Arsthbt

Curious to know how this "melting" poster background is created.

Image from unsplash.com

• Increase the canvas vertically from top to bottom:

• Use the Single Row Marquee Tool

to make a selection at the image bottom line of pixels:

• Press Cmd + T Mac or Ctrl + T Win to Transform and scale vertically:

Strech Only Maybe

This can be done in just 5 minutes

==> Select 1 or 2 pixel line from bottom via select tool

==> press ctrl/cmd + t to transform selection.

==> drag below and enter to save your result :)

Hope it helps you :)

I thought it was a bottom selection that was stretched like the other two answers from esteemed users here, but on closer inspection, it is not. There are light lines and dark lines that do not match the image, not at the bottom, and not anywhere else.

So I must (somewhat pedantically) conclude that those lines were achieved by carrying out the "stretching a portion of the image" trick from the other answers to a different, maybe similar image, or else they were hand generated by generating lines on a black background and varying their outer-glow and opacity settings.

In fact the contrast of the "lines" area is quite high, so I think it probably was hand generated.

In the following image I:

1. Created a black background later


2. Made a small square (although that's not important) selection on a new later and filled it white


3. Made more of these white squares fast by control + left click on a white square to select it and then alt left click and drag to create a new matching layer


4. 
   Control + t to make each layer a new random width


5. 
   Control + t to stretch the selections vertically full height


6. Vary the opacity of each layer


7. Apply gaussian blur to the total

Sounds like a lot, but when you know your keyboard shortcuts it was less than a minute of work, of course your example has more detail