Node.js GM randomThreshold() Function

The randomThreshold() function is an inbuilt function in the GraphicsMagick library which is used to apply a random threshold to the image. The function returns the true value of success. 

Syntax:

randomThreshold( channelType, LOWxHIGH )

Parameters: This function accepts two parameters as mentioned above and described below:

• channelType: This parameter is used to specify the value of Channel Type as All, Intensity, Red, Green, Blue, Cyan, Magenta, Yellow, Black, and Opacity.
• LOWxHIGH: This parameter is used to specify the value of the level. The threshold never exceeds the specified maximum (HIGH) and is never less than the specified minimum (LOW).

Return Value: This function returns the GraphicsMagick object. 

Example 1:

javascript

// Include gm library
const gm = require('gm');

// Import the image
gm('1.png')

// Invoke randomThreshold function
// with Channel Type as 'All' and
// lowxhigh as '10x200'
.randomThreshold('All', '10x200')

// Process and Write the image
.write("randomThreshold1.png", function (err) {
    if (!err) console.log('done');
});

Output:

Example 2: 

javascript

// Include gm library
const 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 random Threshold function
// with Channel Type as 'Green' and
// lowxhigh as 100x600
.randomThreshold('Green', '100x600')

// Process and write the image
.write("randomThreshold2.png", function (err) {
    if (!err) console.log('done');
});

Output:

Reference:

• http://www.graphicsmagick.org/GraphicsMagick.html#details-randomThreshold
• https://www.npmjs.com/package/gm