I'm having a recurring problem with exporting raster imagery in QGIS's print composer for use in CorelDraw X7 (for map styling). The problem has persisted for some time, through many releases of QGIS (now on 2.18.16; Windows 10).
Maps will appear as expected in print composer, and the exported image appears as expected in Adobe Acrobat Reader DC. In CorelDraw X7, however, some raster images in the PDF will appear as either black or white, though any vector items appear normally. Examples of rasters with this problem include both high resolution orthoimagery, as well as scanned and geo-referenced maps.
This problem is sometimes fixed by generating a new PDF from print composer. Where this solution works, differences between PDF's that load as expected in CorelDraw X7 and those that do not typically consist of small (a few hundred kilobyte) differences in file size.
"Export as Image" results work as expected.
Looking for some help to figure out what is causing this problem in order to allow for map production workflow where layers are preserved in CorelDraw.