Questions and Answers
Which is a characteristic of LED light?
What can the spatial calibration be used for?
Which is not a feature of Pattern Matching?
In managing machine vision, how many sample parts are required for a successful design?
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Which measure of light power, not weighted to human vision, is appropriate to monochromatic light sources?
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What is the maximum cable length for GigE?
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Which interfaces use GenICam?
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What is a backlight useful for?
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Which interface has the highest bandwidth possible?
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If you increase the working distance, what happens to the FOV?
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What of the following changes as the f/# is changed on a lens?
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Gain cannot be used to increase image quality.
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If you have a static object with low lighting, what is best to increase?
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Which interface has the lowest bandwidth possible?
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Which tool would help you find this fiducial (an image was presented)?
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Image sensors for visible light are almost always made out of silicon.
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Is red ring light the best light to use for common applications?
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What happens when using green LED lighting with red characters and a diffuse background?
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What makes a traditional lens object space telecentric?
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What happens if you decrease the wavelength in the formula for spot size (d = 2.44 * wavelength * F/#)?
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Is diffraction the only thing that affects lens performance?
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If you have a static object with low lighting, what is best to increase?
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What can affect lens performance?
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Image sensors for visible light are almost always made out of silicon?
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Is red ring light the best light to use for common applications?
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What is contrast?
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What is required to not get vignetting on the image?
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Which is not a part of integration?
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What is the main difference between CCD and CMOS sensors?
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What is Quantum Efficiency?
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What is Full Well Capacity?
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Is Frame Grabber required for digital cameras?
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What is dynamic range?
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Which is the first step to define in a vision system?
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Is contrast the same thing as the camera’s dynamic range?
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Which image bit-rate provides the largest amount of pixel values?
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Dark Current Noise error doubles every ____ ° increase in temperature.
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Your part is blue, background is white. What color light increases contrast best?
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You cannot change the FOV of a Telecentric lens. Need to use a different size lens.
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As you increase F/# what happens to theoretical contrast?
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The performance of a lens is determined by both resolution and contrast.
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Gain cannot be used to increase image quality.
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The order of visible light from smallest to larger wavelength is:
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What is the ratio of photons converted to electrons on silicon called?
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The 'W' pattern diagram describes the relationship between:
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The best lighting technique for inspecting a flat reflective part for scratches is:
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Blooming and smearing are issues with ____ sensors.
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Correlation matching should be used for parts where:
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The best form of analysis for a part with varying lighting and reflection is:
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What pattern matching is best for locating the template in the image?
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Using multiple smart cameras for a broad application would be considered a ____ system.
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Resolution is characterized by:
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Calibration can fix poor lighting.
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Working distance is the ____.
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Larger pixels ____.
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Which interface requires a framegrabber?
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8K array resolution is most likely a ____ sensor.
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An image system consists of:
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A PC based system is the most flexible and has custom processing power.
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To increase the amount of light interpolated, you should ____.
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Good quality images are optimized for:
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What is the maximum cable length for GigE?
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Which interface has the highest bandwidth possible?
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Which interface has the lowest bandwidth possible?
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Which tool would help you find this fiducial?
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You have some red characters diffuse and a diffuse background. Green LED lighting is used. What happens?
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The formula for spot size (d) is $d=2.44 \cdot wavelength \cdot F/#$. What happens if you decrease the wavelength?
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Is diffraction the only thing that affects lens performance?
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If you have a static object with low lighting, what is best to increase?
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What can affect lens performance?
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Image sensors for visible light are almost always made out of silicon.
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Is red ring light the best light to use for common applications?
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In optics, what is contrast?
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An image was shown with a line across a dark circle. Which threshold is the best to extract dark circles from this image?
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What is NOT a characteristic of a ROI?
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Showed an image with a histogram ranging from 0 to 255. What image is this?
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What makes a traditional lens object space telecentric?
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What is a backlight useful for?
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Which is not a part of integration?
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First step when developing a vision system.
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Which is a necessary skill for a vision professional?
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Light ray reflected is perpendicular to the ____ ray.
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Light can be:
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Which are the characteristics of LED light?
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Parts of the 3D spatial arrangement are:
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For a standard fixed focal length camera as working distance increases, the FOV:
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Which of the following require GenICam support?
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Which is the first step to define in a vision system?
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Pattern matching will do which of the following?
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Light measure of red green blue not weighted to a human eye is called:
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Study Notes
Image Bit-rate and Pixel Values
- 12 bits provide the largest amount of pixel values, allowing for greater color depth compared to 8, 10, or 4 bits.
Dark Current Noise
- Dark current noise doubles every 8°C increase in temperature, impacting image quality.
Contrast Enhancement
- Using red light increases contrast best for blue parts on white backgrounds.
Telecentric Lenses
- Cannot change the Field of View (FOV) of a telecentric lens without using a different size lens.
- Telecentric lenses maintain fixed z-axis magnification.
Theoretical Contrast
- Increasing F/# leads to a decrease in theoretical contrast.
Lens Performance
- Lens performance is determined by both resolution and contrast.
Gain and Image Quality
- Gain cannot be used to enhance image quality.
Visible Light Spectrum
- The order of visible light from smallest to largest wavelength is blue, green, yellow, orange, red.
Quantum Efficiency
- The ratio of photons converted to electrons on silicon is referred to as Quantum Efficiency (QE).
Lighting Techniques
- Dark field lighting is best for inspecting flat reflective surfaces for scratches.
- Lighting type impacts the qualities of the captured image; red ring lighting is not universally the best.
