Xnsoft's XnView Software · XnRetro (Desktop version) is the cross-platform Free-ware application available for Windows, Linux & even Mac OS X.This application is not an Opensource application.The license simply says that :

"You are granted the right to use and to make an unlimited number of copies of this software, But The software must not be modified, you may not decompile, disassemble."

It's very easy to use this application, just like Instagram. You can even Share the edited image with effects to few social networking websites like Picasa,Flickr,Facebook,Tumblr,Twitpic & few more.The option for share is available under File->Share.

There is also tool in right-side which lets you to increase/decrease various settings like brightness,contrast,saturation,noise,gamma,etc. (same like tools under 'colors' tab in GIMP, but with less features)

Features :
- 20 Retro Effects
- 15 Light Effects
- 5 Vignette Effects
- 28 border Frames

You can download this awesome application from official website : XnView Software · XnRetro (Desktop version)
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[For Linux users] :
Once you download .tgz file, extract it in /home
You will find .desktop file which can be pushed to /usr/share/applications so that it can accessed from Application Dash, but I have found that it doesn't work properly.

So better create XnRetro.desktop manually :

[Desktop Entry]
Type=Application
Name=Xnretro
Exec=sh [Path_Where_Xnretro.sh_is_stored]
Icon=[Path_Where_Icon_is_Stored] (not mandatory)
Terminal=false
StartupNotify=true