We can custom any styles any size of Electric Facial Bed, Hydraulic Facial Bed, wood Facial Bed , Massage Table, facial bed, facial massage chair, Shampoo Chair , Barber Chair , styling chair, child chair, Waiting Chair , dressing mirror, reception table, pedicure chair,pedicure bed,spa bed,pedicure spa, spa furniture, Nail Table , massage chair, master chair, trolley, Bed Cover , footstep and cushion according to your requirements.
Q1:
What`s the stand delivery period?
A:Normally,
It takes 25-30days for the LCL shipment, 35-40 days for the FLC shipment for
your ref.
Please
subject the confirmation from the sales when you place order.
Q2:
How about payment term?
A:FOB
JIANGMEN for FCL, 30% deposit before production and 70% balance before
shipment.
T/T,
western union are available.
Please
subject to the confirmation when you sign the contract.
Q3:
What's the shipping cost?
A:
Shipping cost will be checked once have your interested models, order quantity
and delivery port.
Q4:How
about warranty?
A:
The warranty period is one year after the delivery date.
Q5:Can
you do customize design or OEM?
A:
Yes, We have our own professional R&D team for customize design and OEM.
There are two commonly used dot area calculation formulas: Murray2Davies formula and Yule2Nielson formula. Murray2Davies formula is relatively simple, the application is also the most, the general density meter uses this formula for the conversion of the dot area. Experiments have shown that the accuracy of the Mur2ray2Davies formula can be improved by properly setting the value of n. Mathematically speaking, if a limit condition can be determined, such as knowing the exact dot area corresponding to a certain tone density, the value of n can be found. However, since the printing process is very complicated, it is impossible to obtain an accurate dot area of ​​a certain density, and it is actually very difficult to determine the value of n. Although many people have studied this in more detail, the value of n has not been unified so far. According to the data, the n value of the coated paper ranges from 112 to 210, and the n value of the non-coated paper ranges from 118 to 510. Since the n value acts on the index, its change has a great influence on the calculation result, and if it is not properly selected, it is even more effective. The calculation accuracy decreases.
In order to further explain the problem of density and dot area calculations, the actual measured and calculated data are compared. Table 1 lists the density measurement values ​​for the printing scales of the primary ink and the corresponding dot counts. The scale was obtained by offset proofing with 128 g coated paper, and the measuring instrument was a X2 Rite 528 spectrodensitometer. The relative density values ​​DT-DW and DS-DW can be measured directly by the instrument; the calculated dot values ​​are calculated using Equation (7); the measured dot values ​​are measured directly by the instrument. From the data listed in Table 1, it can be seen that the calculated network point value is consistent with the measurement network point value, and the phase difference is within the measurement error range, which indicates that the instrument is also using the formula (7) to calculate the dot area.
It should be pointed out that in the table, the corresponding dot values ​​of n=1.5 (relative) and n=1.8 (relative) are calculated using the formula of Yule 2 Nielson and the relative density value (the obtained range of printed n-values ​​for coated paper is generally 115 ~ 118). The calculated data shows that the value of n has a great influence on the calculation result, especially in the highlight region. From the high light to the midline area, the dot value appears to be smaller, and the calculation result is obviously unreasonable. The error is rather increased. From the general trend, the calculated value of the dot area decreases as the value of n increases. This has a great influence on the highlight region and has no obvious influence on the shadow region. For further verification, comparative calculations were again performed using the Yule 2 Nielson formula and the absolute density values. The results are shown in Table 1n=1.5 (absolute) and n=1.8 (absolute). These data appear to be more reasonable than those calculated using relative density values. The value of n here is arbitrarily set, and the calculation result is not always ideal, but it is possible to find a more suitable value of n to make the calculation result more accurate.
From the above data, it can be seen that the selection of the correction coefficient n has a great influence on the calculation result. In this experiment, the results are not ideal whether they are calculated using absolute density values ​​or relative density values. Therefore, it is recommended that you do not use the Yule 2 Nielson formula to calculate if you cannot measure n accurately.
2 Use colorimetric values ​​for dot area calculation
With the development of printing technology, more and more calculations have been made on the basis of the theory of colorimetry, especially in terms of prepress and printing color control. The color calculation is basically performed in the CIEXYZ standard color space and the CIEL3a3b3 uniform color space, such as a color management system. With the decrease in the price of colorimeters, many companies have enhanced the testing methods to increase the quality of printed products, and have purchased colorimetric instruments one after another. This will become the orientation of future testing methods. Therefore, it is of great significance to explore the method of calculating the dot area of ​​the printing using the colorimetric measurement values.
