PHP 颜色操作
我目前正在研究颜色操作/选择等，并遇到了以下代码。我想知道有人可以告诉我下面的代码是做什么的，并为我分解它，谢谢！
$newVal = round(round(($rgb['red'] / 0x33)) * 0x33);
特别是 0x33 是什么
提前致谢
I am currently looking into color manipulation / selection etc and have come across the following piece of code. I was wondering of someone could tell me what the following piece of code is doing and break it down for me thanks!
$newVal = round(round(($rgb['red'] / 0x33)) * 0x33);
In particluar what is the 0x33
Thanks in adavnce
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它似乎正在将 $rgb['red'] 转换为最接近的 0x33 倍数。
它可能会这样做，因此颜色最终会出现在所谓的“网络安全”调色板上，该调色板（如果我没记错的话）由 RGB 值是 0x33 倍数的颜色组成。
0x33 是 51（十进制）的以 16 为基数（十六进制）表示。
It seems to be converting
$rgb['red']the nearest multiple of 0x33.It's probably doing that so the color will end up on the so-called "web safe" color palette, which (if I recall correctly) consists of colors who's rgb values are multiples of 0x33.
0x33 is the base-16 (hex) representation of 51 (decimal).
0x33 是 51，因此它将单个字节的 0-255 值缩放为 0-5，然后再缩放回来。这会导致该值被下限为低于该值 51 的最高倍数。
0x33 is 51, so it scales the 0-255 value of a single byte to 0-5, and then scales it back out. This results in the value being floored to the highest multiple of 51 lower than the value.
0x33 只是 33 的十六进制值。
我不太确定发生了什么，但我猜测它会计算任何颜色的网络安全十六进制。或者类似的东西。
0x33 is just hex value for 33.
I'm not really sure what is happening, but my guess would be it calculates a web safe hex of any color. Or something along these lines.
正如@Seth 所指出的，它将颜色舍入到最接近的“网络安全”颜色。这是一个古老的想法，可以追溯到大多数彩色显示器都是 8 位的时候。 Visibone 是使其流行的人之一，因为他们的“网络安全色卡”是他们的第一个产品。
有关详细信息，请参阅网页颜色。
As @Seth indicated, it's rounding colours to the nearest 'web-safe' colour. It's an old idea, dating from back when most colour displays were 8-bit. One of the people to make it popular was Visibone as their 'websafe colour chart' was their first product.
See Web Colours for more information.