PHP Color Manipulation

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 tha开发者_高级运维nks!

$newVal = round(round(($rgb['red'] / 0x33)) * 0x33);

In particluar what is the 0x33

Thanks in adavnce

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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).

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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.

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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.

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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.