PLEASE NOTE THAT THIS LIBRARY IS NO LONGER ACTIVELY MAINTAINED. USE AT YOUR OWN RISK.
You can also use other libraries, such as UPNG.js or pngjs.
pngparse is a pure-JavaScript library for Node.JS for
converting a PNG file into an array of pixel values. It came out of a need for
reading PNG images in Node.JS for the Dark Sky
API, but all existing libraries either had
compilation issues or did not support enough of the PNG standard to be
practical.
It's reasonably complete, covering most PNG color types, depths, and filters; notable omissions are lack of support for 16-bit images and interlacing.
Comments, bug fixes, feature improvements, etc. are all welcome. If you do write code, please ensure that you write tests for it!
To install:
npm install pngparse
To use:
var pngparse = require("pngparse")
...
pngparse.parse(buffer, function(err, data) {
if(err)
throw err
/* do things! */
})
...
pngparse.parseFile("path/to/file.png", function(err, data) {
if(err)
throw err
/* do things! */
})
The data object returned from the callback bears a striking resemblance to
the HTML5 Canvas ImageData
object. A notable
distinction is that the object returns has a channels property which
indicates how many color channels it uses (while an HTML5 ImageData object is
always 4-channel). The possible color channel combinations are as follows:
1 channel : grayscale
2 channels: grayscale + alpha
3 channels: RGB
4 channels: RGBA
If you use the ImageData.prototype.getPixel method, this is handled for you;
however, if you access the data array manually, then you will have to be
aware of it.
To the extend possible by law, The Dark Sky Company, LLC has waived all copyright and related or neighboring rights to this library.