Hello everyone…I’m 16 and I always wanted to create this effect. So I tried to do this with the blender nodes and it came out reliably.
I was so interested to use this super effect which is built-in in cameras nowadays.
Why? Because this effect force viewers to focus on the picture’s or render’s point of interest and it marks out the significance or importance of the particular thing.
So, here is what it does…
This is my brother…OBSERVE EACH IMAGE SEPARATELY…use full-screen view or something…
Edit: Can’t upload pics from the tablet…coming soon with node setup also…Sorry
Guessing game…
Do you want to desaturate everything else but leave a color? Use the keying tool to sample the color you want to leave. Clean up the mask or alpha channel so that it only keys that color. Then reverse the mask and use it to combine the color and black & white images together.
Okay 
Can’t wait for the Pic!!! 
I wanted to desaturate colour and I found a way too…But I am not familiar with keying tools or something…
Show us a screen grab of your node set up then.
You could also just use the Hue Correct node. Go to the “S” tab (saturation), and drag down every point except the color you want to keep.
Doh I just did a tutorial with that tool and forgot all about it.
but mine lets use threshold saturation too…Hype, never thought it was that simple…I went a long way through the math nodes…
I will send the images to Joey via email and he will post it…
Okay, there they are 
I can’t see the images, but a question mark instead…
