Node.js GM channel() Function
The channel() function is an inbuilt function in the GraphicsMagick library which is used to extract a particular channel from the image.
Syntax:
channel( channelType )
Parameters: This function accepts a single parameter channelType which holds the type of channel name. The types of channels are Red, Green, Blue, Opacity, Matte, Cyan, Magenta, Yellow, Black, or Gray.
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 borderColor() function // and set border color to green .borderColor( 'Green' ) // Invoke resize function .border(10, 30) // Invoke Channel function // with 'All' parameter .channel( 'All' ) // Process and Write the image .write( "channel-all1.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, "w3wiki!" ) // Invoke borderColor() function // and set border color to green .borderColor( "Green" ) // Invoke border function .border(62, 32) // Invoke Channel function // with 'All' parameter .channel( 'Green' ) // Process and write the image .write( "channel-green.png" , function (err) { if (!err) console.log( 'done' ); }); |
Output:
Reference:
- http://www.graphicsmagick.org/GraphicsMagick.html#details-channel
- https://www.npmjs.com/package/gm
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