Blue Line

News
Digital imaging better, faster, cheaper


March 3, 2015
By Tom Rataj

It’s been some time since I looked at the world of digital imaging and much has happened in the ensuing years.

The smartphone has savaged much of the traditional dedicated camera market, particular the low end point & shoot category. Many people who would not ordinarily carry a camera now always have one available. Many camera owners just leave them at home because their smartphone takes pictures of adequate quality for most purposes.

Most higher-end smartphones now feature built-in cameras with sensor resolution upwards of 10 or even 20 megapixels. They often include image-stabilization and other technology, producing pretty-decent images even under poor conditions.

Adding all these cameras to everyday life has resulted in many changes. Just look at all the smartphone photos and videos which show up daily in the news media. This has many implications for law-enforcement. We are constantly scandalized by the media, which broadcasts raw, out of context smartphone video of police use-of-force incidents.

On the positive side, law enforcement benefits largely from the presence of personally owned smartphone cameras in the hands of officers in the field. There are some potential disclosure and legal issues with officers using their personal smartphones for official business, but I haven’t read of many problems and the benefits probably far outweigh the risks.

{Image sensors}

Probably the single most important factor to overall image quality (even more important than the megapixel count) is sensor size. A bigger sensor gathers more light, in the same way that a bigger window lets more light into a building. The more light, the better the image.

Smartphones typically have very small sensors. Those in point & shoot cameras are generally three to four times larger.

Moving up-market, the standard APS-C sized sensor, which is the most common size, is substantially larger than those in point & shoot cameras. It is used in most consumer and professional digital single lens reflex (DSLR) models, as well as the market leading Sony Compact System Camera (CSC).

While Sony’s Alpha series cameras (formerly branded NEX) leads the CSC market, Panasonic and Olympus follow with their slightly smaller, jointly-developed, Micro 4/3 sensor equipped lines. Samsung’s NX-sensor based cameras have a sensor fractionally larger than standard APS-C.

Full-frame (35mm film camera equivalent) sensors are at the top of the market and were until recently limited to a few DSLR models from Canon, Nikon and Sony.

Sony upset the full-frame market last year with its A7 line of full-frame sensor equipped CSCs – substantially smaller and lighter than standard DSLR cameras (including Sony’s own full-sized A99).

A variety of other image sensors are limited to professional and specialized markets.

{Image sensor overview}

Mick has chart

{Lenses}

The lens is the second most important factor for image quality. Larger diameter lenses allow in more light, resulting in better overall performance, especially in low light.

Smartphones generally only have a small fixed focal-length lens so when the user zooms into an image, the camera software just magnifies the centre of the image in a process known as digital zoom. Regular cameras typically have optical zoom, where the focal-length is changed by moving the lens elements forward and backward in relation to the sensor.

If the image sensor and lens are of good enough quality and size, and the sensor has a high megapixel count, zooming-in digitally will produce a decent image, but only to a point. Digital zoom is no match for optical zoom.

There are a wide variety of lenses for every imaginable purpose available for cameras with interchangeable lenses. They can be broken down roughly to fixed focal-length lenses such as a 50 or 85mm lens and zoom-lenses with a range of focal-lengths.

A top-quality name-brand lens can easily cost more than the camera body. Lens mounts are different for each brand, although adapters allow the use of virtually any lens with any camera.

{Mega-Pixels}

The megapixel count in cameras is determined by multiplying the number of pixels (or photosites – the little electronic sensors that turn light into the digital signal) along the vertical and horizontal axis of the sensor.

Pixel counts don’t tell the entire image story. The actual size of the pixels also makes a big difference. Again, think of the big window vs. little window analogy.

Two cameras with the same effective megapixel rating can have very different pixel sizes, depending on the size of the image sensor. As shown in the chart above, a smartphone or point & shoot camera has a much smaller sensor than an APS-C equipped camera. Even with the same megapixel count, the smaller sensor will have much smaller pixels than the larger sensor, again negatively affecting image quality.

The biggest general advantage of more megapixels is the ability to crop an area out of a frame and enlarge it while still maintaining quality.

Canon recently upped the megapixel ante by announcing its new EOS 5DS ($4,099.99) and EOS 5DS R ($4,299.99) models (available in June), a pair of full-frame 50.6 MP DSLR cameras. Sony and Nikon are both rumoured to be working on 50 MP equipped full-frame cameras so Canon’s lead won’t last long.

{Imaging in policing}

With the affordability and versatility of digital cameras, I find it interesting that there are not more out in the field.

Issuing every front-line police officer with a quality point & shoot camera as standard equipment would be a huge benefit for virtually every aspect of policing.

So many cases would benefit from digital imaging, even if it’s only a quick half-dozen photos. Instead of calling in scarce scenes-of-crime or forensic officers (or officers using their personal smartphones) to photograph a scene or incident, a trained officer with a digital camera could quickly document the situation.

Just imagine the benefit of more photographs at traffic collisions, thefts, assaults or other incidents. Expensive court time could be reduced, while case quality would increase greatly.

It could be as simple as telling officers to “photograph anything that you think you should,” but would probably require a more detailed policy. There would be some peripheral costs for cases, batteries and secure archiving of images.

Body-worn video-cameras will not supplant the need for more digital cameras in the field, primarily because they have a more specific purpose and generally don’t have the still-image quality and versatility of a real camera.