If you have ever configured Citrix XenApp\XenDesktop policies you will have noticed that there are settings for TWAIN devices. There are a few official documents from Citrix on how to configure scanning but these guides are quite generic.
There is an official Citrix website you can use to see which Scanners are compatible. Whilst on the face of it this looks like a great idea, when you dig down further you realise that this list isn’t actually a Citrix list of supported scanners,but rather third party companies like HP, Brother etc. testing their scanners with Citrix and then reporting on which ones work. This means if you purchase a scanner from one of these suppliers and it doesn’t work Citrix will not provide support, that is left to the suppliers to best advise, which is not ideal.
There is a great piece of software that will suit most situations and provide a much-needed bridge between the locally attached scanner and the Citrix Session host. The product EACS uses consists of the Workstation and Server parts. The Workstation part should be installed on the local client machine and the Server part goes to the Session Host. As soon as both parts are installed, Scanner for Remote Desktop creates a virtual image scanner via the ICA protocol on the remote side and the operating system detects it as hardware equipment.
Virtual image scanner is actually connected to the locally plugged hardware scanner, so you can access your hardware scanner from any remotely hosted image scanning application. At no point are there any drivers installed on the Session Hosts. This solution also works remotely with WIA applications.