以K为单位计算色温 [英] Calculate colour temperature in K

问题描述

我写了一个库来处理颜色，并试图计算 Tc（k）。根据我在。

转换为php，这是什么我到目前为止：

  $ temp = array（9500,7000,5500,3750,3000,2700,2250,1800， 1500）; 
 $ hex = array（'9DBEFF'，'E4EEFF'，'FFE4BE'，'FFA04C'，'FF7A26'，'FF6A19'，'FF500B'，'FF3403'，'FF2300'） 
 
 echo'< h3> K  - > RGB< / h3>'; 
 foreach（$ temp as $ k）{
 $ rgb = ColourConverter :: temperature2rgb（$ k）; 
 echo sprintf（'< div style =background-color：rgb（％s）; text-align：center; width：100px; height：25px; clear：both;>％s< / div ;'，implode（'，'，$ rgb），$ k）; 
} 
 
 echo'< h3> RGB  - > K h 3'; 
 foreach（$ hex as $ v）{
 $ rgb = array_values（ColourConverter :: hex2rgb（$ v））; 
 $ k = round（ColourConverter :: rgb2temperature（$ rgb [0]，$ rgb [1]，$ rgb [2]））; 
 echo sprintf（'< div style =background-color：rgb（％s）; text-align：center; width：100px; height：25px; clear：both;>％s< / div ;'，implode（'，'，$ rgb），$ k）; 
} 
  

我的输出：

很接近但不是100％。 （在我的代码中找到错误，现在几乎完美）

• 颜色稍微偏离k - > rgb


• 它不工作k - > rgb - > k。您不能恢复到相同的值。

代码

UFRaw line〜234

我的php转换

I have written a lib for working with colours and stuck trying to calculate Tc(k). From what I have read working in the CIE 1931 XYZ colour space is the way to go and it can be obtained using xyY.

So far I have got everything correct to the point of figuring out the correct x and y from :

          X                 Y
x = ____________  y = ____________
    ( X + Y + Z)      ( X + Y + Z)

The numbers much up to the chart, but cant find anything that details how you go from x and y to Tc(K)

eg: For #FF0000 I get the following.

x: 0.64007449945677
y: 0.32997051063169

I have read a number of papers on the topic and litterally all the wikipedia articles. All the questions I have come across on SO simply link to a wiki article on colours, not seen one that has the actual formula for calculating Tc(k)

解决方案

I done some digging in some open source apps and found something in UFRaw. I have not quite figured out what is going on exactly.

Also found a paper that seems to cover the topic quite well.

Converted to php and this is what I have so far:

$temp = array(9500, 7000, 5500, 3750, 3000, 2700, 2250, 1800, 1500);
$hex = array('9DBEFF', 'E4EEFF', 'FFE4BE', 'FFA04C', 'FF7A26', 'FF6A19', 'FF500B', 'FF3403', 'FF2300');

echo '<h3>K -> RGB</h3>';
foreach ($temp as $k) {
    $rgb = ColourConverter::temperature2rgb($k);
    echo sprintf('<div style="background-color:rgb(%s); text-align: center; width: 100px; height: 25px; clear: both;">%s</div>', implode(', ', $rgb), $k);
}

echo '<h3>RGB -> K</h3>';
foreach ($hex as $v) {
    $rgb = array_values(ColourConverter::hex2rgb($v));
    $k = round(ColourConverter::rgb2temperature($rgb[0], $rgb[1], $rgb[2]));
    echo sprintf('<div style="background-color:rgb(%s); text-align: center; width: 100px; height: 25px; clear: both;">%s</div>', implode(', ', $rgb), $k);
}

My output:

Pretty close but not 100% yet. (Found a bug in my code and it is now almost perfect)

• The colours are slightly off going from k -> rgb
• It does not work doing k -> rgb -> k. You don't get back to the same value.

Code

UFRaw line ~234

my php conversion

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