imagemin-pngquant 
Install
$ npm install imagemin-pngquant
Usage
const imagemin = require('imagemin');
const imageminPngquant = require('imagemin-pngquant');
(async () => {
await imagemin(['images/*.png'], {
destination: 'build/images',
plugins: [
imageminPngquant()
]
});
console.log('Images optimized');
})();API
imageminPngquant(options?)(input)
Returns Promise<Buffer>.
options
Type: object
speed
Type: number
Default: 4
Values: 1 (brute-force) to 11 (fastest)
Speed 10 has 5% lower quality, but is about 8 times faster than the default. Speed 11 disables dithering and lowers compression level.
strip
Type: boolean
Default: false
Remove optional metadata.
quality
Type: Array<min: number, max: number>
Values: Array<0...1, 0...1>
Example: [0.3, 0.5]
Instructs pngquant to use the least amount of colors required to meet or exceed the max quality. If conversion results in quality below the min quality the image won't be saved.
Min and max are numbers in range 0 (worst) to 1 (perfect), similar to JPEG.
dithering
Type: number | boolean
Default: 1 (full)
Values: 0...1
Set the dithering level using a fractional number between 0 (none) and 1 (full).
Pass in false to disable dithering.
posterize
Type: number
Truncate number of least significant bits of color (per channel). Use this when image will be output on low-depth displays (e.g. 16-bit RGB). pngquant will make almost-opaque pixels fully opaque and will reduce amount of semi-transparent colors.
verbose
Type: boolean
Default: false
Print verbose status messages.
input
Type: Buffer | Stream
Buffer or stream to optimize.