Hi, thanks for your reply.
I transformed every tif to jpg but still the same problem that colors are not imported. I now tried several files and I am confused because for some the colors are imported and for some they are not. But I can not figure out what the difference between these files are.
Is there anything I should pay attention to when downloading files?

Hi,

@okh, well seen !

Here is an example :
Name of the object = object

The zipped package contains 3 objects (made recently) :
object.mtl
object.obj
object_cylinder.jpeg

The beginning of the 'object.obj' is like this :
#
# Generated by Sweet Home 3D - ven. mai 19 15:08:29 CEST 2017
# http://www.sweethome3d.com/
#
mtllib object.mtl
g cylinder_1
usemtl cylinder
v 0.0000004 240.00002 -15.000001
...

The beginning of the 'object.mtl' is like this :
#
# Generated by Sweet Home 3D - ven. mai 19 15:08:29 CEST 2017
# http://www.sweethome3d.com/
#

newmtl cylinder
illum 1
Ka 0.2 0.2 0.2
Kd 1.0 1.0 1.0
Ks 0.0 0.0 0.0
Ns 1.0
map_Kd object_cylinder.jpeg

The name of the used texture is :
object_cylinder.jpeg (or jpg)

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