【色度学】 颜色
1. 前言
一直对色彩感兴趣，不光是因为专业的原因，本来世界就是五彩斑斓的嘛。
前端时间猛看了之前积累下来的资料，自觉有点明白了。先做个记号，有时间总结一下
2. 基本概念
其实我们平时看到的关于色彩的名词使用非常混乱，本着认真严谨的研究态度
，他们应该被严格的定义和区分开
基本上，是客观和主观，真实世界和人类感官世界的区别。是哲学上唯物和唯心的区别。。。。。
Radiometry描述物理的客观世界中光线的能量和辐射分布状况等，光度学定义人类的视觉系统对这些能量的响应情况以及人脑神经中枢产生的对应响应。
常用的RGB，HSV，HSI，HSB等颜色模型并不符合人眼对色彩的感受，这些名字缩写中的Hue，Saturation，Intensity也和严格的色度学中的相同名词的定义有所差别.
The Basics of Radiometry and Photometry
Radiometry： 辐射学（没找到准确的翻译）
Photometry： 光度学
Radiometry is the science that allows us to answer “how much light is there?”
Photometry is the same, but scaled to the average human visual response.
Photometry is, in essence, radiometry weighted by the spectral response of vision.
Radiometry中的四个基本单位：flux, irradiance, radiant intensity, radiance分别对应Photometry中的四个常用量值：lunimous flux，illuminance，luminous intensity，luminance。有时间画个表格，把它们相应的定义和衡量单位比较一下
HSL and HSV
The dimensions of the HSV and HSL geometries – simple transformations of the not-perceptually-based RGB model – are not directly related to the photometric color-making attributes of the same names, as defined by scientists such as the CIE or ASTM. Nonetheless, it is worth reviewing those definitions before leaping into the derivation of our models
- Hue
- The "attribute of a visual sensation according to which an area appears to be similar to one of the perceived colors: red, yellow, green, and blue, or to a combination of two of them".
- Intensity, radiance
- The total amount of light passing through a particular area.
- Luminance ( Y)
- The radiance weighted by the effect of each wavelength on a typical human observer, measured in candela per square meter (cd/m 2). Often the term luminance is used for the relative luminance, Y/ Y n, where Y n is the luminance of the reference white point.
- Luma ( Y′)
- The weighted sum of gamma-corrected R′, G′, and B′ values, and used in Y′CbCr, for JPEG compression and video transmission.
- Brightness
- The "attribute of a visual sensation according to which an area appears to emit more or less light".
- Lightness, value
- The "brightness relative to the brightness of a similarly illuminated white".
- Colorfulness
- The "attribute of a visual sensation according to which the perceived color of an area appears to be more or less chromatic".
- Chroma
- The "colorfulness relative to the brightness of a similarly illuminated white".
- Saturation
- The "colorfulness of a stimulus relative to its own brightness".
Brightness and colorfulness are absolute measures, which usually describe thespectral distribution of light entering the eye, while lightness andchroma are measured relative to some white point, and are thus often used for descriptions of surface colors, remaining roughly constant even as brightness and colorfulness change with differentillumination.Saturation can be defined as either the ratio of colorfulness to brightness or of chroma to lightness.
色盲的种类 (没查单词，希望理解对了)