We’ll release our new app, Hydra for iPhone and iPad, in the next few weeks. And although it shares the same name as the Mac app, it’s a different beast. Hydra for iOS is about getting the most out of the sensor of your mobile device camera. It’s packed with innovative capture and image processing technology that will help you in difficult lighting conditions.
Camera sensors of mobile devices improved a lot in the past few years. Image quality is pretty amazing, and iPhones have become the most popular camera in the world (see https://www.flickr.com/cameras). Moreover, an iPhone is a device you carry with you all the time.
Yet, because of their physical size, the sensors of mobile devices have limitations. If you compare a full-frame sensor (DSLR) and a smartphone sensor, there is a ratio of 50 between their relative areas (see picture below). The quantity of light is proportional to the photo receptor area in the sensor.
That’s the reason why Apple keeps them at 8 megapixels (MP), because increasing pixel count would decrease individual pixel area, decrease image quality & increase noise (less light).
Is there really nothing we can do to improve image quality? We’ve come up with an idea: getting more light by processing many images and merging them together to produce a better photo.
This is not an easy task, because the camera is moving when shooting (hand motion), and processing many images is resource-hungry. Hopefully, nowadays GPUs (the graphics chip) are extremely powerful, and all this has become possible. Moreover, Apple did open up new camera APIs in iOS 8, which make it a lot easier to control camera parameters while shooting.
And we could even propose a few different modes for specific capture conditions. Hydra has 5 different capture modes:
• High Dynamic Range (HDR) made of up to 20 images.
• Video-HDR, single-frame tonemapping.
• Low-Light mode, with 10x light amplification & noise reduction.
• Zoom, making use of 2x and 4x super resolution from hand motion.
• High-Resolution mode, with up to 32-megapixel photos.
Unlike more standard HDR methods, Hydra will process up to 20 pictures to produce its final image (the actual number depends on the scene). The tonemapper is pretty standard with 3 options (Black and white, regular, strong), and special care was taken to make it robust to hand-held shooting. Video-HDR shifts input exposure to capture more highlight (single frame), and applies the tonemapper to retrieve more details as well as the dark parts. It also makes use of new capture options of iPhone 6 and 6+.
Hydra’s Lo-light mode aggregates together multiple images, amplifying light coming from the scene, and decreasing sensor noise. This brings much higher image quality in difficult lighting conditions, which are typically hard to shoot with a mobile phone.
Zoom & Hi-res modes use a special technique known as super resolution. It uses the motion between successive frames to reconstruct a higher resolution image. In Zoom mode, Hydra can achieve 2x or 4x that is more accurate than standard digital zooming techniques. In Hi-res mode, Hydra will produce up to 32-megapixel images from the standard 8-megapixel camera sensor.
These modes also have limitations though. Their force and at the same time their weakness is that they rely on multiple photos to produce a single image. This means moving subjects, or scenes with parallax subjects (simultaneous near & far subjects), can create moiré patterns. But keeping that in mind and with practice, you should be able to create stunning photos that you can’t otherwise. Hydra really is about having additional shooting options that you can use when needed.
We’d like to have Hydra shipping as soon as possible, possibly at the end of this month. Stay tuned for more!