My Entry for the Let's Make A Collage - Arts & Science

Hey everyone,

Today, it's not an article about a STEM topic, or is it? What would you do if you had to make a collage about dark matter ? (Try to read that again with Michael's voice from Vscauce ;) )

You can find more information about the contest here.

We will go straight to the point, here is my entry :

I hear you, I know, this look a lot like the picture we had to start with :

[Credits: Jeremy Thomas (public domain)]

But here is the thing, dark matter is not visible (yet, to our detectors) and so is my collage, at least not visible to the naked and untrained eyes. Try to look closer, zoom in.

Do you see it now ? For my entry, I created a program to hide (very badly) my collage inside the image we had to start with. I say very badly because you can notice it very easily, as 8 out of 9 pixels are from the template and 1 in 9 pixels are from the hidden image :

Really zoomed in screenshot of the entry where you can see a big difference between the colors of the pixels from the 2 images

You can easily see what the hidden image is with a big enough screen, but I still consider this to be some sort of steganography, meaning hiding messages inside another content (text, image, audio, anything you want). I love the idea of hiding things in plain sight! This kind of cryptography is a fascinating world, perhaps as much as the cosmos and everything that surround our Pale Blue Dot, including Dark Matter.

And here is the image I tried to hide, just 2 robots having a blast on the accretion disk of a black hole :

The collage hidden

Here is the Python program I wrote to create the entry :

import cv2 as cv # I used the OpenCV module
#We load the images in the program
source = cv.imread("0.jpeg") #The one we had to start with
collage = cv.imread("1.jpeg") #The collage I want to hide
#We get the dimensions of the image (I crop them to the same dimensions before hand)
[h,w,c] = source.shape #Height, Width, Number of canals
result = source #Copy source in result
#Change the value of the pixels based on their positions
for y in range(h):
for x in range(w):
if y%3==0: #1 in 3 pixels vertically
if x%3==0: #1 in 3 pixels horizontally
result[y,x] = collage[y,x] #Replace the pixel with the value of the same pixel in the collage
#Show the result
cv.imshow("Result",result)
cv.waitKey(0) #Wait for a key to be pressed to continue
#Save the result in file
cv.imwrite("result.jpeg",result)

So I know this entry is a little meta, and I'm not an artist of any sort, but I liked the idea and had to submit it. I hope you enjoyed this post !

See you soon !

PS : Here you can see just the pixels from the hidden image :