Color vs Monochrome Cameras
Gaspar van Elmbt
Machine vision has become crucial in many industrial applications such automation, quality control, etc. Machine vision enables efficiency, productivity and accuracy. When selecting an industrial camera, it is very important to select the right type of camera for your specific application. Choosing between color or monochrome cameras will directly affect the efficiency and accuracy of your application. In this article, we will discuss more about why it is important.
Table of contents
Understanding Industrial Cameras
How machine vision light is captured and how the image processing differs mainly from color or monochrome sensors.
Monochrome sensors capture the intensity of light without any color information; each pixel will detect the full range of light intensity, this is why monochrome sensors are 3 times more sensitive and have sharper details. Monochrome sensors do not have a CFA, color filter array, so all light is used for image formation.
Color sensors use a CFA, Bayer filter array to separate light into red, green and blue (RGB). Each of these pixels will only capture one color and the missing colors will be estimated through demosaicing or interpolation. In a color sensor, the final "color" of a pixel is an estimate based on the data from its neighboring pixels. This reinforces why monochrome sensors have higher effective resolution and sharpness. Some color sensors can capture color more accurately by using 3-chip RGB sensors or prism-based systems. These systems don't use a Bayer filter; instead, they split the incoming light with a prism and direct the red, green, and blue components to three separate, dedicated monochrome sensors. This method eliminates the need for demosaicing, offering much higher color accuracy and resolution than a single-sensor camera with a Bayer filter.
Color Cameras
How They Work
- The image sensor produces electrical messages from light; it is made up of a variety of photodiodes that measure the intensity of light.
- The most popular type of CFA is a Bayer filter, which covers the sensor pixels with red, green and blue filters.
- The demosaicing algorithm generates a full color image by demosaicing missing color information.
- Image processors improve image quality by correcting color balance and extracting relevant data for machine vision tasks.
Advantages
- Essential for applications requiring color differentiation, such as object sorting by color, food and fruit sorting solutions, or automotive paint inspections.
- Needed for applications where color accuracy matters.
Disadvantages
- Lower sensitivity compared to monochrome sensors due to Bayer filters blocking part of the incoming light.
- Reduced resolution because of interpolation or demosaicing.
- Additional processing is required for color reconstruction
- Slower image processing due to added color data.
Monochrome Cameras
How They Work
- Incoming light is transformed into an electrical signal by the image sensor. Each pixel’s light intensity is measured by a collection of photodiodes.
- No color filter array is needed, so every pixel receives all the available light.
- It provides a sharp image capture by focusing light onto the sensor.
- Image processors improve sharpness and contrast while extracting pertinent information for analysis.
Advantages
- Higher sensitivity to light and better low-light performance.
- Sharper images and higher contrast, ideal for defect inspections or edge detection.
- Has a wider wavelength sensitivity so can be used for IR and UV applications
Disadvantages
- Cannot capture wide color information, limiting applications where color differentiation is necessary.
Comparison between Monochrome vs Color Cameras
| Feature | Color Camera | Monochrome Camera |
|---|---|---|
|
Sensitivity |
Low due to color filters |
High since there is no filter |
|
Resolution |
Low due to interpolation |
High direct pixel data |
|
Processing Load |
High due to color processing |
Lower |
|
Application Scope |
Color based applications such as sorting or labelling |
Edge detection, texture analysis and low light imaging |
Choosing the Right Camera for Your Application
- When to choose color: Color cameras are ideal when distinguishing between items based on color, such as differentiating between fruits, pills, textiles, etc. Checking for proper labelling, consistency of color in products or detecting discoloration. Mostly for applications that require color identification.
- When to choose monochrome: Monochrome cameras are ideal for low light conditions, the grayscale images offer superior edge detection and defect identification and processing is faster since less computational power is required. Monochrome sensors provide higher effective resolution since every pixel is used for intensity capture.
Concluding Monochrome vs Color Cameras
When color information is not required, monochrome cameras are the better choice, offering clearer details, faster processing, and improved performance in challenging lighting conditions. While color cameras are necessary for tasks that involve color recognition of differentiation, they do come with compromises in sensitivity and image sharpness.
Need help deciding which camera suits your application best? We offer a wide range of monochrome and color industrial cameras for various industries and inspection tasks. Contact us today by filling out the form on our website and we will get back to you as soon as possible with expert advice tailored to your needs.
