The Brackets 1.14.2 release brings in a new enhancement which enables you to open any arbitrary file type with external applications. In User Preferences settings, you can associate a file extension to open with the system default associated application or open with a specific application.
You can add/modify/delete the file type associations by going to “Debug->Open Preferences File” menu and editing the preference “externalApplications”.
Here are the possible values for file type associations:
On opening a folder which has graphic file types, for the first time you will be prompted with option to associate graphic file types: .psd, .jpg, .ai, .svg, .png, .xd with their default applications (feature reference workflow). Once the association is saved in Brackets preferences, you will be able to double click & open these files types in their associated applications.