Here's an image of what I mean. It was grabbed from displaying the two county images in QGIS rather than programmatically generated by a MapSuite program. I'll start creating a sample MapSuite program to generate a similar map, but the issue should be evident from this image... Images are rectangular, counties are not, therefore there is a part of the rectangular image for each county that is black representing areas without data. If the black is displayed then it obscures some of the adjacent image.
If wanting the actual data I used, it is large (too large to attach here I believe), but is freely
available from the NRCS GeoSpatial Data Gateway
Click on GET Data
Select "Kentucky" as the state
Select Counties "Clark" and "Madison" and click the "Submit Selected Counties" button
Choose the "2012 National Ag. Imagery Program Mosaic, 2 maps 706.632 MB" option and then click the "CONTINUE" button
Leave "FTP" as the delivery method and click "CONTINUE"
Enter your contact info and click "CONTINUE"
Click "PLACE ORDER"
You'll then receive an email in a few minutes that contains a link to use to download the data.