Raspberry Pi has launched a Global Shutter Camera, available for $50.
The new camera is built around Sony’s 1.6-megapixel IMX296 sensor, enabling it to capture rapid motion without introducing rolling shutter artefacts.
It is well suited to machine vision applications and sports photography, according to Raspberry Pi.
Raspberry Pi has released a number of cameras since its first Camera Module 1 was introduced in 2014, each of which has been based on a rolling shutter sensor.
Rolling shutter sensors have a two-dimensional array of light-sensitive pixels that generate an analogue value proportional to the amount of light falling on the pixel during the exposure time. A row of analogue-to-digital converters (ADCs) converts the analogue values into digital values that are then fed back to the Raspberry Pi.
The row of ADCs is connected to each row of the pixel array in turn, so each row is sampled at a slightly different time. While this isn’t a problem when imaging static scenes, for moving scenes – particularly those in which something is moving fast – rolling shutter artefacts are observed. Linear motion results in compression, stretching, or shearing of the moving object, while rotary motion can create even stranger-looking shapes. Such artefacts are difficult to correct and can interfere with the operation of machine vision algorithms.
To eliminate image artefacts, a global shutter sensor must instead be used. This design pairs each pixel with an analogue storage element, meaning that when the shutter fires, each pixel immediately copies its analogue value into its storage element, from where it can be read and converted at leisure. The storage element adds complexity and area to each pixel. Global shutter sensors therefore tend to have a lower resolution than rolling shutter sensors of the same size.
The new Raspberry Pi Global Shutter Camera combines the C/CS-mount metalwork of the firm’s High Quality Camera with Sony’s IMX296 sensor. It can be used with any Raspberry Pi computer that has a CSI camera connector.
Below is a video of the new device in action, illustrating the benefits of a global shutter in the presence of rapid rotary motion.
