Please note: Atalasoft Support strongly recommends avoiding storing Atalasoft assemblies in the GAC, and instead recommends placing the needed dlls in the bin directory of the application. If you absolutely must store our assemblies in the GAC, this is how to do it:
If you want to deploy Atalasoft assemblies in the GAC for a web project using our legacy controls (WebAnnotationViewer, WebImageViewer, WebThumbnailViewer... but NOT our newer HTML 5 controls WebDocumentViewer, WebDocumentThumbnailer), you need to change the registration directives at the top of your .ASPX files to include the exact version and public key that you want to load.
They should look something like this
<%@ Register TagPrefix="cc1" Namespace="Atalasoft.Imaging.WebControls" Assembly="Atalasoft.dotImage.WebControls, Version=10.x.x.x, Culture=neutral, PublicKeyToken=" %>
The Version should be set to the exact version you need and the PublicKeyToken should be set to the public key token for the assembly as well. The GAC lists both of these values for the assembly. Open up a windows explorer and point it at C:\WINDOWS\assembly, and look for the assembly that you want to refer to in the directive above.
NOTE: DotImage 10.3 and newer corrected some long standing issues with our Atalasoft.Shared.dll not having unique properties which were interfering with GAC deployment. If you MUST use the GAC, be sure you're using at least 10.3 (but 11.1 is the current version as of February 2019)