there are only one way in YafaRay to get textured-based light emission, in fact this is a pending issue for future versions of YafaRay. The solution is using emit control in a shiny diffuse material with a diffuse texture in Path tracing. For instance, mesh light with a texture won't take the later into account when emiting light. The feature is explained in the last part of the article below:
http://www.yafaray.org/documentation/us ... ffusecolorThe thing is that emit + texture only works as light source in path tracing. It won't work in the other integrators, including DL. However, there are other tricks you can try. For instance, an emit material plus a duplicated mesh working as a portal. However, this trick is not that good, because portal won't take into account the texture applied, unless maybe if you map the same texture on the background. The best and easiest way is using shiny diffuse emit+diffuse texture+path tracing.