Computer Knowledge

Digital Image Processing

2,103 Questions

Digital image processing involves manipulating digital images through various algorithms to enhance their visual quality or extract information. Key concepts include noise reduction, high dynamic range imaging, color correction, and sharpening techniques. These concepts are essential for computer science exams and technical certifications.

Color management systemsNoise reduction techniquesHDR image combiningImage sharpening techniquesAlpha matting process

Digital Image Processing Questions

Multiple choice

Which of the following is NOT a recommended technique for reducing noise and grain in a sharpened image?

  1. Applying noise reduction before sharpening.

  2. Using a sharpening algorithm that is designed to reduce noise.

  3. Sharpening the image in multiple passes with a low sharpening amount.

  4. Sharpening the image at a low resolution.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sharpening the image at a low resolution is not a recommended technique for reducing noise and grain.

Multiple choice

Which of the following is NOT a recommended technique for sharpening an image for web use?

  1. Using a sharpening radius of 1-2 pixels.

  2. Applying sharpening selectively to specific areas of the image.

  3. Using a sharpening algorithm that is designed for web images.

  4. Sharpening the image at a low resolution.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sharpening the image at a low resolution is not a recommended technique for sharpening an image for web use.

Multiple choice

What is the primary cause of halos and edge artifacts when sharpening an image using a high-pass filter?

  1. Using a sharpening radius that is too large.

  2. Applying too much sharpening overall.

  3. Sharpening an image that is already sharp.

  4. Using a high-pass filter with a low cutoff frequency.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using a high-pass filter with a low cutoff frequency can cause halos and edge artifacts because it enhances high-frequency details too much, leading to an unnatural and exaggerated appearance.

Multiple choice

Which of the following is NOT a recommended technique for sharpening an image for social media use?

  1. Using a sharpening radius of 1-2 pixels.

  2. Applying sharpening selectively to specific areas of the image.

  3. Using a sharpening algorithm that is designed for social media images.

  4. Sharpening the image at a high resolution.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sharpening the image at a high resolution is not a recommended technique for sharpening an image for social media use.

Multiple choice

What is the term used to describe the process of reconstructing the wavefront distortions from the measurements obtained by wavefront sensors?

  1. Wavefront reconstruction

  2. Wavefront sensing

  3. Deformable mirror control

  4. Adaptive optics correction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Wavefront reconstruction is the process of estimating the wavefront distortions from the measurements obtained by wavefront sensors.

Multiple choice

Which type of adaptive optics system is used to correct for large-scale wavefront distortions?

  1. Multi-conjugate adaptive optics

  2. Single-conjugate adaptive optics

  3. Ground-layer adaptive optics

  4. Tomographic adaptive optics
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Multi-conjugate adaptive optics systems are used to correct for large-scale wavefront distortions by using multiple deformable mirrors.

Multiple choice

What is the term used to describe unintended streaks or patches of light in a photograph due to light leaks?

  1. Vignetting

  2. Light Leaks

  3. Ghosting

  4. Bokeh
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Light Leaks occur when light enters the camera body through unintended openings, causing streaks or patches of light in the image.

Multiple choice

What is the term used to describe the gradual darkening of the edges of a photograph?

  1. Vignetting

  2. Light Leaks

  3. Film Grain

  4. Chromatic Aberration
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Vignetting is the gradual darkening of the edges of a photograph, often caused by the lens or camera body design.

Multiple choice

What type of filter can help reduce glare and reflections when shooting in bright, sunny conditions?

  1. Neutral density filter

  2. Polarizing filter

  3. UV filter

  4. Graduated neutral density filter
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A polarizing filter helps reduce glare and reflections by blocking certain wavelengths of light, resulting in more saturated colors and improved contrast.

Multiple choice

Which of the following is NOT a common method for sharpening images in macro photography?

  1. Unsharp Mask

  2. High Pass Filter

  3. Median Filter

  4. Gaussian Blur
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Median Filter is a noise reduction technique, not a sharpening technique. Unsharp Mask, High Pass Filter, and Gaussian Blur are all commonly used for sharpening images.

Multiple choice

What is the primary difference between Unsharp Mask and High Pass Filter sharpening methods?

  1. Unsharp Mask sharpens edges more than High Pass Filter

  2. High Pass Filter sharpens edges more than Unsharp Mask

  3. Unsharp Mask is more effective at reducing noise

  4. High Pass Filter is more effective at reducing noise
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

High Pass Filter is generally considered to be more aggressive in sharpening edges compared to Unsharp Mask, but it can also introduce more noise.

Multiple choice

What is the best way to preview the effects of sharpening before applying it to an image?

  1. Use the histogram

  2. Zoom in to 100%

  3. Apply the sharpening and then undo it

  4. Use the sharpening slider
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Zooming in to 100% allows you to see the effects of sharpening on the fine details of the image.

Multiple choice

What is the recommended sharpening workflow for macro photography?

  1. Sharpen the image before noise reduction

  2. Sharpen the image after noise reduction

  3. Sharpen the image multiple times

  4. Sharpen the image only if it is blurry
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is generally recommended to apply noise reduction before sharpening to avoid amplifying noise during the sharpening process.

Multiple choice

Which of the following assumptions is commonly made in closed-form matting algorithms?

  1. The background is locally smooth.

  2. The foreground object has sharp edges.

  3. The image contains only a single foreground object.

  4. The illumination is uniform across the image.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Closed-form matting algorithms often assume that the background is locally smooth, meaning that the color and intensity values of neighboring pixels in the background are similar.

Multiple choice

Which of the following closed-form matting algorithms is known for its simplicity and efficiency?

  1. Bayesian Matting

  2. Poisson Matting

  3. Closed-Form Matting

  4. Random Walk Matting
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Closed-Form Matting, also known as Trimap Matting, is a simple and efficient closed-form matting algorithm that estimates the alpha matte based on a user-provided trimap, which consists of regions labeled as foreground, background, and unknown.