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Docs: mention removal of metadata in output methods
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lovell committed Sep 25, 2019
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177 changes: 93 additions & 84 deletions docs/api-output.md
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Expand Up @@ -8,12 +8,15 @@ If an explicit output format is not selected, it will be inferred from the exten
with JPEG, PNG, WebP, TIFF, DZI, and libvips' V format supported.
Note that raw pixel data is only supported for buffer output.

By default all metadata will be removed, which includes EXIF-based orientation.
See [withMetadata][1] for control over this.

A `Promise` is returned when `callback` is not provided.

### Parameters

- `fileOut` **[String][1]** the path to write the image data to.
- `callback` **[Function][2]?** called on completion with two arguments `(err, info)`.
- `fileOut` **[String][2]** the path to write the image data to.
- `callback` **[Function][3]?** called on completion with two arguments `(err, info)`.
`info` contains the output image `format`, `size` (bytes), `width`, `height`,
`channels` and `premultiplied` (indicating if premultiplication was used).
When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
Expand All @@ -32,15 +35,19 @@ sharp(input)
.catch(err => { ... });
```

- Throws **[Error][3]** Invalid parameters
- Throws **[Error][4]** Invalid parameters

Returns **[Promise][4]<[Object][5]>** when no callback is provided
Returns **[Promise][5]<[Object][6]>** when no callback is provided

## toBuffer

Write output to a Buffer.
JPEG, PNG, WebP, TIFF and RAW output are supported.
By default, the format will match the input image, except GIF and SVG input which become PNG output.

If no explicit format is set, the output format will match the input image, except GIF and SVG input which become PNG output.

By default all metadata will be removed, which includes EXIF-based orientation.
See [withMetadata][1] for control over this.

`callback`, if present, gets three arguments `(err, data, info)` where:

Expand All @@ -54,9 +61,9 @@ A `Promise` is returned when `callback` is not provided.

### Parameters

- `options` **[Object][5]?**
- `options.resolveWithObject` **[Boolean][6]?** Resolve the Promise with an Object containing `data` and `info` properties instead of resolving only with `data`.
- `callback` **[Function][2]?**
- `options` **[Object][6]?**
- `options.resolveWithObject` **[Boolean][7]?** Resolve the Promise with an Object containing `data` and `info` properties instead of resolving only with `data`.
- `callback` **[Function][3]?**

### Examples

Expand All @@ -79,7 +86,7 @@ sharp(input)
.catch(err => { ... });
```

Returns **[Promise][4]<[Buffer][7]>** when no callback is provided
Returns **[Promise][5]<[Buffer][8]>** when no callback is provided

## withMetadata

Expand All @@ -89,8 +96,8 @@ This will also convert to and add a web-friendly sRGB ICC profile.

### Parameters

- `options` **[Object][5]?**
- `options.orientation` **[Number][8]?** value between 1 and 8, used to update the EXIF `Orientation` tag.
- `options` **[Object][6]?**
- `options.orientation` **[Number][9]?** value between 1 and 8, used to update the EXIF `Orientation` tag.

### Examples

Expand All @@ -101,7 +108,7 @@ sharp('input.jpg')
.then(info => { ... });
```

- Throws **[Error][3]** Invalid parameters
- Throws **[Error][4]** Invalid parameters

Returns **Sharp**

Expand All @@ -111,19 +118,19 @@ Use these JPEG options for output image.

### Parameters

- `options` **[Object][5]?** output options
- `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
- `options.progressive` **[Boolean][6]** use progressive (interlace) scan (optional, default `false`)
- `options.chromaSubsampling` **[String][1]** set to '4:4:4' to prevent chroma subsampling when quality <= 90 (optional, default `'4:2:0'`)
- `options.trellisQuantisation` **[Boolean][6]** apply trellis quantisation, requires libvips compiled with support for mozjpeg (optional, default `false`)
- `options.overshootDeringing` **[Boolean][6]** apply overshoot deringing, requires libvips compiled with support for mozjpeg (optional, default `false`)
- `options.optimiseScans` **[Boolean][6]** optimise progressive scans, forces progressive, requires libvips compiled with support for mozjpeg (optional, default `false`)
- `options.optimizeScans` **[Boolean][6]** alternative spelling of optimiseScans (optional, default `false`)
- `options.optimiseCoding` **[Boolean][6]** optimise Huffman coding tables (optional, default `true`)
- `options.optimizeCoding` **[Boolean][6]** alternative spelling of optimiseCoding (optional, default `true`)
- `options.quantisationTable` **[Number][8]** quantization table to use, integer 0-8, requires libvips compiled with support for mozjpeg (optional, default `0`)
- `options.quantizationTable` **[Number][8]** alternative spelling of quantisationTable (optional, default `0`)
- `options.force` **[Boolean][6]** force JPEG output, otherwise attempt to use input format (optional, default `true`)
- `options` **[Object][6]?** output options
- `options.quality` **[Number][9]** quality, integer 1-100 (optional, default `80`)
- `options.progressive` **[Boolean][7]** use progressive (interlace) scan (optional, default `false`)
- `options.chromaSubsampling` **[String][2]** set to '4:4:4' to prevent chroma subsampling when quality <= 90 (optional, default `'4:2:0'`)
- `options.trellisQuantisation` **[Boolean][7]** apply trellis quantisation, requires libvips compiled with support for mozjpeg (optional, default `false`)
- `options.overshootDeringing` **[Boolean][7]** apply overshoot deringing, requires libvips compiled with support for mozjpeg (optional, default `false`)
- `options.optimiseScans` **[Boolean][7]** optimise progressive scans, forces progressive, requires libvips compiled with support for mozjpeg (optional, default `false`)
- `options.optimizeScans` **[Boolean][7]** alternative spelling of optimiseScans (optional, default `false`)
- `options.optimiseCoding` **[Boolean][7]** optimise Huffman coding tables (optional, default `true`)
- `options.optimizeCoding` **[Boolean][7]** alternative spelling of optimiseCoding (optional, default `true`)
- `options.quantisationTable` **[Number][9]** quantization table to use, integer 0-8, requires libvips compiled with support for mozjpeg (optional, default `0`)
- `options.quantizationTable` **[Number][9]** alternative spelling of quantisationTable (optional, default `0`)
- `options.force` **[Boolean][7]** force JPEG output, otherwise attempt to use input format (optional, default `true`)

### Examples

Expand All @@ -137,7 +144,7 @@ const data = await sharp(input)
.toBuffer();
```

