Image filtering (gaussian_filter) in SciPy - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the gaussian_filter function in image processing?

The gaussian_filter smooths an image by reducing noise and detail using a Gaussian kernel, which blurs the image gently.

beginner

What does the sigma parameter control in gaussian_filter?

The sigma parameter controls the amount of blurring. A larger sigma means more blur and smoothing.

intermediate

How does gaussian_filter handle edges of an image by default?

By default, gaussian_filter uses 'reflect' mode, which mirrors the image edges to avoid artifacts during filtering.

beginner

Write a simple Python code snippet using scipy.ndimage.gaussian_filter to blur a 2D image array named image with sigma=2.

from scipy.ndimage import gaussian_filter
blurred_image = gaussian_filter(image, sigma=2)

intermediate

Why might you choose gaussian_filter over a simple average filter for image smoothing?

Because gaussian_filter weights nearby pixels more than distant ones, it preserves edges better and produces more natural blurring than a simple average filter.

What effect does increasing the sigma value have in gaussian_filter?

A Inverts the image colors

B Sharpens the image

C Increases the blur effect

D Removes the image edges

Increasing sigma increases the blur by spreading the Gaussian kernel wider.

Which library provides the gaussian_filter function?

A scipy.ndimage

B matplotlib

C numpy

D pandas

gaussian_filter is part of the scipy.ndimage module.

What is the default mode for handling image edges in gaussian_filter?

A constant

B reflect

C nearest

D wrap

The default mode is 'reflect', which mirrors the edges to reduce artifacts.

Which of these is a benefit of using a Gaussian filter over a simple mean filter?

A It completely removes noise

B It sharpens the image

C It increases image contrast

D It preserves edges better

Gaussian filters weight pixels by distance, preserving edges better than mean filters.

If you want less blur with gaussian_filter, what should you do?

A Decrease sigma

B Increase sigma

C Increase image size

D Use a different image format

Decreasing sigma reduces the blur effect.

Explain how the gaussian_filter works for image smoothing and why it is preferred over simple averaging.

Think about how weighting pixels differently affects the image.

Describe how you would apply gaussian_filter to a noisy image and what parameters you might adjust.

Focus on the function call and parameter roles.