The problem with filters in many photo editors is that you're required to apply them to the whole image, or spend an age creating precise selections. Repix lets you 'paint' filter effects onto your images to create brilliant effects.
A choice of nine brushes run along the bottom of the screen; they range from artistic effects such as Posterize and Charcoal to more creative effects such as Halftone patterns and Ink splats. There's also an eraser and an 'undoer' brush.
We're huge fans of online portfolio platform Behance at Creative Bloq, especially this super-slick iPhone app. It offers many of the perks enjoyed by users of the online version, including the ability to search millions of projects and follow top creatives.
Users can also access their personal profile and collections and view stats about their work, all on the go, all for free.
18. Autodesk SketchBook
SketchBook Pro by Autodesk is one of the most popular iPad art apps with digital artists. The smaller-screen version is a brilliant addition to any designer's iPhone app collection.
There's a wide range of digital pencils, pens, markers and airbrushes to choose from (over 170 customisable brushes in total), all accessed via a simple but intuitive UI that lets you pin toolbars to the screen for easy access. You can work with layers, transparency options, annotations, and advanced blend modes. What more could you want?
Gradients have become a lost art in iPhone photography, but Geló fills that gap in the market well. Once you've taken or imported an image, you see a carousel of 'gels'. Cycle through to choose a colour, tap it, and then it's applied to your shot. You can then use the sliders to tweak how the filter affects your shot, and it's this high level of control that makes Geló a winner.
You can adjust individual colours and the position of the effect until it gives you a realistic graduation (usually for a horizon), or you can get a bit arty and create vintage looks or use different shapes to add a 'gel collage' effect.
You can also choose how the gel effect is applied, either a tint, a solid gel (Over) or mixed into the colour palette (Add). Coupled with contrast tweaks, you can create impressive images.
Evernote allows you to save your ideas, things you like, things you hear and things you see. You can access your inspiration anywhere as it works with nearly every computer, phone and mobile device out there. And to make things easier, you can search by keyword, tag, or even printed and handwritten text inside images.
Chances are, you don't need an introduction to this app. Instagram is a wildly popular photo-sharing app that enables its community (currently over 500 million-strong) to take pictures, apply digital filters to them, and share them on a variety of social networking services.
Used right, it can be a great source of design inspiration – check out these amazing illustrators of Instagram, graphic designers on Instagram, typography accounts on Instagram, and fantasy artists on Instagram, for example.
22. OmniFocus 2
Having scooped the Apple Design Award for best productivity app when the iPhone App Store first launched, OmniFocus has continued to develop and packs plenty of features into its simple, intuitive interface.
The app is free to download and trial, but there's a high price tag of $39.99/£38.99 to unlock the standard services. Despite this, it's invaluable for organising all your daily tasks in one place.
23. Palettes Pro
This is a great way to create and manage colour palettes to use in your design work, whenever and wherever inspiration strikes. You can sample colours from images, websites or whatever you can find, as well as adding them manually.
24. Todo Cloud
The king of to-do apps, Todo enables you to add and schedule tasks, organise them into various related checklists, map deadlines onto your calendar and keep on top of every aspect of your working life.
The basic version of this app is free, with the option to upgrade for the premium service from $1.99/£1.49.
The winner of Apple's very first App of the Year, Hipstamatic enables you to switch lenses, film and flash settings to create and share highly stylised images. It's also highly expandable, with a broad range of special packs available for in-app purchase.
26. Adobe Photoshop Express
While many of the Touch suite are arguably best suited to iPad, Photoshop Express has some useful tools for photo manipulation on the go that can be just as valuable on iPhone – including filters, effects and basic editing tools. You can also upload files from your device, Creative Cloud, Dropbox, Facebook or Google Photos.
While a picture is worth a thousand words, sometimes you need some words as well to let people know what they're looking at. Over is one of the best iPhone apps for Instagram addicts, Over enables you to add typography to your images quickly and easily.
There's also a feature that lets you find the perfect canvas dimensions for Facebook, Pinterest, Twitter, Instagram, iPhone and even Apple Watch.
Fontli is a social network of type lovers, enabling the community of users to collect and share inspiring examples of typography from everyday life. Using integration with MyFonts database, its iPhone app also features type tagging on pictures.