binary data to image raw python

It is better to debug these problems when both the code for server as well the client are fully given (but simplified to just show the problem).

So, following is a very basic client based on your initial code and description. Note that image_type isn't used, it is just there because you mentioned you wanted to differentiate between JPEG and RAW. I always assume the received data is RGB data, you can adapt this to your actual problem. The main difference here is the use of struct, which is a standard way to pack data in a common format to send over network and avoid problems related to byte ordering. This code also expects to receive the image width and height (which was not present in your code), so you can reconstruct the image in the client.

import socket
import struct
from PIL import Image

def recv(sock, size):
    data = ''
    to_receive = size
    while to_receive > 0:
        data += sock.recv(size)
        to_receive = size - len(data)
    return data

serv_host = ''
serv_port = 5003

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((serv_host, serv_port))

s.settimeout(1)

image_type = struct.unpack('!b', recv(s, 1))[0]
print "Image type: %d" % image_type
image_size = struct.unpack('!i', recv(s, 4))[0]
print "Image size: %d" % image_size
image_width, image_height = struct.unpack('!hh', recv(s, 4))
print "Image dimensions: %d x %d" % (image_width, image_height)

# Receive image data
image_data = recv(s, image_size)
print len(image_data)

# When we receive the image, we send the acknowledgement.
s.send('OK')
s.close()

img = Image.fromstring('RGB', (image_width, image_height), image_data)
img.save('out.png')

Since the server was not included, following is a simple one that respects the protocol you described. I did not bother checking for fully received data in the server. Also note that this server only serves a single image that is specified in the command line when you run it. Again, adapt for your problem. Also observe that I'm not sending the image mode, which may be a problem in the actual application.

import sys
import socket
import struct
from PIL import Image

host = ''
port = 5003
backlog = 5

serv_img = Image.open(sys.argv[1])
simg_size = serv_img.size
serv_data = serv_img.tostring()
data_size = len(serv_data)

print "Serving data of size %d" % data_size

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))
s.listen(backlog)
while True:
    client, address = s.accept()

    client.sendall(struct.pack('!b', 1))
    client.sendall(struct.pack('!i', data_size))
    client.sendall(struct.pack('!hh', *simg_size))
    client.sendall(serv_data)

    data = client.recv(2)
    if data == 'OK':
        print "OK", address

    client.close()

The raised note about not using __len__ is simply due to it being a special method in Python, which is called by len itself. If you don't have any good reason to use special methods, then don't do it.

You mentioned using the image server from USARSim. Here's the code I'm using to receive images from USARSim (UT2004 version):

def get_image(sock):    
    image_type = struct.unpack('b', sock.recv(1))[0]    
    image_size = struct.unpack('>i', sock.recv(4))[0]

    if image_size < 250000:      
        image_data = ""
        received = 0
        while (received < image_size):
            data = sock.recv(image_size-received)
            received += len(data)
            image_data += data        

        filename = "image_%s.jpg" % str(now())
        with open(filename, "wb") as f:
            f.write(image_data)

def write_ack(sock):
    sock.send("OK")

def main():
   sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   sock.connect((host, port))

   while True:
       get_image(sock)
       write_ack(sock)