hi , i didnt understand color channels , i watched many videos but i didnt understand channels. for examples red channel meant lines ? what is red , green, blue channels , this is added by photoshop ? And how does ue4 engine matches 6x6 color change on the actor , what is order.
. i see only 6x6 table and colors , but how ue4 matches this colors to actor . really complex
Here is a pretty good explanation (I would recommend you to take a look at the website): ://.com/essentials/rgb/)
“So what’s so special about these three colors, red, green and blue? Well, they just happen to be the primary colors of light. And what does that mean? It means that every color you and I can see is made up of some combination of red, green and blue. How do we get yellow? By mixing red and green. How do we get magenta? By mixing red and blue. What about orange? 100% red, 50% green. And these are just basic examples. Every single color that we can see is made up of some combination of these three colors. Sounds almost impossible, I know, but it’s true.”
So basically you can use those channels in the UE4 to just display the red one and you can even create masks and other stuff in channels so that you dont need a separate texture. The channels aren’t added just by photoshop, it happens with every picture that you make (of course just when the machine uses the RBG colour scheme)
In Photoshop or Gimp you can edit every channel of a texture, and by doing so you can store 3 different black&white textures in a single RGB texture then use them as you see fit(mostly as alpha masks) just like that texture in your post. In game engines this lets you use less memory and less drawcalls, since you’ll be using a single texture which would normally be 3 different textures. You can also use the alpha channel if you want to store a 4th mask in your texture(or a single rgb texture and an alpha mask in the alpha channel)
In the end, as 's post explained those channels represent values and when they are put together as RGB values, you get a diffuse texture(also a picture, photograph, etc.)
All colours in the universe are made up of three primary colours, (channels) - Cyan, Magenta and Yellow, it has nothing to do with Photoshop or Gimp, as mentioned above.
Erm…it has everything to do with Photoshop and Gimp if you are making textures for a game engine, and warchieft was asking about the usage of RGB channels in the material. You dont need to worry about CMY unless you are going to print whatever you make.
What I was trying to say is that colour is a simple phenomenon, and simply put, it boils down to colour being made of three channels, whether it’s for games, photography, art or whatever. So understanding the simple physical nature of the colour spectrum would help this guy. It’s pretty basic stuff!
Yes, and the OP maybe already knows about the basic stuff, but that knowledge doesnt come with the practical knowledge of making use of each channel to store more textures in Photoshop or whichever software you use. I know from myself that i had known the basic stuff before i got into computer graphics but i had to learn how to use the channels of an image file afterwards.
He clearly doesn’t understand the basics of what colour is, “but i didnt understand channels. for examples red channel meant lines ? what is red , green, blue channels”
What you hit on there with masking out channels with different images, is completely different. He didn’t mention that, and if he did, (he could have found many tutorials on YouTube explaining that.
Look at the attachment…it is T_Ceramic_Tile_M from the engine and has 3 different patterns in each channel. That’s why i came to that conclusion. 
Anyway, we both may be wrong so it’s useless to continue this without more input from warchieft.
Touché
in unreal engine 4 tutorial videos , in T_Ceramic_Tile_M map red channels = draw lines on actor , green channels = draw squares on actor , blue channels = draws another squares , they are not used for color , they are used for surface on materials not color ,also in Normal maps red channels and green channels are used for depth and blue channel is surfe , is this a technic for creating surface on actor_? or is all wrong that i wrote?
Textures are made up of 3 or 4 channels. R (red), G (green), B (blue), and optional A (alpha).
In a material you multiply a colour or a texture by each on of these channels and then mix the results together to create a whole new texture that is then applied. In this case the red channel is a mask of lines, the green is a mask of squares etc.
Basically you can use the channels of a texture as black and white masks in your material to modify things another example could be red=metallic and green=roughness. You would connect red to the metallic port and green to roughness. In photoshop you would then paint just in this channels. In red you would paint white for metallic and black for non metallic. In green you would paint white for rough and black for smooth.
The easiest way to understand this is open the the texture I a paint program and look at the channels. Then in the tutorial I assume they show the material being edited. Pause it and see how the lines join up.
Ty for answer black areas = dont paint , white areas = paint ?
If then i multiplied Pink color and T_CobbleStone_Smooth_N =>>>> 
and RESULT = >>
i used alpha channel and alpha channel is totally white and there is no little squares ,but how the result is = little squared i didnt understand , there is no depth in alpha color but result is depthly .
Ty for link , its really usefull
