the problem is very simple. Please look at my blender file with 2 cubes and 2 textures.
When exporting as COLLADA, one of the texture (female texture) has its sized reduced to 83ko (>300Ko initially) while the other texture is exported keeping its original size.
Someone suggested that it is because it has embedded color profil but I have tried to change it whitout success.
Enclosed: blender file (and zip with original textures, collada exported files, export settings that I use).
I can send the Photoshop file if necessary.
Texture test.blend (1.09 MB)
Cubes with textures for export.zip (1 MB)