Pixlr Express is like Instagram on steroids; it's just as free and gives you a host of vintage-style filters to apply, but also comes with so much more.
Don't like the lighting of your shot? Pixlr Express lets you tweak it by applying dramatic lighting effects like coloured shades and fades. If you want to draw the viewer's attention to a certain element of the shot, use focal blur to concentrate the eye.
A dizzying array of effects is available, but once you've worked out your favourites you can save your most flattering overlays. These stay in the app's favourites section for easy filter application on the fly.
We're sure all your friends are beautiful – but could they be more beautiful?
Cymera reckons so, and it's got the smarts to make it happen. Simply take a portrait of your nearest and dearest then apply makeup, new hairstyles and stickers and borders to the photo after the fact. Hours of fun.
When you're not busy prettifying your pals, you can add filters to your snaps, make collages of several pictures and write notes on your photos using the app's various paintbrushes. All for free.
Real life is okay, we suppose, but haven't you ever wished you could live in Springfield or Bedrock or one of those primary-coloured, soft-edged cartoon lands?
If so, Cartoon Camera is the photo app for you and your Samsung GALAXY S4. It takes your harsh real world photos and transforms them into works of cartoon art – choose from bright colours to dark strokes to pencil sketch effects and beyond. There's a free version with ads, or you can shell out 99p for the ad-free app.
If a full on cartoon world isn't your thing, you might want to download the rather more understated Paper Camera.
With a variety of effects ranging from a noir-ish comic book style to the more serious pencil sketch, you can apply the filters as you click or after the fact by choosing any image from your GALAXY S4's gallery.
Each of the filters lets you tweak the contrast and brightness as well as specifying how hard you want the lines to be. Yours for just £1.19.
Polaroid cameras may be dead and gone but their spirit lives on in Polamatic, the official Polaroid app. Shoot photos with your Samsung GALAXY S4 and then turn them into washed-out, nostalgia-tinged Polaroids.
There are a variety of effects and colour options to keep things spicy and you can write captions on the border just like you used to on real Polaroids. Once you're happy with your shots, save them to your GALAXY S4's gallery or share them instantly on Instagram, Facebook, Twitter, Flickr or Tumblr. It'll set you back just 65p.
Free – get it here (or pro edition available to buy for £1.11)
If you want your GALAXY S4 photos to look like they were shot on a professional-grade DSLR, you could do worse than to use AfterFocus.
This clever little app lets you sharpen up the foreground of your images while blurring down the background to give a cool, professional feel. You can be as precise as you like with the smart focus area selection tool, which lets you select the areas you want to be focussed or blurred using the GALAXY S4's touchscreen.
Then you can go mad with film-style effects like Cross Process and apply a romantic out-of-focus bokeh, or blur. There's a free version of the app, or you can invest £1.11 in the pro edition which gives you more filters and the ability to handle higher-resolution images.
If you want to make fun, short looping animated photos then look no further!
Animated Photo is one of our favourite exclusive camera modes on the Samsung GALAXY S4. It lets you create animated GIFs by freezing areas of a photo while allowing other areas to move. And because the Animated Photos you create are GIFs, you can share them easily and quickly with friends and family.
Ask any photographer what image-editing app they use on their GALAXY S4 and they'll tell you Snapseed. It's less about applying filters – although you can do that, with Vintage, Grunge and tilt-shift effects all available – and more about tweaking your shots to perfection.
Whether you opt for auto correct to balance the picture out or you decide to adjust it yourself, there are options from cropping, straightening, brightness and more, so you always have complete control over your photos. The interface is a dream, and the app itself is free.
If you yearn for the days of film photography, Pudding Camera is the next best thing. You still get to use your GALAXY S4, but the app allows you to choose between various "films" that each give a different photographical effect.
You can choose your aspect ratio as well, and apply effects like tilt-shift and fish-eye for added amusement. It's the best of both worlds: old-school film effects paired with the convenience of a powerful smartphone from which you can instantly share your photos.