No, they are not the same.
All paper, and in fact several white surfaces, are measured for both Whiteness and Brightness.
Both measure and represent a slightly different aspect of how we perceive a paper's visual appearance.
The International Commission on Illumination - CIE (also, Commission Internationale de l'Eclairage) has set the standard for measuring whiteness.
The most common standards for measuring brightness of paper is set by ISO and TAPPI.
So you will find most paper specification sheets to separately declare the 'ISO Brightness' and 'CIE Whiteness' values for a given grade of paper.
WHITENESS
The concept of paper whiteness is closely related to how the human eye perceives color, and it involves various factors that contribute to the visual appearance of a white or near-white surface. Here are key aspects of paper whiteness in the context of human color perception:
Reflectance Spectrum: The color of an object, including paper, is determined by the wavelengths of light it reflects. White surfaces are those that reflect all visible wavelengths of light, resulting in a balanced spectrum. Paper whiteness takes into account the distribution of reflectance across the visible spectrum.
CIE Color Space: The International Commission on Illumination (CIE) has defined a color space that describes how humans perceive colors. In this context, paper whiteness is often assessed using CIE coordinates. A perfectly white surface would have coordinates close to the center of the CIE chromaticity diagram, representing a neutral appearance.
Paper whiteness is a complex perceptual concept that considers not only the absence of color but also the balance of colors across the visible spectrum. The interaction of ambient light, the texture characteristics of the paper, and the viewer's visual system collectively contribute to the perception of paper whiteness.
CIE Whiteness values are typically expressed as a percentage, with higher values indicating a closer match to a perfect white reference. The scale ranges from 0% (no whiteness) to 100% (perfect whiteness). Here are some general guidelines for interpreting CIE Whiteness values:
0-40%: Materials with lower CIE Whiteness values may appear off-white or have a noticeable color tint.
40-70%: Moderate CIE Whiteness values suggest a fair level of whiteness, though some color tint may still be perceptible.
70-100%: Higher CIE Whiteness values approach or achieve perfect whiteness, indicating that the material appears visually close to a perfect white reference.
Note - in real world applications, paper mills will generally add what are called 'OPTICAL BRIGHTNING AGENTS or just OBAs' to increase the perceived whiteness of the paper, and this often results in CIE values above 130. OBAs also bump up ISO Brightness values.
Its important to understand that the application of the paper will define the desired whiteness value.
BRIGHTNESS
ISO (International Organization for Standardization) Brightness, on the other hand, is a measure of the reflectance of blue light at a specific wavelength (457 nanometers) from the surface of a material.
It is a more specific measure than CIE Whiteness and focuses on the ability of the material to reflect blue light, which is a key component of the visible spectrum.
ISO Brightness is commonly used in the paper industry, especially for printing and photographic papers, to assess how "bright" the paper appears.
To summarize...
Without getting too technical about it - the ISO Brightness value of a given paper indicates how 'bright' the paper appears, and it does not talk about the actual 'shade of white' that the paper is.
When we say 'shade of white' - we intuitively know what it means as we have all seen papers varying from bluish to sort of cream / off-white tones and of course perfectly neutral white papers somewhere on that spectrum. This is in the realm of CIE Color LAB Model (l*, a*, b*).
So brightness is a measure of how bright the paper appears, and Whiteness is a measure of how closely a paper approaches a perfect neutral white on the CIE Chromaticity diagram.
As your private label manufacturing partner for paper stationery and related products, we will take you through the paper selection process to zero down on the right paper for your product and market.
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