6 most important attributes to consider when selecting an industrial camera

Selecting an industrial camera is a strenuous process for people that are new to the field as well as professionals. This is because there is a long list of attributes to consider for any given application. Industrial cameras are useful for a wide range of tasks. However, these tasks generally put the cameras in two categories or types; The area scan and the line scan cameras.

 

Line and Area Scan Camera

The design of the line scan camera allows it to scan objects in one dimension to produce two-dimensional images. The images constructed using these cameras are usually in very high resolution as a result of the cameras using a single row of pixels for their tasks. The application areas suitable for line scan cameras are those where cylindrical objects, objects in motion,  long or continuous materials such as paper and plastic need to be inspected for defects. While it can be argued that most of these tasks can be accomplished using the area scan cameras, the line scan camera has an edge when the object moves at high speed and high resolution is required. On the other hand, area scan cameras are designed to capture images in two-dimensions using an array of pixels. These cameras are more flexible, they offer an easier setup and alignment process than the line scan camera and can be used for a range of tasks where the object is stationary (even if it is for a moment) and in a specified field of view. With the area scan camera, an image can be segmented into various regions-of-interest to investigate specific areas rather than processing the entire image. An example where the area scan camera would be more beneficial is when inspecting an object such as a bottle for defects like scratches. Such defects are usually only visible when viewed from certain angles which can be effectively produced with the area scan camera.  

 

Industrial Camera Attributes

Understand all the attributes that are taken into consideration when selecting an industrial camera would require its own article to fully bring it to life and taking a look at 6 attributes (the Sensor type, Sensor size/format, Resolution, Pixel size/Pixel Pitch, Frame Rate/Line Rate, and the Shutter type) we are able to recognize the role each sensor attribute plays and visualize what makes them so important.

• Sensor Type: The sensor type refers to the technology the sensor uses to capture light and convert it into the images for processing. There are many sensors used to capture light. These sensors are relatively similar to one another with their main difference being how the light is captured and converted to an image. Some of the more popular sensors are the CCD, CMOS, and EMCCD sensors. 

• Sensor size/format: The sensor size or format describes the light-sensitive areas of the camera and both the area scan and the line scan cameras have different sensor sizes. The dimensions are usually not standardized and results from the resolution and pixel sizes of the sensors.  

• Resolution: Images captured using a camera are made up of various pixels. The camera resolution refers to the number of pixels in a given sensor and having more pixels equals a higher resolution in the sensor.  

• Pixel size: Pixels are used to capture light and when put together, form an image. The pixel size describes the size of the pixels in the camera sensor which in turn affects how much noise there is in the image as smaller pixel sizes have been found to have more noise than the larger ones when viewed at pixel level.

• Frame /Line Rate:  Cameras are able to capture objects multiple times in a second. In an area scan camera, we refer to the frame rate for this feature and it is denoted as Hz or fps (Hertz or Frames per second). In a line scan camera, we lookout for the line rate and it is denoted as kHz (Kilohertz). If the object(s) to be inspected would be moving at high speed, it would be beneficial to select sensors that have higher frame/line rates.

• Shutter Type: During the exposure time of the camera, the pixels are activated in a certain pattern to absorb light and the shutter type controls how the camera sensor is exposed to light. There are two types of shutters and cameras usually come with one or the other. These types are the rolling shutter and the global shutter.
  • Global Shutter: For a global shutter, all the pixels are activated at the same time in order to capture light for a given amount of time (that is the shutter speed) and this can affect how much motion blur would appear in a shot if an object is moving fast. 
  • Rolling Shutter: For a rolling shutter, the pixels are activated one row at a time for the length of the shutter speed. Cameras with this shutter type have shown to have skewed images if the object being captured is moving fast

The differences between the camera types and deciding which solution would fit best for a given task can be a bit overwhelming to grasp at first. However, once the requirements for a specific problem is understood, it becomes easier to recognize the importance of the various attributes. While the attributes are being examined, there are a few that should be carefully considered as they give an overview of the quality of the camera. These attributes are the Sensor type, Sensor size/format, Resolution, Pixel size/Pixel Pitch, Frame Rate/Line Rate, and the Shutter type.