[FIXED] How to load a Raw .NEF file into QImage without saving it in Python

Issue

To start things of. I'm new to the image workflow of Python. But I am fairly good at python overall. But i can't seem to find a good solution for displaying RAW .NEF files from a Nikon camera in python. What i want to do is to open the RAW file, convert it to QImage or QPixmap and then display it without saving the image. I have tried libraries such as PIL, rawpy and numpy. But i heard that there is usually an embedded JPEG in the raw files. Is there a neat way to extract that? From what i've found on the internet, people convert the raw file and then save it as a jpeg. But I need to show it without saving it.

with rawpy.imread(file) as raw:
    rgb = raw.postprocess()
rgb = np.transpose(rgb, (1, 0, 2)).copy()
h, w, a = rgb.shape
qim = QtGui.QImage(rgb, w, h, QtGui.QImage.Format_RGB888)

This is what i've been trying now. But that returns None.

fd = file(file_path, 'rb')
# Skip over header + directory
# See manufacture specification
offset = 16  # Magic bytes
offset += 12  # Version
offset += 32  # Camera name
offset += 24  # Directory start & meta
fd.seek(offset, 0)
jpeg_offset = unpack('i', fd.read(4))  # Read where JPEG data starts
jpeg_length = unpack('i', fd.read(4))  # Read size of JPEG data
fd.seek(jpeg_offset[0], 0)
jpg_blob = fd.read(jpeg_length[0])
im = QtGui.QImage(jpg_blob)

This is what i tried to extract the embedded JPEG. But that also return None.

Thank you in advance.

Solution

Using my old answer to convert the numpy image to QImage.

import os
import sys
import rawpy
from PySide import QtCore, QtGui


def read_nef(path):
    image = QtGui.QImage()
    with rawpy.imread(path) as raw:
        src = raw.postprocess()
        h, w, ch = src.shape
        bytesPerLine = ch * w
        buf = src.data.tobytes() # or bytes(src.data)
        image = QtGui.QImage(buf, w, h, bytesPerLine, QtGui.QImage.Format_RGB888)
    return image.copy()


if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)

    w = QtGui.QLabel(scaledContents=True)
    w.resize(640, 480)
    w.show()

    current_dir = os.path.dirname(os.path.realpath(__file__))

    # http://www.luminescentphoto.com/nx2/nefs.html
    filepath = os.path.join(current_dir, "baby.nef")
    image = read_nef(filepath)

    w.setPixmap(QtGui.QPixmap.fromImage(image))
    sys.exit(app.exec_())

Answered By - eyllanesc