Nodejs | GM contrast() Function

The contrast() function is an inbuilt function in the GraphicsMagick library which is used to enhance or reduce the contrast of the image. The function returns the true value on success.

Syntax:

contast(multiplier)

Parameters: This function accepts a single parameter multiplier which is the factor by which the contrast of image should increase or decrease.

Return Value: This function returns the GraphicsMagick object.

Example 1:



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// Include gm library
var gm = require('gm');
  
// Import the image
gm('1.png')
  
// Invoke contrast function
.contrast(10)
  
// Process and Write the image
.write("contrast1.png", function (err) {
  if (!err) console.log('done');
});

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Output:

Example 2:

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// Include gm library
var gm = require('gm');
  
// Import the image
gm(600, 300, 'white')
  
// Set the color for the stroke
.stroke("green", 3)
  
// Set the font 
.font("Helvetica.ttf", 60)
  
// Call to drawText Function
.drawText(100, 280, "GeeksforGeeks!")
  
// Invoke borderColor() function
// and set border color to green
.borderColor("Green")
  
// Invoke border function
.border(62, 32)
  
// Invoke contrast function
.contrast(-14)
  
// Process and Write the image
.write("contrast2.png", function (err) {
  if (!err) console.log('done');
});

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Output:

Reference:




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