Terminologies related to Smartphone Camera
In the leading article, Pixels, pixel size, megapixels and sensors in a smartphone camera were explained. Below are other related terminologies.
This is used to describe how big or small an image sensor is. The size determines how much light can enter the camera, and this in turn affects the image quality.
In the first part of this article, the sensor was described as the device that captures the light that enters the camera. The size of a smartphone camera sensor is expressed in inches (“) or fractions of an inch. The closer the size is to an inch the bigger the sensor.
To avoid confusion, this is the same as pixels and it makes up the camera’s megapixels count. It is sometimes referred to as microns and it is measured in micrometers (µm). Photosites work with the mission of gathering light, so, the larger the photosites the more light they can gather. This quality is essentially used in taking pictures in low-light conditions.
The camera shutter works like the eyelids. The shutter opens and closes to let light enter the camera to capture the image. The shutter speed is the time taken for the shutter to remain open before it closes to allow light in. This in turn affects the brightness of the image. For the image to be bright, it requires the shutter speed to be slow.
International Standards Organization (ISO)
ISO is the popular term used to describe this on the spec list. It means the rating of the image sensitivity for camera sensors. The darker the light, the higher the ISO is the rule governing this rating number.
Although, increasing the ISO isn’t advisable as the image produced looks grainy.
This is the adjustable opening between the camera lens and the sensor. It controls the amount of light that the sensor captures. It is measured in f-stops or f-numbers. F-number is the ratio of the focal length of the camera to the physical diameter of the aperture (e.g f/16, f/2). The smaller the diameter of the aperture( that is, the denominator of the f-number) the less light passes through while the bigger the diameter of the aperture, the more light passes through. In the human eye, an aperture is likened to the pupil.
Aperture also controls the overall sharpness of the image and helps achieve a shallow depth of field.
Depth of field
This is the area of the image in focus. An image with everything in focus has a deeper depth of field compared to an image with just the background in focus. The one with just the background is said to have a shallow depth of field. The aperture controls this quality. A camera with a lower f-number produces images with a shallow depth of field while a camera with a higher f-number produces images with a deeper depth of field.
Stability is an important criteria to take the perfect memorable picture or video. You do not want your photos to come out blurry. Tripods provide stability to the phone but they cannot be carried around. This is why smartphones these days are embedded with technology that tries to reduce the effect of instability on the image to be produced. The technology is in form of Optical image stabilization (OIS), Electronic image stabilization (EIS), and Hybrid image stabilization (HIS)
Optical image stabilization (OIS)
This technology works using a gyroscope sensor (this is used to achieve a balanced image) and electromagnets. The gyroscope spots the smartphone’s instability and adjusts while the electromagnets move the lenses and sensor to accommodate the change. In low light conditions, this type of image stabilization is useful because while adjusting the lenses, it is gathering light. It is also useful in recording videos.
Electronic image stabilization (EIS)
This technology is dependent on the smartphone’s accelerometer (to detect vibration). This enables it to move the image frame when a vibration is spotted. This type reduces the resolution of the image or video because the image frame is being adjusted based on the image content and not the frame of the image sensor.
Hybrid image stabilization (HIS)
Just as the name suggests, it is the combination of both Optical image stabilization and Electronic image stabilization. The way technology works make it easy to extract the best from both forms.