Adventures in Machine Learning

Mastering Image Processing with Mahotas Library in Python

Mahotas Library is a Python library that is used for image processing and computer vision tasks. It provides an extensive range of features for image processing, including filtering, segmentation, feature extraction, and image analysis.

In this article, we will explore how Mahotas Library can be used to import and display images, calculate the mean of an image, and perform various other image processing tasks.

Installing Mahotas Library

Before we can use Mahotas Library, we need to install it. One of the easiest ways to install the library is to use the pip command in the terminal.

Here is the command for installing Mahotas Library using pip:

“`

pip install mahotas

“`

Once the library is installed, we can start working on image processing tasks using Mahotas.

Importing and Displaying Images using Mahotas Library

Importing images is one of the fundamental tasks when working with image processing. Mahotas Library provides the imread() function that can be used to read an image.

Here is an example of how to read an image using Mahotas Library:

“`

import mahotas as mh

from pylab import imshow, show

img = mh.imread(‘image.jpg’)

“`

The `imshow()` function can be used to display the imported image. Here is an example of how to display the image:

“`

imshow(img)

show()

“`

In the above example, we use `imshow()` to display the imported image and `show()` to display the plot.

Mean Calculation using Mahotas Library

Calculating mean of an image is a common image processing task. Mahotas Library provides the `mean()` function that can be used to calculate the mean of an image.

Here is an example of how to calculate the mean of an image using Mahotas Library:

“`

import mahotas as mh

from pylab import imshow, show

img = mh.imread(‘image.jpg’)

img_mean = img.mean()

print(‘Mean of the image:’, img_mean)

“`

In the above example, we use `mean()` to calculate the mean of the imported image and print the result.

Image Filtering using Mahotas Library

Mahotas Library provides various techniques for image filtering, such as Gaussian filtering, median filtering, and Sobel filtering. Here is an example of how to perform Gaussian filtering using Mahotas Library:

“`

import mahotas as mh

from pylab import imshow, show

img = mh.imread(‘image.jpg’)

img_filtered = mh.gaussian_filter(img, sigma = 5)

imshow(img_filtered)

show()

“`

In the above example, we use the `gaussian_filter()` function to apply Gaussian filtering to the imported image and display the filtered image.

Image Segmentation using Mahotas Library

Image segmentation is the process of dividing an image into multiple regions. Mahotas Library provides various techniques for image segmentation, such as thresholding, watershed, and region growing.

Here is an example of how to perform thresholding segmentation using Mahotas Library:

“`

import mahotas as mh

from pylab import imshow, show

img = mh.imread(‘image.jpg’)

thresh = img.mean()

img_thresholded = img > thresh

imshow(img_thresholded)

show()

“`

In the above example, we use thresholding to segment the imported image and display the segmented image.

Feature Extraction using Mahotas Library

Mahotas Library provides various techniques for feature extraction, such as Harris corner detection, SIFT, and SURF. Here is an example of how to perform Harris corner detection using Mahotas Library:

“`

import mahotas as mh

from pylab import imshow, show

img = mh.imread(‘image.jpg’)

corners = mh.corner_harris(img)

imshow(corners)

show()

“`

In the above example, we use `corner_harris()` to detect corners in the imported image and display the detected corners.

Conclusion

Mahotas Library provides a wide range of features for image processing and computer vision tasks. In this article, we explored how to install Mahotas Library, import and display images, calculate the mean of an image, perform various image processing tasks such as image filtering and segmentation, and perform feature extraction.

By using Mahotas Library, it is possible to perform various complex image processing tasks in a straightforward and efficient manner.

3) Image Cropping using Mahotas Library

Image cropping is a technique used to extract a portion of an image. This technique is commonly used in various image processing and computer vision applications.

Mahotas Library provides a simple and efficient way to crop images in Python.

Cropping images using Mahotas Library

The `crop()` function in Mahotas Library can be used to crop an image. The `crop()` function takes the coordinates of the top-left and bottom-right corners of the region to be cropped as inputs.

Here is an example of how to crop an image using Mahotas Library:

“`

import mahotas as mh

from pylab import imread, imshow, show

img = imread(‘image.jpg’)

cropped_img = img[100:300, 200:400]

imshow(cropped_img)

show()

“`

In the above example, we define the `cropped_img` variable by extracting a region from the original `img` variable by specifying the top-left and bottom-right corners of the region. The cropped image is then displayed using the `imshow()` and `show()` functions.

