export to OBJ file

I am trying export cube with UV map to .obj file, but can not find in .mtl file link to .png picture…
what I need to do to get ling to picture in .mtl file?

Here (from in BI created material) export creates 2 files:


cube.obj
===============================================%<
# Blender v2.70 (sub 1) OBJ File: 'cube.blend'
# www.blender.org
mtllib cube.mtl
o Cube
v 1.000000 -1.000000 -1.000000
v 1.000000 -1.000000 1.000000
v -1.000000 -1.000000 1.000000
v -1.000000 -1.000000 -1.000000
v 1.000000 1.000000 -0.999999
v 0.999999 1.000000 1.000001
v -1.000000 1.000000 1.000000
v -1.000000 1.000000 -1.000000
vt 0.000000 0.000000
vt 1.000000 0.000000
vt 1.000000 1.000000
vt 0.000000 1.000000
usemtl Material
s off
f 1/1 2/2 3/3 4/4
f 5/1 8/2 7/3 6/4
f 1/1 5/2 6/3 2/4
f 2/1 6/2 7/3 3/4
f 3/1 7/2 8/3 4/4
f 5/1 1/2 4/3 8/4
%<===============================================%<

cube.mtl

%<================================================%<
# Blender MTL File: 'cube.blend'
# Material Count: 1

newmtl Material
Ns 96.078431
Ka 0.000000 0.000000 0.000000
Kd 0.640000 0.640000 0.640000
Ks 0.500000 0.500000 0.500000
Ni 1.000000
d 1.000000
illum 2
map_Kd osb.jpg

Include UVs and Write Materials are options needed.
If Path Mode is set to Copy texture files are written out.

Edit: cycles material does the same export; last line in mtl is path to texture file and Path Options set how that will be exported - Relative, Absolute and so on.

I found that Blender Render and Blender Game creates path to picture file but Cycles does not create

I have this problem too, after saving the texture as a png and exporting an obj, I still have to edit the mtl file, adding the line map_Kd [texture].png