Changing which Viewer your Browser uses to open a particular file.
For example: Using Mozilla Firefox, visiting morphbank and clicking on a jpg or tif(f) link in morphbank causes the image to open in Microsoft Office Document Imaging software.
To open the images in Photoshop you would click through the following headings: Mozilla Tools> Options> Downloads> Download Actions - View & Edit Actions> Download Actions.
Scroll down to TIF(F) and highlight it, click on "Change Action"
In Change Action box select "Open them with this application" & click on "Browse."
Browse opens a window to allow you to select which program (helper application) will be used to open TIF files when you are browsing. In this example, choose Photoshop.exe and then click on "Open" to associate TIF(F) files with Photoshop. The window will now disappear.
Choose OK in Change Action window
Choose Close in Download Actions window
Choose OK in Options window
REPEAT for JPG files to open in Photoshop as well.