# How to adjust the contrast of an image using contrast() function in Node Jimp?

Node.jsServer Side ProgrammingProgramming

NodeJS – Contrast() is an inbuilt function that is used to adjust the contrast of images. It will increase or decrease the contrast based upon the input value that ranges from -1 to +1.

## Syntax

contrast(n, cb)

## Definition of contrast() paramters

• – It will take n as an input for adjusting the contrast of the image, Possible values of n is between -1 and +1.

• cb – This is an optional parameter that can be invoked after the compilation is complete.

## Using Node JIMP – CONTRAST()

Before proceeding to use contrast() functions, please check that the following statements are already executed for setting up the environment.

• npm init -y // Initialising the Node environment

• npm install jimp --save // Installing the jimp dependency

• Create a contrast.js file and copy-paste the following code snippet in it.

• Use node contrast.js to run the code.

Note: Note that the method name should match with the JS file name. Only then it will be able to call the desired method.

### Example

const Jimp = require('jimp') ;

async function contrast() { // Function name is same as of file name
('/home/jimp/tutorials_point_img.jpg');
image.contrast(.4)
.write('/home/jimp/contrast.jpg');
}

contrast(); // Calling the function here using async
console.log("Image is processed successfully");

## Using Node JIMP – Contrast() with 'cb' parameters

### Example

const Jimp = require('jimp') ;

async function contrast() {
('/home/jimp/tutorials_point_img.jpg');
image.contrast(-0.5, function(err){
if (err) throw err;
})
.write('/home/jimp/contrast.jpg');
}

contrast();
console.log("Image is processed successfully");

### Output

Published on 27-Apr-2021 13:13:10