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102 lines
2.6 KiB
Markdown
102 lines
2.6 KiB
Markdown
<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
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### Table of Contents
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- [background][1]
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- [greyscale][2]
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- [grayscale][3]
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- [toColourspace][4]
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- [toColorspace][5]
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## background
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Set the background for the `embed`, `flatten` and `extend` operations.
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The default background is `{r: 0, g: 0, b: 0, alpha: 1}`, black without transparency.
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Delegates to the _color_ module, which can throw an Error
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but is liberal in what it accepts, clipping values to sensible min/max.
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The alpha value is a float between `0` (transparent) and `1` (opaque).
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**Parameters**
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- `rgba` **([String][6] \| [Object][7])** parsed by the [color][8] module to extract values for red, green, blue and alpha.
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- Throws **[Error][9]** Invalid parameter
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Returns **Sharp**
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## greyscale
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Convert to 8-bit greyscale; 256 shades of grey.
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This is a linear operation. If the input image is in a non-linear colour space such as sRGB, use `gamma()` with `greyscale()` for the best results.
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By default the output image will be web-friendly sRGB and contain three (identical) color channels.
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This may be overridden by other sharp operations such as `toColourspace('b-w')`,
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which will produce an output image containing one color channel.
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An alpha channel may be present, and will be unchanged by the operation.
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**Parameters**
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- `greyscale` **[Boolean][10]** (optional, default `true`)
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Returns **Sharp**
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## grayscale
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Alternative spelling of `greyscale`.
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**Parameters**
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- `grayscale` **[Boolean][10]** (optional, default `true`)
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Returns **Sharp**
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## toColourspace
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Set the output colourspace.
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By default output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
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**Parameters**
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- `colourspace` **[String][6]?** output colourspace e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...][11]
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- Throws **[Error][9]** Invalid parameters
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Returns **Sharp**
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## toColorspace
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Alternative spelling of `toColourspace`.
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**Parameters**
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- `colorspace` **[String][6]?** output colorspace.
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- Throws **[Error][9]** Invalid parameters
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Returns **Sharp**
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[1]: #background
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[2]: #greyscale
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[3]: #grayscale
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[4]: #tocolourspace
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[5]: #tocolorspace
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[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
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[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
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[8]: https://www.npmjs.org/package/color
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[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
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[10]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
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[11]: https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568
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