Sensor Issues
- Blooming and smearing are common issues associated with CCD sensors.
Image Analysis Techniques
- Correlation matching is effective when texture is the primary feature.
- For parts with varying lighting, geometric matching is the best analysis method.
Pattern Matching for Template Location
- Geometric pattern matching outperforms correlation matching when locating templates in images with stacked parts.
Smart Cameras
- Using multiple smart cameras is classified as a distributed system.
Resolution and Characterization
- Resolution is characterized by line pairs per millimeter (lp/mm).
Calibration
- Calibration cannot rectify poor lighting conditions.
Working Distance
- Defined as the distance from the object plane to the front of the lens.
Pixel Size and Signal-to-Noise Ratio (SNR)
- Larger pixels increase SNR, leading to better image quality.
Image Interfaces
- Camera Link is the specific interface that requires a frame grabber.
- The maximum cable length for GigE connections is 100 meters.
Spot Size Formula
- The formula for spot size indicates that a decrease in wavelength results in a smaller spot size.
Definition of Contrast
- Contrast in optics is defined as the difference between dark and light pixels.
Regions of Interest (ROI)
- ROIs can improve processing speed and can be shaped like lines or rectangles.
Backlighting
- Backlighting is beneficial for edge detection, gauging, and seeing translucent materials.
Basic Principles of Light
- Light can be absorbed, reflected, transmitted, or emitted.
Lens Performance Factors
- Factors affecting lens performance include wavelength, F/#, and working distance.
Initial System Design Steps
- The first step in developing a vision system is analyzing functional and system requirements.
Characteristics of LED Light
- LEDs can be strobed at various duty cycles and have a long lifespan but may degrade quickly.
Chromatic Aberrations
- These aberrations can occur both on-axis and off-axis in lenses.
Maximum Length for Connectivity
- USB 2 has the lowest bandwidth among the major interfaces used.
Importance of Lighting
- Good quality images are primarily shaped by contrast between the foreground object and the background, influencing operator appeal.
Image Thresholds
- Proper thresholds for image analysis can help extract specific features; examples include dark circles in histograms identified by specific ranges.
Common Lens Characteristics
- For lenses, changes in working distance directly influence the FOV, which may increase or decrease based on design and configuration choices.
Integration in Vision Systems
- Integration involves design, vision tools programming, and communication, with sales being less critical.
Focal Plan Requirements
- For a PMAG of 1, the FOV must be smaller than the sensor size to avoid distortion.
Communication Standards
- GenICam support is required for GigE, Camera Link, and CoaXpress interfaces.### Image Analysis and Types
- Histogram values between 0 and 255 represent grayscale images (8-bit).
- A backlight serves multiple purposes: edge detection, gauging, facilitating vision-guided robotics, and revealing semi-transparent materials.
- Contrast indicates the intensity difference between blacks and whites in an image.
- ROI (Region of Interest) is defined as a specific area for image processing but is not a coordinate system (fixture).
Optical Systems and Sensors
- Traditional lenses are object space telecentric when the chief ray is parallel to the optical axis in object space.
- Light interaction with surfaces can occur through reflection, transmission, absorption, and emission.
- Characteristics of LED light include high diffusion, variability in geometries, and long life with degradation over time.
- To avoid vignetting in images, the lens size should ideally match or exceed the sensor size, maintaining a minimum diameter ratio.
Image Processing and Camera Technology
- Digital cameras generally do not require a frame grabber due to direct electronic integration.
- Temporal noise arises from fluctuations over time (e.g., temperature changes), while spatial noise is fixed and influenced by sensor design.
- CCD sensors produce higher image quality through better pixel uniformity and reduced noise, while CMOS sensors offer faster image acquisition and lower costs.
- Gain adjusts the signal strength captured by the sensor, impacting the exposure, noise, and image quality.
System Development and Integration
- Initial steps in developing a vision system involve analyzing functional and system requirements before defining vision tools.
- Integration factors do not include sales; they focus on design and implementation of vision tools and communication systems.
- Successful system design may require a statistically significant number of sample parts to visualize pass/fail scenarios.
Lighting and Gain
- Gain increases visibility by amplifying both signal and noise, but excessive gain doesn't necessarily improve image quality.
- For static low-light scenarios, increasing exposure time is preferable to enhance visibility.
- Illumination characteristics, such as geometry, structure, color, and filtering (GSCF), greatly influence system performance.
Measurement and Specifications
- Full Well Capacity refers to the maximum electrons a pixel can register; larger pixels translate to better sensitivity and dynamic range.
- Dynamic range (DR) measures a camera's ability to represent details across bright and dark areas, capturing more information.
- Various imaging interfaces such as GigE Vision, USB, and Camera Link differ in bandwidth, with Camera Link typically offering the highest capabilities.
Color and Contrast
- Camera design affects quantum efficiency (QE), which reflects the proportion of light converted into measurable charge.
- The Bayer pattern in color sensors results in certain disadvantages, including reduced effective spatial resolution and increased manufacturing costs.
- Rolling shutter effects in CMOS sensors can be mitigated using strobe lighting to alleviate motion blurring.
Conclusion
- Understanding the interaction of light, sensor technology, and system design principles is essential in machine vision applications.
- Conflicting requirements, such as resolution versus implementation cost, must always be carefully balanced for optimal performance.
Studying That Suits You
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Description
Test your knowledge on image processing concepts with this quiz covering topics like bit-rate, dark current noise, and color contrast. Answer multiple-choice questions to assess your understanding of the field. Perfect for students in related courses!