I would like to export a georeferenced tif from QGIS composer. I am using QGIS 2.16.1 with windows 7 (32 bit).
In the composer export settings I have selected "Print as raster" and "Save World File". I am using an export resolution of 96 dpi and an A4 page size. When I use "Export as image" and use file formats including jpg, tif, tiff and bmp I obtain excellent raster images without a corresponding world file. The QGIS documentation states that the "Exporting big rasters can sometimes fail, ..." but does not qualify what big means, or, what is meant by "fail".
In my situation a suitable raster is generated, but, it is missing the associated world file. My data is a topographic map containing vector layers only. Although the generated image file is not accompanied by a world file, it contains the suitable "Layer Spatial Reference System" property, but is missing the "Pixel Size" and "Origin" properties. From the same QGIS project file and the same "print composer" QGIS 2.14.3 outputs an image file that contains the suitable "Pixel Size" and "Origin" properties.