I'm a bit late, but these are called "Normal Maps" I think.
YOu can create them using this webstie for example : http://cpetry.github.io/NormalMap-Online/
Just drop you image in there and it'll create the normal for you, and there are some options too.

Hippy
View profile on GTA5-Mods.com »
Posts made by Hippy
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RE: How do I retexture game files like sand in photoshop?
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RE: How to create real sounds for cars (SFX) of gta 5
I know I'm a bit late, but I could help you if you want.
I have already made some engine sounds (including a Lambogrghini one).Just join my Discord server so we can talk about it : http://discord.gg/KXkzqBc
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RE: How do i make my custom engine sounds work?
I made some engine sounds if you want to check how they are made.
Are you sure you made the sounds LOUD enough ?
Are they at the correct frequency / compression / length ? -
RE: Jaguar F sport Insane Exhaust
Making engine sounds is possible, just look at the ones I made. But you can't make a custom vehicle sound off of a YouTube video. The .wav files you need to create create have to sound really clear and be a cprecise length, frequency and compression. It's LONG to make a good-sounding sound mod, but it's possible.
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RE: Make a DLC | Add-on with any vehicle easily (video)
Eh beh, ça fait plaisir de voir des vidéos de mdding GTA V en français ! Et c'est super