can try to achieve the spectrum R ' after final calibration _m(λ), its value is

R’ _m(λ)＝{a(λ)×[S(λ)×R’ _p(λ)] ²+b(λ)×S(λ)×R’ _p(λ)+c(λ)}/S(λ)。

2. the printer scaling algorithm based on human eye characteristic according to claim 1, it is characterized in that described step 5) in adopt CIE1964 standard colorimetric observer's tristimulus values function x (λ), y (λ) and z (λ) the maximum of each wavelength replace CIE1964 standard colorimetric observer's tristimulus values function x (λ), y (λ) and z (λ) at each wavelength sum S (λ) as human eye characterisitic function, or employing CIE1931 standard colorimetric observer's tristimulus values function replacement CIE1964 standard colorimetric observer's tristimulus values function.