skimage将RGB转换为HSV时如何获得正确的颜色。了解色相

Question

我尝试使用skimage将RGB转换为HSV，并得到了我所不期望的行为。这是一些我希望只产生蓝色的示例代码。这一点很重要（以后），因为我想拍摄真实的图像并通过参考色相确定整个图像中每种颜色的数量。

import numpy as np
import skimage as ski
import matplotlib.pyplot as plt

#define my own color in RGB, should be B
tested = np.ones(shape=(100,100,3))*200
tested[:,:,0] =0
tested[:,:,1] =0

hsv_test_img_arr=ski.color.rgb2hsv(tested)

hue_img = hsv_test_img_arr[:, :, 0]
sat_img = hsv_test_img_arr[:, :, 1]
value_img = hsv_test_img_arr[:, :, 2]

fig, (ax1, ax2, ax3) = plt.subplots(ncols=3, figsize=(8, 2))

ax1.imshow(hue_img, cmap='hsv')
ax1.set_title('hue channel')
ax1.axis('off')

ax2.imshow(value_img)
ax2.set_title('value channel')
ax2.axis('off')

ax3.imshow(sat_img)
ax3.set_title('sat channel')
ax3.axis('off')

Answer 1

您忘了正确地规范化数据。所有通道中的值都在0到1之间。因此，您需要将此信息提供给imshow，

imshow(..., vmin=0, vmax=1)

完整代码：

import numpy as np
import skimage as ski
import matplotlib.pyplot as plt

#define my own color in RGB, should be B
tested = np.ones(shape=(100,100,3))*200
tested[:,:,0] =0
tested[:,:,1] =0

hsv_test_img_arr=ski.color.rgb2hsv(tested)

hue_img = hsv_test_img_arr[:, :, 0]
sat_img = hsv_test_img_arr[:, :, 1]
value_img = hsv_test_img_arr[:, :, 2]

fig, (ax1, ax2, ax3) = plt.subplots(ncols=3, figsize=(8, 2))

im1 = ax1.imshow(hue_img, cmap='hsv', vmin=0, vmax=1)
ax1.set_title('hue channel')
ax1.axis('off')
fig.colorbar(im1, ax=ax1)

im2 = ax2.imshow(value_img, cmap="gray", vmin=0, vmax=1)
ax2.set_title('value channel')
ax2.axis('off')
fig.colorbar(im2, ax=ax2)

im3 = ax3.imshow(sat_img, cmap="gray", vmin=0, vmax=1)
ax3.set_title('sat channel')
ax3.axis('off')
fig.colorbar(im3, ax=ax3)

plt.show()

拍摄真实图像会使此操作更加有用。

import skimage as ski
import matplotlib.pyplot as plt

img = "https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/World%2C_administrative_divisions_-_de_-_colored_%28all_countries%29.svg/640px-World%2C_administrative_divisions_-_de_-_colored_%28all_countries%29.svg.png"
tested = plt.imread(img)[:,:,:3]

hsv_test_img_arr=ski.color.rgb2hsv(tested)

hue_img = hsv_test_img_arr[:, :, 0]
sat_img = hsv_test_img_arr[:, :, 1]
value_img = hsv_test_img_arr[:, :, 2]

fig, ((ax0, ax1), (ax2, ax3)) = plt.subplots(ncols=2, nrows=2, figsize=(8, 6))

im0 = ax0.imshow(tested)
ax0.set_title('original')
ax0.axis('off')

im1 = ax1.imshow(hue_img, cmap='hsv', vmin=0, vmax=1)
ax1.set_title('hue channel')
ax1.axis('off')
fig.colorbar(im1, ax=ax1)

im2 = ax2.imshow(value_img, cmap="gray", vmin=0, vmax=1)
ax2.set_title('value channel')
ax2.axis('off')
fig.colorbar(im2, ax=ax2)

im3 = ax3.imshow(sat_img, cmap="gray", vmin=0, vmax=1)
ax3.set_title('sat channel')
ax3.axis('off')
fig.colorbar(im3, ax=ax3)

plt.show()