如何使用 OpenCV-Python 更改某個區域的色調

Question

我想編輯某個區域的hsv值我想改變顏色的圖片

我將圖像的所有紫色部分更改為綠色。 這是我在圖像編輯軟件中制作的結果，只是為了展示一個例子。 結果是的，我無緣無故地讓它變黑了，但我只想讓刀片變綠而不是手柄

Answer 1

Python/OpenCV 中的簡單方法是使用 inRange() 創建圖像為紫色的蒙版，然后使用 Numpy 將蒙版為白色的圖像更改為綠色。

輸入：

import cv2
import numpy as np

# load image with alpha channel
img = cv2.imread('sword_purple.png', cv2.IMREAD_UNCHANGED)

# extract alpha channel
alpha = img[:,:,3]

# extract bgr channels
bgr = img[:,:,0:3]

# select purple
lower_purple = (140,40,110)
upper_purple = (170,60,130)
mask = cv2.inRange(bgr, lower_purple, upper_purple)

# change the image to make it green where the mask is white
bgr_new = bgr.copy()
bgr_new[mask==255] = (0,255,0)

# put alpha back into rgb_new
bgra = cv2.cvtColor(bgr_new, cv2.COLOR_BGR2BGRA)
bgra[:,:,3] = alpha

# save output
cv2.imwrite('sword_alpha.png', alpha)
cv2.imwrite('sword_bgr.png', bgr)
cv2.imwrite('sword_mask.png', mask)
cv2.imwrite('sword_masked_green.png', bgr_new)
cv2.imwrite('sword_green.png', bgra)

# Display various images to see the steps
cv2.imshow('alpha',alpha)
cv2.imshow('mask',mask)
cv2.imshow('bgr_new',bgr_new)
cv2.imshow('bgra',bgra)
cv2.waitKey(0)
cv2.destroyAllWindows()

阿爾法通道：

BGR 渠道：

面具：

重新着色的 BGR 通道：

放回 alpha 通道的結果：

或者，您可以通過將 BGR 轉換為 HSV 並以相同的方式將紫色更改為綠色來執行相同的操作。 然后轉換回 BGR 並放回 alpha 通道。

Answer 2

這是一種在 Python/OpenCV 中通過改變色調來做到這一點的方法。

輸入：

import cv2
import numpy as np

# load image with alpha channel
img = cv2.imread('sword_purple.png', cv2.IMREAD_UNCHANGED)

# extract alpha channel
alpha = img[:,:,3]

# extract bgr channels
bgr = img[:,:,0:3]

# convert to HSV
hsv = cv2.cvtColor(bgr, cv2.COLOR_BGR2HSV)
#h = hsv[:,:,0]
#s = hsv[:,:,1]
#v = hsv[:,:,2]
h,s,v = cv2.split(hsv)

# purple is 276 in range 0 to 360; so half in OpenCV
# green is 120 in range 0 to 360; so half in OpenCV
purple = 138
green = 60

# diff color (green - hue)
diff_color = green - purple

# modify hue channel by adding difference and modulo 180
hnew = np.mod(h + diff_color, 180).astype(np.uint8)

# recombine channels
hsv_new = cv2.merge([hnew,s,v])

# convert back to bgr
bgr_new = cv2.cvtColor(hsv_new, cv2.COLOR_HSV2BGR)

# put alpha back into bgr_new
bgra = cv2.cvtColor(bgr_new, cv2.COLOR_BGR2BGRA)
bgra[:,:,3] = alpha

# save output
cv2.imwrite('sword_alpha.png', alpha)
cv2.imwrite('sword_bgr.png', bgr)
cv2.imwrite('sword_bgr_new.png', bgr_new)
cv2.imwrite('sword_green.png', bgra)

# Display various images to see the steps
cv2.imshow('alpha',alpha)
cv2.imshow('bgr',bgr)
cv2.imshow('bgr_new',bgr_new)
cv2.imshow('bgra',bgra)
cv2.waitKey(0)
cv2.destroyAllWindows()

結果：