RGB和HSV空间之间的转换 [英] conversion between RGB and HSV space

问题描述

我目前正在尝试使用 rgb2hsv 函数将两个对象从RGB空间转换为HSV空间，一个是图像，另一个是RGB值矩阵，但是我对矩阵值部分的结果不一致。

I am currently trying to convert two objects from RGB space to HSV space using the rgb2hsv function, one being an image, the other being a matrix of RGB values, but my results for the value part of the matrix are not consistent.

矩阵 I 中的值的结果在1到255之间，但在第二个矩阵<$ c $中c> D ，它们介于0和1之间。有人知道为什么会这样吗？

The results for value in matrix I are between 1 and 255, but in the second matrix D, they are between 0 and 1. Does anybody know why this is the case?

I = imread('00000001.jpg');
I = rgb2hsv(I);

D = [221 12 26; 30 68 76; 40 47 27; 165 87 25; 37 59 26; 148 125 91];
D = rgb2hsv(D);

推荐答案

当你打电话给 rgb2hsv ， N -by-3 矩阵，将解释为色彩图，而不是图像甚至图像强度。色彩图的值为[0,1]，而 uint8 图像的值为[0,255]。这就是 rgb2hsv 所期望的。

When you call rgb2hsv with a N-by-3 matrix, it is interpreted as a colormap, not an image or even image intensities. A colormap has values on [0,1], while a uint8 image has values on [0,255]. This is what rgb2hsv expects.

rgb2hsv帮助页面解释的colormap语法：

H = rgb2hsv（M）转换RGB颜色映射到HSV颜色映射。
每个地图都是一个矩阵，包含任意数量的行，正好是三列，
和0到1之间的元素。

H = rgb2hsv(M) converts an RGB color map to an HSV color map. Each map is a matrix with any number of rows, exactly three columns, and elements in the interval 0 to 1.

运行 D = rgb2hsv（D）; 时，它使用上述语法运行它，而不是将输入视为图像。

When you run D = rgb2hsv(D); it is running it with the above syntax, rather than treating the input as an image.

也就是说，您可以将输出的第三列 D 除以255，因为生成的奇异色图似乎只是缩放了价值元素。

That said, you can just divide the third column of the output D by 255 since the resulting bizarro colormap seems to simply have scaled value elements.

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