How is whiteness calculated?
For this, the formula most often used is the Ganz–Griesser formula W = (D × ϒ) + (P · x) + (Q · y) + C, where Y, x, y are the colorimetrically determined values for lightness, and the CIE chromaticity coordinates, D, P, Q, C, are the formula parameters whose magnitude is determined by the “whiteness preference” (“taste …
What is white index?
Typically, this whiteness index is a preference rating for how white a material should appear, be it photographic and printing paper or plastics. Thus Whiteness Index is a measure which correlates the visual ratings of whiteness for certain white and near-white surfaces.
What is degree of whiteness?
In colorimetry, whiteness is the degree to which a surface is white. An example of its use might be to quantitatively compare two pieces of paper which appear white viewed individually, but not when juxtaposed.
What is whiteness test?
In statistics, the White test is a statistical test that establishes whether the variance of the errors in a regression model is constant: that is for homoskedasticity. This test, and an estimator for heteroscedasticity-consistent standard errors, were proposed by Halbert White in 1980.
What is the difference between whiteness and brightness?
Paper brightness measures the amount of light reflected from the surface of paper at one specific wavelength (457 nm) in the blue region of the spectrum, whereas whiteness measures the relative balance of light reflected across the full visible spectral range (approximately 380nm – 720nm).
What is Berger whiteness?
Berger – this whiteness index is specified for illuminant C and 2-degree observer functions only. However, the equation is commonly used with other illuminants and observer functions, therefore the value shown will depend on the primary illuminant and the observer function you have chosen.
What is the instrument used for measuring whiteness of linen?
Evaluating the level of whiteness of linens objectively requires color measuring instrument such as Konica Minolta CR-20 color reader. Suitable for on-site use, the CR-20 color reader is capable of measuring whiteness index and is popular in many laundry houses for quick, easy and objective evaluation.
How is yellowness measured?
Yellowness indices are used chiefly to measure these types of degradation. Where X, Y, and Z are the CIE Tristimulus values, and the coefficients depend on the illuminant and observer as indicated in the table below….Yellowness Index.
| C/2 | D65/10 | |
|---|---|---|
| CX | 1.2769 | 1.3013 |
| CZ | 1.0592 | 1.1498 |
What is ASTM E313?
Yellowness Index (YI) ASTM E313. Scope: Yellowness Index is a number calculated from spectrophotometric data that describes the change in color of a test sample from clear or white to yellow. This test is most commonly used to evaluate color changes in a material caused by real or simulated outdoor exposure.
What is whiteness index of a fabric?
It is the measure which correlates the visual ratings of whiteness for certain white and near-white surfaces. The two most commonly used methods for computing a whiteness index are: CIE Whiteness Index and Ganz-Griesser Whiteness Index.
How do you test white linen?
What is the best brightness for paper?
Black text tends to stand out on most paper brightness levels, so text documents only need an ordinary level brightness in the 80s and low 90s when measured on a scale of 100. A colorful design or fine-art reproduction may require the highest level of brightness.
What is good GSM for paper?
Weight (gsm) 80gsm is standard. Anything from 160gsm is considered card. GSM is a good guide to quality. 60gsm paper will seem flimsy and see-through compared to 100gsm weight or 120gsm weight paper.
What GSM is normal paper?
80-110 GSM
80-110 GSM: the most common weight used for all general printing, including letterheads.
What is the yellowness index?
How fabric whiteness can be increase?
Temperature has a steady influence on whiteness index which is enhanced further by peroxide concentration. However the individual effect of peroxide concentration on whiteness index is pretty low and no change in whiteness is found at higher concentrations if temperature remains constant.
How do you lighten white linens?
If you want to lighten your linens, follow these steps for bleaching white sheets.
- Machine wash sheets with regular laundry detergent.
- Add ½ cup of bleach to the drum of the machine and run a regular cycle.
- If the bleach smell persists, run another cycle with regular laundry detergent and hydrogen peroxide.
What is the whiteness index?
It is the measure which correlates the visual ratings of whiteness for certain white and near-white surfaces. The two most commonly used methods for computing a whiteness index are: CIE Whiteness Index and Ganz-Griesser Whiteness Index. The CIE Whiteness Index
How do you calculate the whiteness index of an illuminant?
Berger – this whiteness index is specified for illuminant C and 2-degree observer functions only. However, the equation is commonly used with other illuminants and observer functions, therefore the value shown will depend on the primary illuminant and the observer function you have chosen. The formula is: WI=Y+0.3018Z-3.831X.
What is the formula for Hunter whiteness index?
The more commonly known Hunter Whiteness Index was defined in 1960 based on the Hunter L, a, b scale for C/2 conditions. WI H = 100 – { [220 (G – B) / (G + 0.242 B)] 2 + [ (100 – G)/2] 2 } 1/2 (C/2)
How do you calculate the index of a white point?
The indices can be calculated, rounded, and adjusted in the last retained significant digit to minimize the residual error in the white point values. The equation is: YI=100 (CxX-CzZ)/Y, where Cx and Cy standard coefficients described in the standard and correspond with observer angle and color temperature.