Map Service transparency is not honored

Overview:
 

Sometimes a map service that should be transparent is not seen as such. This happens when the viewer is not requesting a PNG32 image format.  PNG8 and GIF format cannot generate semitransparent pixels, so any parts of the image that must be semitransparent will be blended with the map's background color (usually white)

Solution:
 

To resolve this issue, configure your service in Essentials to use the PNG32 output format:

• Open Geocortex Essentials Manager and navigate to the Site you want to configure.
• Go to the Map Services section for that site.
• Click Edit next to the map service you want to modify.
• Select the Display Settings tab.
• In the Image Format dropdown, choose PNG32.