Step 1: Duplicating and Channel Selection
Select "infrared" and move to the channels-palette and select the green channel. This will turn the image black&white.
When having the green channel selected apply the "Gaussian Blur" to it by going to:
Change the blur depending on your picture resolution. My picture is aprox. 4000x2500 so I will put the blur-radius to 20,5 pixels.
Your picture should now be black&white and very blurry.
Change the blend mode to "Screen" on the infrared layer. This will make the picture look sharper.
Step 2: Channel Mixer
In the adjustment layer first check the "monochrome" box then set the following numbers:
Now go back to the "infrared" layer and lower the opacity to around 35%
Step 3: The Noisy Part
Now add a new layer that we will name "grain".
First press the letter D to reset the colors in photoshop. then by blicking Ctrl+Backspace fill the layer with white.
Now we will add noise to the layer.
Go to: filter>noise>add noice...
check uniform and monochromatic and set the amount to 20%
Now your white picture will have a lot of grain in it.
Step 4: All We Need Is Colours
Now were allmost finnished! Now just set the blending opption on the grain layer to multiply and then theres only the colours missing!
If you havent moved the "grain" layer to the top do it now! It's not done in the picture.
To get the colours to the picture, start by once again duplicating the background layer and now dragging it in between the channel mixer and the grain layer. We will name this layer "color".
Now set the blend mode to "Overlay" and the opacity to 50% and youre done!
Congrattulations! You've just made a fake InfraRed photography!