## 2015-04-30

### #Docker 的演講

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## 2015-04-25

### 自製冰火菠蘿油

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## 2015-04-19

### 卡士達葡萄塔

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### Breakfast

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## 2015-04-13

### R.app warning on Mac

If install R.app on a Mac without default locale setting to UTF-8, warning message comes up while starting up R.app. The warning message is as follows:

To solve this issue, close R.app and type following command in terminal.
\$> defaults write org.R-project.R force.LANG en_US.UTF-8
Relaunch R.app and the warning disappears.

Reference
[1] http://cran.r-project.org/bin/macosx/RMacOSX-FAQ.html#Internationalization-of-the-R_002eapp

## 2015-04-06

### 深奧Whisky

Malt Whisky

Single Malt Whisky

Scotch Whisky

Single Malt Scotch Whisky

Single Cask

Vatted Malt

Blended Malt

Grain Whisky

Blended Scotch Whisky

Whisk(e)y
Whisky與Whiskey是相同的，一般的誤解是美式英文的拼法與英式英文拼法的不同。但事實上是指whisky類型的不同，蘇格蘭及加拿大生產的會用whisky；而愛爾蘭生產的會用whiskey；美國生產的多用whiskey，但有的廠牌也使用whisky。

Reference
[1] Michael Jackson's Malt Whisky Companion 6th Edition
[2] 漫畫威士忌入門 (古谷三敏)

## 2015-04-04

### 橄欖油櫻桃鴨胸，微辣，好吃

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## 2015-04-02

### Color terms

Additive color
Color created by mixing a number of different light colors. Adding red, green and blue together forms like sun light so the color becomes white.

Subtractive color
Color created by mixing dyes or inks. The color of dyes or inks is the only visible spectrum reflecting to eyes and other visible spectrum are absorbed. Hence the color mixed by red, green and blue together absorbs all visible spectrum and the color is black.

Hue
Map colors to a cyclic color wheel.

Saturation
Saturation is one type of colorfulness. The saturation of a color is determined by a combination of light intensity and how much it is distributed across the spectrum of different wavelengths.

HSL and HSV
HSL (hue-saturation-lightness) and HSV (hue-saturation-value) are cylindrical-coordinate representations of points in an RGB color model.

Chromaticity
An objective specification of the quality of a color regardless of its luminance. Chromaticity consists of two independent parameters, often specified as hue (h) and colorfulness (s).

CIE color space
Human eye has three kinds of cone cells, which sense light, with spectral sensitivity peaks in short (S, 420-440nm), middle (M, 530-540nm) and long (L, 560-580nm) wavelengths. Three parameters (S, M, L), corresponding to levels of stimulus of the three types of cone cells, can in principle describe any color sensation, called LMS color space.

A color space maps a range of physical produced colors to an objective description of color sensations registered in the eye, typically in terms of tristimulus values. The tristimulus values associate with a color space can be conceptualized as amounts of three primary colors in a tri-chromatic additive color model.

Most wavelengths will not stimulate only one type of cone cell due to overlap of spectral sensitivity curves. LMS tristimulus values for pure spectral colors would imply negative values for at least one of these three primary colors. To avoid negative RBG values and to have one component describing brightness, "imaginary" primary colors and corresponding color-matching functions have formulated. The resulting tristimulus values are X, Y, Z (XYZ color space).

Humans tend to perceive light within green parts of the spectrum as brighter than red or blue. The luminosity function that describes the perceived brightness of different wavelengths is thus roughly analogous to M.

CIE model defines Y as luminance, Z is quasi-equal to blue stimulation (S cone response), and X is a mix of cone response curves chosen to be non-negative.

The chromaticity of a color is specified by two derived parameters x and y, two of the three normalized values which are functions of all three tristimulus values, X, Y and Z.

The derived color space specified by x, y and Y is known as xyY color space and is widely used to specify colors in practice.

CIE Chromaticity Diagram
The outer curved boundary is the spectral locus, with wavelengths in nanometers. This diagram represents all of the chromaticities visible to average person. All visible chromaticities correspond to non-negative values of x, y and z.

Reference
[1] https://en.wikipedia.org/wiki/Additive_color
[2] https://en.wikipedia.org/wiki/Subtractive_color
[3] https://en.wikipedia.org/wiki/Hue
[4] https://en.wikipedia.org/wiki/Colorfulness
[5] https://en.wikipedia.org/wiki/HSL_and_HSV
[6] https://en.wikipedia.org/wiki/Chromaticity
[7] https://graphics.stanford.edu/courses/cs178-10/applets/threedgamut.html
[8] https://en.wikipedia.org/wiki/CIE_1931_color_space
[9] https://en.wikipedia.org/wiki/Color_space

## 2015-04-01

### Photometry terms

Luminous flux 光通量 (phi)
The amount of light radiated by a light source per second, and the unit is Lumen (lm). Often used to specify the total amount of light emitted by a lamp. It does not specify the directions in which the light is radiated.

Luminous intensity 光度 (I)
The amount of light that travels in certain directions from the source, and is measured in Candelas (cd).

Illuminance 照度 (E)
The amount of light falling on a surface is illuminance, and the unit is Lux (lm/m^2).

Luminance 亮度 (L)
The light is reflected off of surfaces and is measured in Candelas per square meter (cd/m^2).

Reference
[1] http://academy.autodesk.com/library/building-science/measuring-light-levels
[2] http://www.lighting.philips.com/main/connect/lighting_university/just_in_time_learning_videos_about_lighting/luminous-flux.wpd