GIMP | Synthwave Style Photo Editing

Video: https://www.youtube.com/watch?v=VmaLSggS6ps

1. Import/open your photo with GIMP
2. Open Colors --> Color Balance...
3. Select the Shadows option and adjust sliders until you notice deep
   purple colors.
4. Select the Midtones option and adjust the sliders until you notice 
   more cyan colors.
5. Select the Highlights option and adjust the Cyan slider down and the
   Yellow slider up until satisfied. Apply.
6. Open Colors --> Color Temperature... and adjust until satisfied.
7. Adjust the brightness and contrast as needed. Most of the time you
   will probably need to decrease the brightness and increase the
   contrast.
8. Use Filters --> Distorts --> Video Degradation and use either the
   Striped or Wide Striped patterns to give the image a CRT TV screen
   look.