Add open with custom application to context menu

i have a picture viewing app. i want the context menus of JPG,PNG and other IMAGE files to have "View using (custom App)" how do we do this.
i went to the registry found JPG and PNGfiles key. i created a key under shell key in these.named"View using Custo app". And command i set the value as "(the locaton)%1"
but nothing. but when i did this with the "*" key in class root. it worked but the the "view with Custo app" entry appears in every file i want it to be in only image files not other files.

Open With Context Menu Item - Add or Remove

Perhaps these links will help you customize your context menu just the way you wish to:

Customize the Right Click Menu in Windows 7 - Make Tech Easier

Edit Context Menu Items In Windows 7 & Vista – from the WinVista Club site

FileMenu Tools allows you to customize the context Menu of Windows Explorer, including:
Add some built-in utilities that perform operations on files and folders.
Add customized commands which run external applications, copy or move to a specific folder, or delete specific file types.
Configure the "Send to..." sub-menu.
Enable or disable commands which are added by other applications to the context menu.