python string and Qt string (QString)

To convert from python string to QString:

                     Qt_string = QtCore.QString(python_string)

To convert from QString to python string:

                    python_string = str(Qt_string)

QPixmap, QBitmap and QImage

QPixmap is not the only image class PyQt offers: there's also QBitmap, which is just like QPixmap, but for black and white images only, and QImage. Where QPixmap and QBitmap are optimized for drawing (and then showing on screen or on a printer), QImage is optimized for reading and writing (together with the QImageIO class), and for manipulating the actual pixels of an image. There's another image-related class, QPicture, which can be used to record drawing operations and replay them later. The recorded paint events can then be stored in a file and reloaded later on. Those files are called meta-files — but they're in a special Qt format. In Qt 3, QPicture also supports the standard scalable vector graphics format, svg. If you want to create a complex vector-drawing application you'd be well advised to stick to this standard.

Setting rectangle to choose crop area

def mousePressEvent(self, event):
        self.rbOrigin = self.mapFromGlobal(event.globalPos())
        self.rubberBand.setGeometry(QtCore.QRect(self.rbOrigin, QtCore.QSize()))
        self.rubberBand.show()
        self.x1 = int(QtCore.QPoint.x(self.rbOrigin))
        self.y1 = int(QtCore.QPoint.y(self.rbOrigin))
        print self.x1
        print self.y1

def mouseMoveEvent ( self, event ) :
        self.x2 = int(QtCore.QPoint.x(self.mapFromGlobal(event.globalPos())))
        self.y2 = int(QtCore.QPoint.y(self.mapFromGlobal(event.globalPos())))
        self.x = self.x2 - self.x1
        self.y = self.y2 - self.y1
       
        if (self.x == 0):
            self.x = 4*self.y
        else:
            self.y = self.x/4
        self.x2 = self.x + self.x1
        self.y2 = self.y + self.y1
               
        self.rubberBand.setGeometry(QtCore.QRect(QtCore.QPoint(self.x1, self.y1), QtCore.QPoint(self.x2, self.y2)).normalized())
       

converting pixmap image to qimage

        qimage = QtGui.QPixmap.toImage(self.pixmap)

Converting from qimage to pil image

 buffer = QtCore.QBuffer()
 buffer.open(QtCore.QIODevice.ReadWrite)
 self.qimage.save(buffer, "JPG")

 strio = cStringIO.StringIO()
 strio.write(buffer.data())
 buffer.close()
 strio.seek(0)
 pil_img = Image.open(strio)

Resize image in opencv

from opencv.cv import *
from opencv.highgui import *



if __name__ == '__main__':
   
   
    ipl = cvLoadImage("/home/selva/Desktop/me.jpg");
    newImage = cvCreateImage(cvSize(48, 16), ipl.depth, ipl.nChannels);
    cvResize(ipl, newImage, CV_INTER_LINEAR);

    cvNamedWindow("image pop", CV_WINDOW_AUTOSIZE)
    cvShowImage("image pop",newImage)
    cvWaitKey()

crop image in opencv

from opencv.cv import *
from opencv.highgui import *


if __name__ == '__main__':
   
    new_width = 120
    new_height = 110
    ipl = cvLoadImage("/home/selva/Desktop/me.jpg");
    cropped = cvCreateImage( cvSize(new_width, new_height), 8, 3)
    src_region = cvGetSubRect(ipl, cvRect(110, 120, new_width, new_height) )
    cvCopy(src_region, cropped)

   
    cvNamedWindow("image pop", CV_WINDOW_AUTOSIZE)
    cvShowImage("image pop",cropped)
    cvWaitKey()

Opening Qt loaded file in PIL

fileName = QtGui.QFileDialog.getOpenFileName(self, self.tr("Open File"),
                                                     QtCore.QDir.currentPath())
pil_img = self.setImage(str(fileName))

def setImage(self, filename):
        "set image to given filename"
        self.filename = filename
        self.pilImg = None
        if not (filename and os.path.exists(filename)):
            return
        
        try:
            pilImg = Image.open(filename)
        except IOError:
            self.writeStatus("Error loading image")
            return
        return pilImg

PIL to Qimage converter

import sys
from PyQt4 import QtGui
from PIL import Image
from opencv import adaptors
from opencv import cv

def get_image(w, h):
    clr = chr(0)+chr(255)+chr(0)
    pil_img = Image.open("/home/selva/Desktop/me.jpg")
    ipl_img = adaptors.PIL2Ipl(pil_img)
    #after process in opencv
    pil_img2 = adaptors.Ipl2PIL(ipl_img)
    return pil_img2

def pil2qpixmap(pil_image):
    w, h = pil_image.size
    data = pil_image.tostring("raw", "BGRX")
    qimage = QtGui.QImage(data, w, h, QtGui.QImage.Format_RGB32)
    qpixmap = QtGui.QPixmap(w,h)
    pix = QtGui.QPixmap.fromImage(qimage)
    return pix

class ImageLabel(QtGui.QLabel):
    def __init__(self, parent=None):
        QtGui.QLabel.__init__(self, parent)

        self.setGeometry(300, 300, 550, 550)
        self.setWindowTitle('Window')
               
        self.pix = pil2qpixmap(get_image(50,50))
        self.setPixmap(self.pix)



app = QtGui.QApplication(sys.argv)
ImageLabel = ImageLabel()
ImageLabel.show()
sys.exit(app.exec_())

PIL to IPL and IPL to PIL converters

# use OpenCV-2.0.0 and later

from opencv.cv import *
from opencv import adaptors
from opencv.highgui import *
from PIL import Image

if __name__ == '__main__':
    pil_img = Image.open('/home/selva/Desktop/me.jpg')

    cv_img = adaptors.PIL2Ipl(pil_img)

    cvNamedWindow("pil2ipl")
    cvShowImage("pil2ipl", cv_img)
    cvWaitKey()