Image Processing Quiz

Questions and Answers

Which is a characteristic of LED light?

All the above. (correct)

Have a long life but degrade quickly in a short amount of time.

Always are highly diffuse.

Can be strobed at medium to high duty cycles.

Can be obtained in a variety of physical geometries.

What can the spatial calibration be used for?

Does not improve the measurement resolution.

Can be used to correct for image distortion due to the camera position relative to the object. (correct)

Can be used to correct for lens distortion. (correct)

Can be used to measure the width of an object in real world-units. (correct)

Which is not a feature of Pattern Matching?

Return a score for each match.

Measure the size of objects in the image. (correct)

Return the coordinates of each match.

In managing machine vision, how many sample parts are required for a successful design?

A statistically important number of samples that show all the pass/fail conditions. Signup and view all the answers

Which measure of light power, not weighted to human vision, is appropriate to monochromatic light sources?

Radiometric. Signup and view all the answers

What is the maximum cable length for GigE?

100m. Signup and view all the answers

Which interfaces use GenICam?

A, B & C. Signup and view all the answers

What is a backlight useful for?

All the above. Signup and view all the answers

Which interface has the highest bandwidth possible?

Camera Link HS. Signup and view all the answers

If you increase the working distance, what happens to the FOV?

Decrease. Signup and view all the answers

What of the following changes as the f/# is changed on a lens?

All the above. Signup and view all the answers

Gain cannot be used to increase image quality.

True Signup and view all the answers

If you have a static object with low lighting, what is best to increase?

Exposure. Signup and view all the answers

Which interface has the lowest bandwidth possible?

GigE Vision Signup and view all the answers

Which tool would help you find this fiducial (an image was presented)?

Pattern Matching Signup and view all the answers

Image sensors for visible light are almost always made out of silicon.

True Signup and view all the answers

Is red ring light the best light to use for common applications?

False Signup and view all the answers

What happens when using green LED lighting with red characters and a diffuse background?

Contrast increases Signup and view all the answers

What makes a traditional lens object space telecentric?

Chief ray is parallel to the optical axis in object space. Signup and view all the answers

What happens if you decrease the wavelength in the formula for spot size (d = 2.44 * wavelength * F/#)?

Spot size decreases Signup and view all the answers

Is diffraction the only thing that affects lens performance?

False Signup and view all the answers

If you have a static object with low lighting, what is best to increase?

Gain Signup and view all the answers

What can affect lens performance?

All of the above Signup and view all the answers

Image sensors for visible light are almost always made out of silicon?

True Signup and view all the answers

Is red ring light the best light to use for common applications?

False Signup and view all the answers

What is contrast?

Difference between dark and light pixels Signup and view all the answers

What is required to not get vignetting on the image?

Both 2 and 3 Signup and view all the answers

Which is not a part of integration?

Sales Signup and view all the answers

What is the main difference between CCD and CMOS sensors?

All of the above Signup and view all the answers

What is Quantum Efficiency?

The proportion of light that the sensor converts into charge Signup and view all the answers

What is Full Well Capacity?

Maximum number of electrons that register a signal in a pixel Signup and view all the answers

Is Frame Grabber required for digital cameras?

False Signup and view all the answers

What is dynamic range?

Measure of how well a camera can represent details in bright and dark areas Signup and view all the answers

Which is the first step to define in a vision system?

Lighting and optics Signup and view all the answers

Is contrast the same thing as the camera’s dynamic range?

False Signup and view all the answers

Which image bit-rate provides the largest amount of pixel values?

12 bits Signup and view all the answers

Dark Current Noise error doubles every ____ ° increase in temperature.

8 Signup and view all the answers

Your part is blue, background is white. What color light increases contrast best?

Red Signup and view all the answers

You cannot change the FOV of a Telecentric lens. Need to use a different size lens.

False Signup and view all the answers

As you increase F/# what happens to theoretical contrast?

Decreases Signup and view all the answers

The performance of a lens is determined by both resolution and contrast.

True Signup and view all the answers

Gain cannot be used to increase image quality.

