python - 在 PyQt5 中使用 cv2.imshow 和 drawpixmap 的颜色图是不同的

Question

目前，我需要以伪彩色显示我的灰色图像。我使用 opencv2 生成伪色彩图。但是，我发现 cv2 和 QLabel 中显示的颜色图是不同的。

对于 cv2，代码为：

import numpy as np
import cv2

img = np.zeros((256,256),dtype=np.uint8)
img[0:128,0:128] = 255
img[128:255,128:255] = 128
disImg = cv2.applyColorMap(img, cv2.COLORMAP_AUTUMN)
cv2.imshow('test',disImg)
cv2.waitKey()

结果是：

然后，我使用相同的颜色图生成伪彩色图像，并使用drawpixmal显示，代码为：

import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
import numpy as np
import cv2
class MyLabel(QLabel):
    def __init__(self):
        super(MyLabel, self).__init__()
        img = np.zeros((256,256),dtype=np.uint8)
        img[0:128,0:128] = 255
        img[128:255,128:255] = 128
        disImg = cv2.applyColorMap(img, cv2.COLORMAP_AUTUMN)
        QImg = QImage(disImg.data, disImg.shape[1], disImg.shape[0], disImg.strides[0], QImage.Format_RGB888)
        self.qimg = QImg

    def paintEvent(self, QPaintEvent):
        super(MyLabel, self).paintEvent(QPaintEvent)

        pos = QPoint(0, 0)
        source = QRect(0, 0, 256,256)

        painter = QPainter(self)
        painter.drawPixmap(pos, QPixmap.fromImage(self.qimg), source)

class Window(QWidget):
    def __init__(self):
        super(Window, self).__init__()
        layout = QHBoxLayout(self)
        self.resize(300,300)
        self.label = MyLabel()
        layout.addWidget(self.label)


if __name__ == '__main__':

    app = QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())

而且，结果是：

为什么当我显示相同的图像时颜色图不同？

此外， cv2.COLORMAP_AUTUMN 应该是：

因此，cv2 显示的图像是正确的，而 python drawpixmap 显示错误。

如何解决？

标签： pythonopencvpyqtcolormap

Answer 1

感谢 Micka，opencv 使用 BGR，而 qt 使用 RGB 进行渲染。所以，正确的代码应该是：

import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
import numpy as np
import cv2
class MyLabel(QLabel):
    def __init__(self):
        super(MyLabel, self).__init__()
        img = np.zeros((256,256),dtype=np.uint8)
        img[0:128,0:128] = 255
        img[128:255,128:255] = 128
        disImg = cv2.applyColorMap(img, cv2.COLORMAP_AUTUMN)
        b = disImg[:,:,0]
        g = disImg[:,:,1]
        r = disImg[:,:,2]

        img = np.zeros((256,256,3),dtype=np.uint8)
        img[:,:,0] = r
        img[:,:,1] = g
        img[:,:,2] = b
        disImg = img


        QImg = QImage(disImg.data, disImg.shape[1], disImg.shape[0], disImg.strides[0], QImage.Format_RGB888)
        self.qimg = QImg

    def paintEvent(self, QPaintEvent):
        super(MyLabel, self).paintEvent(QPaintEvent)

        pos = QPoint(0, 0)
        source = QRect(0, 0, 256,256)

        painter = QPainter(self)
        painter.drawPixmap(pos, QPixmap.fromImage(self.qimg), source)

class Window(QWidget):
    def __init__(self):
        super(Window, self).__init__()
        layout = QHBoxLayout(self)
        self.resize(300,300)
        self.label = MyLabel()
        layout.addWidget(self.label)


if __name__ == '__main__':

    app = QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())