You're reading from Mastering OpenCV 4 with Python

Product typeBook

Published inMar 2019

Reading LevelExpert

PublisherPackt

ISBN-139781789344912

Edition1st Edition

Languages

Python

Tools

OpenCV

Concepts

Computer Vision

Author (1)

Alberto Fernández Villán

Grayscale histograms

OpenCV provides the cv2.calcHist() function in order to calculate the histogram of one or more arrays. Therefore, this function can be applied to single-channel images (for example, grayscale images) and to multi-channel images (for example, BGR images).

In this section, we are going to see how to calculate histograms for grayscale images. The signature for this function is as follows:

cv2.calcHist(images, channels, mask, histSize, ranges[, hist[, accumulate]])

To this, the following applies:

images: It represents the source image of type uint8 or float32 provided as a list (example, [gray_img]).
channels: It represents the index of the channel for which we calculate the histogram provided as a list (for example, [0] for grayscale images, or [0],[1],[2] for multi-channel images to calculate the histogram for the first, second, or third channel, respectively...

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Mastering OpenCV 4 with Python

Published in: Mar 2019Publisher: PacktISBN-13: 9781789344912

Author (1)

Alberto Fernández Villán

Alberto Fernndez Villn is a software engineer with more than 12 years of experience in developing innovative solutions. In the last couple of years, he has been working in various projects related to monitoring systems for industrial plants, applying both Internet of Things (IoT) and big data technologies. He has a Ph.D. in computer vision (2017), a deep learning certification (2018), and several publications in connection with computer vision and machine learning in journals such as Machine Vision and Applications, IEEE Transactions on Industrial Informatics, Sensors, IEEE Transactions on Industry Applications, IEEE Latin America Transactions, and more. As of 2013, he is a registered and active user (albertofernandez) on the Q&A OpenCV forum.
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