Edge padding research

Edge padding
When a game model uses a single texture sheet (Texture atlas) the image will have areas that are used for the textures and blank areas between them. The used areas are often called UV shells, and the blank areas are often called gutters.
When a game engine renders a scene it uses Texture filtering to smoothly render the texture, in a process called downsampling. If the gutters have colors that are significantly different from the colors inside the shells, then those colors can "bleed" creating seams on the model. The same thing happens when neighboring shells have different colors; as the texture is downsampled eventually those colors start to mix.
To avoid this, edge padding should be added in the gutters between each UV shell. Edge padding duplicates the pixels along the inside of the UV edge and spreads those colors outward, forming a skirt of similar colors.
When the UV layout is created, the spacing between the shells should be done with edge padding in mind. If the gutters between the UV shells aren't wide enough, there won't be enough edge padding to prevent bleeding.

All information obtained from - (Wiki.polycount.com)