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Add summary of JPEG and PNG optimisation features

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Lovell Fuller 2014-03-10 22:32:14 +00:00
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@ -11,9 +11,11 @@ The typical use case for this high speed Node.js module is to convert large JPEG
The performance of JPEG resizing is typically 15x-25x faster than ImageMagick and GraphicsMagick, based mainly on the number of CPU cores available. The performance of JPEG resizing is typically 15x-25x faster than ImageMagick and GraphicsMagick, based mainly on the number of CPU cores available.
When generating JPEG output all metadata is removed and Huffman tables optimised without having to use separate command line tools like [jpegoptim](https://github.com/tjko/jpegoptim) and [jpegtran](http://jpegclub.org/jpegtran/).
This module supports reading and writing images to and from both the filesystem and Buffer objects (TIFF is limited to filesystem only). Everything remains non-blocking thanks to _libuv_. This module supports reading and writing images to and from both the filesystem and Buffer objects (TIFF is limited to filesystem only). Everything remains non-blocking thanks to _libuv_.
Anyone who has used the Node.js bindings for [GraphicsMagick](https://github.com/aheckmann/gm) will find the API similarly expressive. Anyone who has used the Node.js bindings for [GraphicsMagick](https://github.com/aheckmann/gm) will find the API similarly fluent.
This module is powered by the blazingly fast [libvips](https://github.com/jcupitt/libvips) image processing library, originally created in 1989 at Birkbeck College and currently maintained by John Cupitt. This module is powered by the blazingly fast [libvips](https://github.com/jcupitt/libvips) image processing library, originally created in 1989 at Birkbeck College and currently maintained by John Cupitt.
@ -91,7 +93,7 @@ sharp('input.jpg').resize(200, 300).embedBlack().webp(function(err, buffer) {
throw err; throw err;
} }
// buffer contains WebP image data of a 200 pixels wide and 300 pixels high image // buffer contains WebP image data of a 200 pixels wide and 300 pixels high image
// containing a scaled version, embedded on a black canvas, of input.png // containing a scaled version, embedded on a black canvas, of input.jpg
}); });
``` ```
@ -129,7 +131,7 @@ Perform a mild sharpen of the resultant image. This typically reduces performanc
### progressive() ### progressive()
Use progressive (interlace) scan for the output. This typically reduces performance by 30%. Use progressive (interlace) scan for JPEG and PNG output. This typically reduces compression performance by 30% but results in an image that can be rendered sooner when decompressed.
### sequentialRead() ### sequentialRead()