True Signup and view all the answers

The order of visible light from smallest to larger wavelength is:

blue, green, yellow, orange, red Signup and view all the answers

What is the ratio of photons converted to electrons on silicon called?

QE (Quantum Efficiency) Signup and view all the answers

The 'W' pattern diagram describes the relationship between:

dark field and light field lighting Signup and view all the answers

The best lighting technique for inspecting a flat reflective part for scratches is:

Dark field Signup and view all the answers

Blooming and smearing are issues with ____ sensors.

CCD Signup and view all the answers

Correlation matching should be used for parts where:

texture is the main feature Signup and view all the answers

The best form of analysis for a part with varying lighting and reflection is:

Geometric matching Signup and view all the answers

What pattern matching is best for locating the template in the image?

Geometric Signup and view all the answers

Using multiple smart cameras for a broad application would be considered a ____ system.

Distributed Signup and view all the answers

Resolution is characterized by:

lp/mm Signup and view all the answers

Calibration can fix poor lighting.

False Signup and view all the answers

Working distance is the ____.

distance from the object plane to front of lens Signup and view all the answers

Larger pixels ____.

increase SNR Signup and view all the answers

Which interface requires a framegrabber?

Camera Link Signup and view all the answers

8K array resolution is most likely a ____ sensor.

Line scan Signup and view all the answers

An image system consists of:

light, lens, camera (imager, electronics), computer (framegrabber or digital) Signup and view all the answers

A PC based system is the most flexible and has custom processing power.

True Signup and view all the answers

To increase the amount of light interpolated, you should ____.

increase exposure time Signup and view all the answers

Good quality images are optimized for:

contrast between foreground object and background Signup and view all the answers

What is the maximum cable length for GigE?

100m Signup and view all the answers

Which interface has the highest bandwidth possible?

A and B Signup and view all the answers

Which interface has the lowest bandwidth possible?

USB 2 Signup and view all the answers

Which tool would help you find this fiducial?

Pattern Matching Signup and view all the answers

You have some red characters diffuse and a diffuse background. Green LED lighting is used. What happens?

Contrast decreases Signup and view all the answers

The formula for spot size (d) is $d=2.44 \cdot wavelength \cdot F/#$. What happens if you decrease the wavelength?

Spot size decreases Signup and view all the answers

Is diffraction the only thing that affects lens performance?

False Signup and view all the answers

If you have a static object with low lighting, what is best to increase?

Gain Signup and view all the answers

What can affect lens performance?

All of the above Signup and view all the answers

Image sensors for visible light are almost always made out of silicon.

True Signup and view all the answers

Is red ring light the best light to use for common applications?

False Signup and view all the answers

In optics, what is contrast?

Difference between dark and light pixels Signup and view all the answers

An image was shown with a line across a dark circle. Which threshold is the best to extract dark circles from this image?

(0, 71) Signup and view all the answers

What is NOT a characteristic of a ROI?

Make processing speed faster Signup and view all the answers

Showed an image with a histogram ranging from 0 to 255. What image is this?

Grayscale image Signup and view all the answers

What makes a traditional lens object space telecentric?

Chief ray is parallel to the optical axis in object and image space Signup and view all the answers

What is a backlight useful for?

All of the above Signup and view all the answers

Which is not a part of integration?

Sales Signup and view all the answers

First step when developing a vision system.

Analyze functional and system requirements Signup and view all the answers

Which is a necessary skill for a vision professional?

All of the above Signup and view all the answers

Light ray reflected is perpendicular to the ____ ray.

Incident Signup and view all the answers

Light can be:

All of the above Signup and view all the answers

Which are the characteristics of LED light?

Can be strobed at medium and fast duty cycles Signup and view all the answers

Parts of the 3D spatial arrangement are:

Light, object, and camera Signup and view all the answers

For a standard fixed focal length camera as working distance increases, the FOV:

Decreases Signup and view all the answers

Which of the following require GenICam support?

All the above Signup and view all the answers

Which is the first step to define in a vision system?

Vision tools Signup and view all the answers

Pattern matching will do which of the following?

Correct for angle distortions Signup and view all the answers

Light measure of red green blue not weighted to a human eye is called:

Radiometric Signup and view all the answers

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.

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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!