According to the principle of color addition, the relationship between the chroma value and the dot area can be easily deduced.
It is not difficult to see that the dot area calculated with the chromaticity value is close to the direct measurement value, which shows that the method of calculating the dot area using the chromaticity value is feasible.
3 Discussion
Accurate measurement or calculation of dot area is a difficult task because of the lack of an accurate measurement reference. Due to the fact that the accuracy of the absolute measurement of the dot area in actual production is not high, the relative value can be used as a control function, so it is usually replaced by an approximation. The X2Rite528 spectrodensitometer used in this experiment is a relatively high-end instrument that not only measures density and dot area, but also measures chroma, color difference, overprint, print contrast, etc. It can also detect ink hue error and gray scale. When measuring the dot area, you can either select the Murray2Davies formula (n=1) or select the Yule2Nielson formula (n≠1) to calculate. The n value can be set by the user. For a general type of densitometer, the user cannot set the value of n when measuring the dot area. The instrument is calculated according to the Murray2Davies formula. The X2Rite528 spectrodensitometer was calculated with relative density values ​​using the Murray2Davies formula and the Yule2Nielson formula. As mentioned earlier, when using the formula of Yule2Nielso, it is more reasonable to take the absolute density value. If you take the relative density value to calculate at the same time to choose the correction coefficient n value, it seems to be somewhat difficult to understand. Since the density value of the paper itself has been subtracted from the relative density value, and the value of n is set to compensate for the paper seepage effect, it is equivalent to double correction. On the other hand, it is difficult to determine the accuracy of n in practical applications. The results of the previous calculations and actual measurements show that if the value of n is not properly selected, the accuracy of calculation will decrease. Therefore, correcting the error with n value is not the best method and should be carefully selected in practical applications.
According to the principle of print coloration, this paper proposes a formula for calculating the dot area based on the chroma value. In fact, the color calculation method and the density calculation method are based on the same principle. They are all based on the principle of the absorption and reflection of light by the color of printed matter. The measurement conditions are also the same, except that the method of processing spectral data is different. Density measurement uses T, E, A, and other types of color filters, while colorimetry uses a unified CIE1931 standard observer function. Colorimetry is based on human vision, and the theory is relatively perfect. Using this method to calculate dot area should be a more reasonable method. The Neugebauer equation is based on the principle of color addition. This principle is the most basic rule of colorimetry. Therefore, the physical meaning of the dot area calculated by this method is clearer, and there is no theoretical error. Comparing the data in Table 1, it can be found that the results of direct measurement, density method calculation and chroma method calculation are very similar. Due to the lack of accurate reference standards, it is difficult to prove which method is better. In the next step, it can be verified more precisely with the aid of scanning magnification. However, from the principle analysis and calculation results, if the results calculated using the Murray2Davies formula can meet the accuracy requirements, then the method for calculating the dot area using the chromaticity values ​​proposed in this paper is also fully able to meet the requirements. In practical applications, if the printing process is controlled by measuring the dot area, then using the colorimetric method to calculate the dot area can fully play a role.
Another advantage of using the colorimetric method to calculate the dot area is that the overprinted dot area can be calculated. This can be obtained by solving the two-color and three-color Neugebauer equations. Calculating the dot area by the density method is based on the complementary color density, and the complementary color density can only be obtained from the measurement of the monochrome sample, and it is inconvenient to calculate the dot area of ​​the multi-color overprinting.
From the calculation results, it can be seen that the effect of the correction coefficient n is mainly to reduce the dot value of the high-to-medium adjustment region, and has little effect on the dark tone region. Compared with the results of direct measurement, density method calculation, and colorimetry calculation, except for the yellow ink high-profile area, the color point calculated by the colorimetric method has a slightly smaller value than the measured value, which can be said to partially contain the effect of compensating n-values.
Manicure Pedicure Spa Chair ,Pedicure Spa Chair,European Pedicure Spa Chair,Electric Pedicure Spa Chair
ChaoHui Beauty Salon Equipment Co., Ltd. , https://www.chaohuibeauty.com