Transfering Bitmap Images over a network

Photo by Sora Shimazaki from Pexels

An image is made up of pixels(tiny dots of colours). Images can be stored digitally as bitmaps.

A bitmap (Bit-Map) is a mapping of a domain to bits. In our case, the domain is an array of pixels, here we map a single bit to a pixel.
Pix-map is a map of pixels which maps multiple bits to a pixel.

Bitmaps use the 24bit or 32bit colour depth and use the RGB(255, 255, 255) colour system each of the value in the RGB colour system is stored as a byte(8 bits) an extra 8bits might be used to show transparency of the image

R =8bits
G=8bits
B=8bits #24bit
A=8bits #32bit #extra transparency bit

Storing images in bitmap format will make them very large so images are mostly stored in compressed file format
.PNG:: the lossless compression. It compresses data by using pattern tin pixel colour to reduce the amount of data stored. readmore.
.jpg:: the lossy compression. It compresses data by getting rid o colours that the human eyes will not pick. read more.

Now we are going to write a program to send an image over a network. So we are going to send an image over a network using UDP and we will also use pickle for serialisation

1. Fist of we create a socket sockfd = socket(AF_INET, SOCK_DGRAM)
2. Open the image to be sent image = Image.open("image.png")
3. Get size of the image i.e width and heightwidth, height = image.size
4. Iterate through the whole image (the reason why we have two loops because the image is in a two-dimensional array form)
5. Get RGB value of every pixel in the imagergba = image.getpixel(pos)
6. Change it to a transferable form using “dump” from the pixel module msg = dumps(message)
7. Sending it sockfd.sendto(msg, ("127.0.0.1", 9999))

image we are sending

from socket import *
from pickle import *
from PIL import Image
import time

#create a socket

sockfd = socket(AF_INET, SOCK_DGRAM)

#open image
image = Image.open("100kb.png")

#get image size
width, height = image.size
print(image.size)

for x in range(width):
    for y in range(height):

        #get the position in the two dimensional array
        try:
            pos = (x, y)
            rgba = image.getpixel(pos)

            message = (pos, rgba)
            msg = dumps(message)
            sockfd.sendto(msg, ("127.0.0.1", 9999))
            time.sleep(0.001)
        except:
            print(1)#just a check

1. Now to receive the image…
2. Create a socket
3. Bind socket
4. Create an image file to save data sent image4 = Image.new("RGBA", size=(width, height))
5. Create a function to receive data and write it into the image file

Here I already knew the width and height but we can also send that over the network before we start sending the pixel data

from socket import *
from pickle import *
from PIL import Image 



#viewer = ImageViewer()
sockfd = socket(AF_INET, SOCK_DGRAM)
sockfd.bind(("127.0.0.1", 9999))

height = 170
width = 272
isize = (height, width)
#image = open("image2.png", "x")
image4 = Image.new("RGBA", size=(width, height))
pixels = image4.load()

def get_pixel_data():
    while True:
        msg, cli_addr = sockfd.recvfrom(1024)
        #decoding 
        message = loads(msg)
        pos = message[0]
        rgba = message[1]
        print(pos)
        pixels[pos[0], pos[1]] = rgba
        #print(pixels[pos[0], pos[1]])
        if pos[0] + 1 == width and pos[1] + 1 == height:    
            image4.save("image4.png")
            break
#calling my function
get_pixel_data()

image we received

This was fun to do hope you learnt from my write up, please leave a comment or contact me @black_stroke