## Core function: change the contrast and brightness of the image OpenCV v4.8.0

Previous tutorial: Adding (blending) two images using OpenCV Next tutorial: Discrete Fourier Transform Original author Ana Huamán Compatibility OpenCV >= 3.0 Goals In this tutorial you will learn how to Access pixel values Initialize matrix with zeros Learn what cv::saturate_cast does and its usefulness Get some cool information about pixel transforms Improve image brightness with […]

## Core function: Discrete Fourier transform OpenCV v4.8.0

Previous tutorial: Changing the contrast and brightness of an image Next tutorial: Input and output files using XML and YAML files Original author Bernát Gábor Compatibility OpenCV >= 3.0 Goals We will seek answers to the following questions: What is the Fourier transform and why is it used? How to do Fourier transform in OpenCV? […]

## Scope functions in Kotlin: why use them? When to use?

Scoped functions are very useful in Kotlin and help us manage our code and write clear and readable code. What is a scope function? The Kotlin standard library contains several functions whose sole purpose is to execute a block of code within the context of an object. When we call such a function on an […]

## Kingbase ES function return-return statement

Article Summary: This article is at https://www.cnblogs.com/kingbase/p/15703611.html Based on this article, we summarize the return statements that functions in Kingbase ES can support. On the basis that they are generally compatible with Oracle, they are also the same as PG syntax. At the same time, sqlserevr table-valued functions and code failure cases are listed. One, […]

## Core function: mask operation of matrix OpenCV v4.8.0

Previous tutorial : How to scan an image, lookup table and measure time using OpenCV Next tutorial: Image manipulation Original author Bernát Gábor Compatibility OpenCV >= 3.0 Masking operations on matrices are very simple. The principle is that we recalculate the value of each pixel in the image based on the mask matrix (also called […]

## [Functional Programming] Lambda, Stream, Optional, method reference, parallel stream

New features of JDK1.8 The main new features in JDK1.8 include: lambda expression Stream Optional functional interface method reference Due to the adaptive parallel flow technology, these advanced features can achieve higher operating efficiency in massive data scenarios without JUC concurrent programming optimization. The number of lines of code is greatly simplified, making it more […]

## [MySQL] Basic query (3) Aggregation function + group by

Article directory 1. Aggregation function 2. group by clause Conclusion Create the following table //Create table structure mysql> create table exam_result( -> id int unsigned primary key auto_increment, -> name varchar(20) not null comment ‘Classmate’s name’, -> chinese float default 0.0 comment ‘Chinese score’, -> math float default 0.0 comment ‘math score’, -> english float […]

## Process control wait and waitpid functions

When a process terminates normally or abnormally, the kernel sends the SIGCHLD signal to its parent process. Because child process termination is an asynchronous event (this can occur at any time while the parent process is running), this signal is also an asynchronous notification sent by the kernel to the parent process. The parent process […]

## kingbase ES about NULL and related functions

Article Summary: This article mainly discusses the NULL value and its related processing functions, and also introduces the ora_input_emptystr_isnull parameter. One, about NULL value 1, null value in sql The null value represents unknown data, or an uncertain value, which is different from the empty string and 0. Null values are treated differently than other […]