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Expose libvips interpolators #69

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Lovell Fuller
2014-08-22 16:50:24 +01:00
parent 6498fc3a9e
commit 017bf1e905
4 changed files with 112 additions and 46 deletions
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@@ -110,21 +110,33 @@ image.metadata(function(err, metadata) {
```
```javascript
var pipeline = sharp().rotate().resize(null, 200).progressive().toBuffer(function(err, outputBuffer, info) {
if (err) {
throw err;
}
// outputBuffer contains 200px high progressive JPEG image data, auto-rotated using EXIF Orientation tag
// info.width and info.height contain the final pixel dimensions of the resized image
});
var pipeline = sharp()
.rotate()
.resize(null, 200)
.progressive()
.toBuffer(function(err, outputBuffer, info) {
if (err) {
throw err;
}
// outputBuffer contains 200px high progressive JPEG image data,
// auto-rotated using EXIF Orientation tag
// info.width and info.height contain the dimensions of the resized image
});
readableStream.pipe(pipeline);
```
```javascript
sharp('input.png').rotate(180).resize(300).sharpen().quality(90).webp().toBuffer().then(function(outputBuffer, info) {
// outputBuffer contains 300px wide, upside down, sharpened, 90% quality WebP image data
// info.width and info.height contain the final pixel dimensions of the resized image
});
sharp('input.png')
.rotate(180)
.resize(300)
.sharpen()
.quality(90)
.webp()
.toBuffer()
.then(function(outputBuffer) {
// outputBuffer contains 300px wide, upside down, sharpened,
// 90% quality WebP image data
});
```
```javascript
@@ -137,10 +149,16 @@ http.createServer(function(request, response) {
```
```javascript
sharp(inputBuffer).resize(200, 300).bicubicInterpolation().embedWhite().toFile('output.tiff').then(function() {
// output.tiff is a 200 pixels wide and 300 pixels high image containing a bicubic scaled
// version, embedded on a white canvas, of the image data in buffer
});
sharp(inputBuffer)
.resize(200, 300)
.interpolateWith(sharp.interpolator.nohalo)
.embedWhite()
.toFile('output.tiff')
.then(function() {
// output.tiff is a 200 pixels wide and 300 pixels high image
// containing a bicubic scaled version, embedded on a white canvas,
// of the image data in inputBuffer
});
```
```javascript
@@ -247,17 +265,17 @@ This is equivalent to GraphicsMagick's `>` geometry option: "change the dimensio
Perform a mild sharpen of the resultant image. This typically reduces performance by 30%.
#### bilinearInterpolation()
#### interpolateWith(interpolator)
Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation) for image resizing, the default (and fastest) interpolation if none is specified.
Use the given interpolator for image resizing, where `interpolator` is an attribute of the `sharp.interpolator` Object e.g. `sharp.interpolator.bicubic`.
#### bicubicInterpolation()
Possible interpolators, in order of performance, are:
Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation) for image resizing. This typically reduces performance by 5%.
#### nohaloInterpolation()
Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/) for image resizing. This typically reduces performance by a factor of 2.
* `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), the default (and fastest) interpolation.
* `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation), which typically reduces performance by 5%.
* `vertexSplitQuadraticBasisSpline`: Use [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48), which prevents "staircasing" when enlarging and typically reduces performance by 5%.
* `locallyBoundedBicubic`: Use [LBB interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/lbb.cpp#L100), which prevents some "[acutance](http://en.wikipedia.org/wiki/Acutance)" and typically reduces performance by a factor of 2.
* `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance and typically reduces performance by a factor of 3.
### Output options