Mathis/sharp
1
0
Fork 0
mirror of https://github.com/lovell/sharp.git synced 2025-12-19 07:15:08 +01:00
Code Issues Packages Projects Releases Wiki Activity

Use libvips' new lanczos3 kernel as default for image reduce

Browse Source 
Deprecate interpolateWith method, now provided as an option
This commit is contained in:
Lovell Fuller
2016-05-17 22:16:47 +01:00
parent 051d022fc2
commit cdb2894bd9
32 changed files with 292 additions and 658 deletions
Download Patch File Download Diff File Expand all files Collapse all files

69
docs/api.md
View File

@@ -118,7 +118,7 @@ Do not process input images where the number of pixels (width * height) exceeds
### Resizing
#### resize([width], [height])
#### resize([width], [height], [options])
Scale output to `width` x `height`. By default, the resized image is cropped to the exact size specified.
@@ -126,6 +126,42 @@ Scale output to `width` x `height`. By default, the resized image is cropped to
`height` is the integral Number of pixels high the resultant image should be, between 1 and 16383. Use `null` or `undefined` to auto-scale the height to match the width.
`options` is an optional Object. If present, it can contain one or more of:
* `options.kernel`, the kernel to use for image reduction, defaulting to `lanczos3`.
* `options.interpolator`, the interpolator to use for image enlargement, defaulting to `bicubic`.
Possible kernels are:
* `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
* `lanczos2`: Use a [Lanczos kernel](https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel) with `a=2`.
* `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
Possible interpolators are:
* `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
* `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), faster than bicubic but with less smooth results.
* `vertexSplitQuadraticBasisSpline`: Use the smoother [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48) to prevent "staircasing" when enlarging.
* `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation) (the default).
* `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)" but typically reduces performance by a factor of 2.
* `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance but typically reduces performance by a factor of 3.
```javascript
sharp(inputBuffer)
.resize(200, 300, {
kernel: sharp.kernel.lanczos2,
interpolator: sharp.interpolator.nohalo
})
.background('white')
.embed()
.toFile('output.tiff')
.then(function() {
// output.tiff is a 200 pixels wide and 300 pixels high image
// containing a lanczos2/nohalo scaled version, embedded on a white canvas,
// of the image data in inputBuffer
});
```
#### crop([option])
Crop the resized image to the exact size specified, the default behaviour.
@@ -232,37 +268,6 @@ if its width or height exceeds the geometry specification*".
Ignoring the aspect ratio of the input, stretch the image to the exact `width` and/or `height` provided via `resize`.
#### interpolateWith(interpolator)
Use the given interpolator for image resizing, where `interpolator` is an attribute of the `sharp.interpolator` Object e.g. `sharp.interpolator.bicubic`.
The default interpolator is `bicubic`, providing a general-purpose interpolator that is both fast and of good quality.
Possible interpolators, in order of performance, are:
* `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation), suitable for image enlargement only.
* `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), faster than bicubic but with less smooth results.
* `vertexSplitQuadraticBasisSpline`: Use the smoother [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48) to prevent "staircasing" when enlarging.
* `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation) (the default).
* `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)" but typically reduces performance by a factor of 2.
* `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance but typically reduces performance by a factor of 3.
[Compare the output of these interpolators](https://github.com/lovell/sharp/tree/master/test/interpolators)
```javascript
sharp(inputBuffer)
.resize(200, 300)
.interpolateWith(sharp.interpolator.nohalo)
.background('white')
.embed()
.toFile('output.tiff')
.then(function() {
// output.tiff is a 200 pixels wide and 300 pixels high image
// containing a nohalo scaled version, embedded on a white canvas,
// of the image data in inputBuffer
});
```
### Operations
#### extract({ left: left, top: top, width: width, height: height })

5
docs/changelog.md
View File

@@ -6,6 +6,11 @@ Requires libvips v8.3.1
#### v0.15.0 - TBD
* Use libvips' new Lanczos 3 kernel as default for image reduction.
Deprecate interpolateWith method, now provided as a resize option.
[#310](https://github.com/lovell/sharp/issues/310)
[@jcupitt](https://github.com/jcupitt)
* Take advantage of libvips v8.3 features.
Add support for libvips' new GIF and SVG loaders.
Pre-built binaries now include giflib and librsvg, exclude *magick.