How to get RGB values of QPixmap or QImage pixel -

问题:

Based on this answer https://stackoverflow.com/a/769221/544721 , I've made following code printing values in grabbed region:

import sys
from PyQt4.QtGui import QPixmap, QApplication
app = QApplication(sys.argv)

# img is QImage type
img = QPixmap.grabWindow(
        QApplication.desktop().winId(),
        x=00,
        y=100,
        height=20,
        width=20,
        ).toImage()

for x in range(0,20):
    for y in range(0,20):
        print( "({},{}) = {}".format( x,y,(img.pixel(x,y)) ) )

But pixels are displayed like this:

(0,0) = 4285163107
(0,1) = 4285163107
(0,2) = 4285163107
(0,3) = 4285163107
(0,4) = 4285163107
(0,5) = 4285163107

How to get RGB values of QImage (obtained from QPixmap) pixels ? (preferably, solution working in 16,24,32 screen bit depths) ?

Example output:

(0,0) = (0,0,0)
...
(10,15) = (127,15,256)

(Solution for Linux, written in Python3)

回答1:

The issue you are seeing is that the number being returned from img.pixel() is actually a QRgb value that is a format independent value. You can then convert it into the proper representation as such:

import sys
from PyQt4.QtGui import QPixmap, QApplication, QColor
app = QApplication(sys.argv)

# img is QImage type
img = QPixmap.grabWindow(
        QApplication.desktop().winId(),
        x=00,
        y=100,
        height=20,
        width=20,
        ).toImage()

for x in range(0,20):
    for y in range(0,20):
        c = img.pixel(x,y)
        colors = QColor(c).getRgbF()
        print "(%s,%s) = %s" % (x, y, colors)

Output

(0,0) = (0.60784313725490191, 0.6588235294117647, 0.70980392156862748, 1.0)
(0,1) = (0.60784313725490191, 0.6588235294117647, 0.70980392156862748, 1.0)
(0,2) = (0.61176470588235299, 0.6588235294117647, 0.71372549019607845, 1.0)
(0,3) = (0.61176470588235299, 0.66274509803921566, 0.71372549019607845, 1.0)

QImage docs:

The color of a pixel can be retrieved by passing its coordinates to the pixel() function. The pixel() function returns the color as a QRgb value indepedent of the image's format.

回答2:

The color components of the QRgb value returned by QImage.pixel can either be extracted directly, or via a QColor object:

>>> from PyQt4 import QtGui
>>> rgb = 4285163107
>>> QtGui.qRed(rgb), QtGui.qGreen(rgb), QtGui.qBlue(rgb)
(106, 102, 99)
>>> QtGui.QColor(rgb).getRgb()[:-1]
(106, 102, 99)