Adobe Photoshop Express | Price: Free | Size: 6.6MB | iTunes link
There can be no article about photo editing on the iPhone without the inevitable inclusion of Photoshop Express. Adobe's mobile software may not be the most advanced one in terms of features, but it definitely gets the job done when it comes to essential tasks such as cropping, exposure, saturation, contrast, etc. What adds value to the deal is its price tag of free.
PhotoForge | Price: $2.99 | Size: 4.7MB | iTunes link
PhotoForge is another heavyweight that might be pretty well-known to some of you, but its incredibly wide array of functions just earned its mention once again. Being one of the most profound iPhone apps for the purpose, PhotoForge lets you do so many kinds of stuff to your images that we feel we'll run out of space if start listing. Hit the iTunes link for all the magic.
CameraBag | Price: $1.99 | Size: 0.3MB | iTunes link
What CameraBag does can be categorized as more of a stylization than editing, but still, we find its capabilities of adding an artistic touch to seemingly regular photos potentially valuable. CameraBag sports about 14 different “cameras”, or rather filters, which you can quickly switch between in order to see which one will best suit your photo.
FX Photo Studio | Price: $1.99 | Size: 19.7MB | iTunes link
While we're on the topic of photo filters and effects, FX Photo Studio seems like a real powerhouse as it comes with a total of 181 effects, divided into 19 categories, plus some basic goodies such as a crop tool, brightness adjustment, etc. With so much options to choose from, we guess FX Photo Studio makes for a great choice for those who enjoy experimenting by adding various filters to their images.
PhotoPad | Price: Free | Size: 7MB | iTunes link
For its free price, PhotoPad seems like a pretty well feature-packed photo editing application for the iPhone and iPad. It allows you to apply various color effects, crop images, paint, adjust colors, contrast and saturation, as well as use different tools like red eye detection and so on. Not as complete as PhotoForge, but still a fine free offering.