4) Roundness Calculation using Mahotas Library

Roundness is a measure of how close an object is to being a perfect circle. In image processing, roundness is an essential parameter used to distinguish shapes and identify different objects.

Mahotas Library provides functions to calculate the roundness of an object in an image.

Calculating roundness of an image using Mahotas Library

There are various ways to calculate the roundness of an object in an image. One of the most commonly used approaches is to calculate the circularity or circular variance of the object.

The circularity is defined as the ratio of the area of the object to the area of a circle with the same perimeter. Mahotas Library provides the `perimeter()` and `area()` functions to calculate the perimeter and area of an object in an image.

Using these functions, we can calculate the circularity of the object. Here is an example of how to calculate the roundness of an object using Mahotas Library:

“`

import mahotas as mh

from pylab import imread, imshow, show

img = mh.imread(‘image.jpg’)

thresh = img.mean()

img_thresholded = img > thresh

labeled, nr_objects = mh.label(img_thresholded)

regions = mh.regionprops(labeled)

for prop in regions:

roundness = 4 * prop.area * np.pi / (prop.perimeter ** 2)

print(‘Roundness:’, roundness)

“`

In the above example, we perform thresholding segmentation on the imported image, label the objects, and calculate the roundness of each object using the `area()` and `perimeter()` functions. We then print the calculated roundness for each object.

Conclusion

In this article, we explored two additional image processing techniques using Mahotas Library: image cropping and roundness calculation. We learned how to use the `crop()` function to extract a region from an image and how to calculate the roundness of an object in an image using the `area()` and `perimeter()` functions.

By using these techniques, it is possible to extract important information from images and perform various image processing tasks.

5) Local Maxima Detection using Mahotas Library

Detecting the local maxima of an image is a common image processing task that is often used in computer vision applications. Mahotas Library provides a simple and efficient way to detect local maxima in an image.

Detecting local maxima of an image using Mahotas Library

The `mahotas` library provides the `locmax()` function to detect local maxima of an image. The `locmax()` function takes an image as input and returns a binary image where the local maxima are represented by white pixels.

Here is an example of how to detect local maxima of an image using Mahotas Library:

“`

import mahotas as mh

from pylab import imread, imshow, show

img = imread(‘image.jpg’)

local_maxima_img = mh.locmax(img)

imshow(local_maxima_img)

show()

“`

In the above example, we define the `local_maxima_img` variable using the `locmax()` function, which detects and marks the local maxima of the image. The resulting binary image is then visualized using the `imshow()` function.

6) Grayscale Image Generation using Overlay Image

Generating grayscale images is a common image processing task used in computer vision and image analysis applications. Overlay images are a type of image where a binary mask or image is used to produce a grayscale image.

Mahotas Library offers a straightforward way of generating grayscale images using overlay images.

Generating grayscale images using Mahotas Library

The `mahotas` library provides the `overlay()` function to generate grayscale images using an overlay image. The `overlay()` function takes two inputs, an image and a binary mask or overlay image.

The output is a grayscale image where the values in the overlay are used to determine the color of the pixels in the input image. Here is an example of how to generate a grayscale image using an overlay image using Mahotas Library:

“`

import mahotas as mh

from pylab import imread, imshow, show

img = imread(‘image.jpg’)

thresh = img.mean()

img_thresholded = img > thresh

gray_img = mh.overlay(img, img_thresholded)

imshow(gray_img)

show()

“`

In the above example, we perform thresholding segmentation on the imported image and generate a binary mask using the thresholded image. We then generate a grayscale image using the overlay image generated from the binary mask.

The resulting grayscale image is displayed using the `imshow()` and `show()` functions.

Conclusion

In this article, we explored two additional image processing techniques using Mahotas Library: local maxima detection and grayscale image generation using overlay images. We learned how to use the `locmax()` function to detect local maxima in an image and the `overlay()` function to generate grayscale images using overlay images.

By using these techniques, it is possible to extract important information from images and perform various image processing tasks. In this article, we explored the various image processing techniques that can be performed using the Mahotas Library in Python.

We learned how to import and display images, calculate the mean of an image, perform image filtering and segmentation, perform feature extraction, crop an image, calculate roundness, detect local maxima, and generate grayscale images using overlay images. These techniques are essential for various computer vision and image processing applications.

Mahotas Library provides an efficient and straightforward way to perform these tasks in Python. By mastering these techniques, researchers and developers can perform high-quality image processing tasks and extract vital information from images.