The relationship between line scan camera line rate and exposure time
In image processing systems, a line scan camera is a common device that captures images by scanning lines on the surface of an object. In this process, exposure time is a crucial parameter that directly affects the clarity and detail of the image. This article examines the relationship between line rate and exposure time of line scan cameras.
First, we need to understand what line rate is. For a line scan camera, the line rate refers to the vertical distance traveled by the camera during a scan. For example, if the line rate of a camera is 200 lines/mm, it must cover 200*2=400 vertical pixels when scanning an object with a height of 2 mm.
The exposure time refers to the time that the light-sensitive element of the camera (e.g. CCD or CMOS) is exposed to light. The length of the exposure time affects the brightness and details of the image. The longer the exposure time, the brighter the image, but overexposure can also occur; the shorter the exposure time, the darker the image, but more details can be retained.
So, what is the relationship between the Line Rate and the exposure time of the line scan camera? This mainly depends on two factors: one is the reflectivity of the object surface, and the other is the resolution of the camera.
For objects with high reflectivity, such as metal, glass, etc., because they can strongly reflect light, it is possible to obtain a bright enough image even if the exposure time is short. However, if the exposure time is too short, the image may be overexposed and lose details. Therefore, for this type of object, it is usually necessary to choose a longer exposure time.
On the other hand, the resolution of the camera will also affect the choice of exposure time. A camera with a higher resolution has more pixels, and the less information each pixel can record. Therefore, in order to obtain sufficient information, the exposure time needs to be increased. Conversely, a camera with a lower resolution requires a shorter exposure time.
In simpler terms, the higher the Line Rate, the shorter the exposure time needs to be. This is because the camera needs to receive more light during an exposure cycle to produce satisfactory photo effects. On the contrary, if the Line Rate is lower, the exposure time needs to be longer.Camera exposure can be long and short. If you want to learn about linear array camera exposure knowledge, you can read: Multi Line Technology: Long and Short Exposure HDR .
In short, the relationship between Line Rate and exposure time of line scan cameras is not fixed, but needs to be adjusted according to specific shooting conditions. In actual operation, we need to choose an appropriate exposure time based on the reflectivity of the object surface and the resolution of the camera to ensure the clarity and details of the image.