crop-image-stream

Crop an image stream

Crops a raw image stream, returns a cropped raw image stream, compatible with pixel-stream. Everything is streams, so you can crop giant images without a memory overhead, only one line of the input image is held in memory at a time.

Table of Contents

• Installation
• Usage
• API
• Contribute
• License

Install

npm i --save crop-image-stream

Usage

See examples.

var fs = require('fs')
var path = require('path')
var JPEGDecoder = require('jpg-stream/decoder')
var JPEGEncoder = require('jpg-stream/encoder')

var Crop = require('crop-image-stream')

var inputFilename = path.join(__dirname, 'dramatic_chipmunk.jpg')
var outputFilename = path.join(__dirname, 'dramatic_chipmunk_crop.jpg')

var cropOpts = {
  x: 575,
  y: 20,
  width: 275,
  height: 200
}

fs.createReadStream(inputFilename)
  .pipe(new JPEGDecoder())
  .pipe(Crop(cropOpts))
  .pipe(new JPEGEncoder())
  .pipe(fs.createWriteStream(outputFilename))

API

var Crop = require('crop-image-stream')

Crop(opts)

Where:

• opts.x - X coordinate of left side of crop area, measured from the left of the original image. Default 0
• opts.y - Y coordinate of top of crop area, measured from the top of the original image. Default 0
• opts.width - Width of crop area. Default input image width. If opts.x + opts.width > inputImageWidth, the crop area width will be inputImageWidth - opts.x
• opts.height - Height of crop area. Default input image height. If opts.y + opts.height > inputImageHeight, the crop area height will be inputImageHeight - opts.y

You must pipe a stream of raw image data that emits a format event with format = {height: inputImageHeight, width: inputImageWidth, colorSpace: inputImageColorSpace. Returns a stream of raw image data which will also emit a format event. Compatible with pixel-stream but does not support frames (animated images).

Contribute

PRs accepted.

Small note: If editing the Readme, please conform to the standard-readme specification.

License

MIT © Digital Democracy