检查颜色是否在特定颜色范围内 [英] Checking if a color is in a specific range of colors

问题描述

如何检查rgb或十六进制值是否在特定颜色范围内？最好用ruby。

How would you check if a rgb or hex value is within a specific range of colors? Preferably with ruby.

我使用ruby和rmagick从图像中提取颜色（quantize和color_histogram），然后将这些颜色存储在数据库中。如果有人搜索类似的颜色（hex或rgb），我想要能够返回该颜色。

I'm using ruby and rmagick to extract colors (quantize and color_histogram) from images and then store those colors in the database. If someone searched for a color(hex or rgb) that is similar I want to be able to return that color.

例如。如果有人搜索＃f4f4f4，我想返回＃f5f5f5，＃f3f3f3和所有其他关闭十六进制值。

e.g. If someone searched for #f4f4f4 I'd like to return #f5f5f5, #f3f3f3, and all the other close hex values.

推荐答案

如果将RGB视为三维空间，以R，G和B为轴，则可以将接近颜色定义为颜色周围的立方体或球体，并返回其内部的所有颜色（或检查给定颜色，如果它足够近）。它的形式很简单：

If you treat RGB as a three-dimensional space with R, G and B being the axes, you can define "close colors" as a cube or a sphere around a color and return all the colors inside it (or check for a given color if it's close enough). Formulars for that are quite simple:

Original color R, G, B
Cube with side length L around it:
  All colors between (R - L/2, G - L/2, B - L/2) and (R + L/2, G + L/2, B + L/2)
Sphere with radius R around it:
  New color R_new, G_new, B_new is inside if
    delta_r * delta_r + delta_g * delta_g + delta_b * delta_b < R * R
      where
        delta_r = abs(R - R_new)
        delta_g = abs(G - G_new)
        delta_b = abs(B - B_new)

使用球体而不是多维数据集是正确的方式，但它不会对小的并且立方体内的颜色有点更容易计算。

Using a sphere instead of a cube is the "correct" way, but it won't make much of a difference for small ones and the colors inside the cube are a bit easier to calculate.

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