将多类分割灰度标签图转RGB三通道图

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---------Start

灰度标签图：

0,1,2,3,4分别代表：background,car,wheel,lights,window五个类别。显示全黑。

代码：

prediction代表读入的标签numpy数组（灰度图读入）

		prediction = cv.imread('test.png',flag=0)
        a1 = copy.deepcopy(prediction)
        a2 = copy.deepcopy(prediction)
        a3 = copy.deepcopy(prediction)

        a1[a1 == 1] = 255
        a1[a1 == 2] = 0
        a1[a1 == 3] = 255
        a1[a1 == 4] = 20

        a2[a2 == 1] = 255
        a2[a2 == 2] = 255
        a2[a2 == 3] = 0
        a2[a2 == 4] = 10

        a3[a3 == 1] = 255
        a3[a3 == 2] = 77
        a3[a3 == 3] = 0
        a3[a3 == 4] = 120

        a1 = Image.fromarray(np.uint8(a1)).convert('L')
        a2 = Image.fromarray(np.uint8(a2)).convert('L')
        a3 = Image.fromarray(np.uint8(a3)).convert('L')
        prediction = Image.merge('RGB', [a1, a2, a3])
        prediction.save('test2.png')

转换的RGB图片：

通过手动设置三通道的RGB值，实现（0,1,2,3,4）到五种RGB颜色的转换。

至此，设置完毕！