- Throws **[Error][3]** Invalid options
- Throws **[Error][4]** Invalid options

Returns **Sharp**

Expand All @@ -150,16 +157,16 @@ Indexed PNG input at 1, 2 or 4 bits per pixel is converted to 8 bits per pixel.

### Parameters

- `options` **[Object][5]?**
- `options.progressive` **[Boolean][6]** use progressive (interlace) scan (optional, default `false`)
- `options.compressionLevel` **[Number][8]** zlib compression level, 0-9 (optional, default `9`)
- `options.adaptiveFiltering` **[Boolean][6]** use adaptive row filtering (optional, default `false`)
- `options.palette` **[Boolean][6]** quantise to a palette-based image with alpha transparency support, requires libvips compiled with support for libimagequant (optional, default `false`)
- `options.quality` **[Number][8]** use the lowest number of colours needed to achieve given quality, requires libvips compiled with support for libimagequant (optional, default `100`)
- `options.colours` **[Number][8]** maximum number of palette entries, requires libvips compiled with support for libimagequant (optional, default `256`)
- `options.colors` **[Number][8]** alternative spelling of `options.colours`, requires libvips compiled with support for libimagequant (optional, default `256`)
- `options.dither` **[Number][8]** level of Floyd-Steinberg error diffusion, requires libvips compiled with support for libimagequant (optional, default `1.0`)
- `options.force` **[Boolean][6]** force PNG output, otherwise attempt to use input format (optional, default `true`)
- `options` **[Object][6]?**
- `options.progressive` **[Boolean][7]** use progressive (interlace) scan (optional, default `false`)
- `options.compressionLevel` **[Number][9]** zlib compression level, 0-9 (optional, default `9`)
- `options.adaptiveFiltering` **[Boolean][7]** use adaptive row filtering (optional, default `false`)
- `options.palette` **[Boolean][7]** quantise to a palette-based image with alpha transparency support, requires libvips compiled with support for libimagequant (optional, default `false`)
- `options.quality` **[Number][9]** use the lowest number of colours needed to achieve given quality, requires libvips compiled with support for libimagequant (optional, default `100`)
- `options.colours` **[Number][9]** maximum number of palette entries, requires libvips compiled with support for libimagequant (optional, default `256`)
- `options.colors` **[Number][9]** alternative spelling of `options.colours`, requires libvips compiled with support for libimagequant (optional, default `256`)
- `options.dither` **[Number][9]** level of Floyd-Steinberg error diffusion, requires libvips compiled with support for libimagequant (optional, default `1.0`)
- `options.force` **[Boolean][7]** force PNG output, otherwise attempt to use input format (optional, default `true`)

### Examples

Expand All @@ -170,7 +177,7 @@ const data = await sharp(input)
.toBuffer();
```

- Throws **[Error][3]** Invalid options
- Throws **[Error][4]** Invalid options

Returns **Sharp**

Expand All @@ -180,14 +187,14 @@ Use these WebP options for output image.

### Parameters

- `options` **[Object][5]?** output options
- `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
- `options.alphaQuality` **[Number][8]** quality of alpha layer, integer 0-100 (optional, default `100`)
- `options.lossless` **[Boolean][6]** use lossless compression mode (optional, default `false`)
- `options.nearLossless` **[Boolean][6]** use near_lossless compression mode (optional, default `false`)
- `options.smartSubsample` **[Boolean][6]** use high quality chroma subsampling (optional, default `false`)
- `options.reductionEffort` **[Number][8]** level of CPU effort to reduce file size, integer 0-6 (optional, default `4`)
- `options.force` **[Boolean][6]** force WebP output, otherwise attempt to use input format (optional, default `true`)
- `options` **[Object][6]?** output options
- `options.quality` **[Number][9]** quality, integer 1-100 (optional, default `80`)
- `options.alphaQuality` **[Number][9]** quality of alpha layer, integer 0-100 (optional, default `100`)
- `options.lossless` **[Boolean][7]** use lossless compression mode (optional, default `false`)
- `options.nearLossless` **[Boolean][7]** use near_lossless compression mode (optional, default `false`)
- `options.smartSubsample` **[Boolean][7]** use high quality chroma subsampling (optional, default `false`)
- `options.reductionEffort` **[Number][9]** level of CPU effort to reduce file size, integer 0-6 (optional, default `4`)
- `options.force` **[Boolean][7]** force WebP output, otherwise attempt to use input format (optional, default `true`)

### Examples

Expand All @@ -198,7 +205,7 @@ const data = await sharp(input)
.toBuffer();
```

- Throws **[Error][3]** Invalid options
- Throws **[Error][4]** Invalid options

Returns **Sharp**

Expand All @@ -208,18 +215,18 @@ Use these TIFF options for output image.

### Parameters

- `options` **[Object][5]?** output options
- `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
- `options.force` **[Boolean][6]** force TIFF output, otherwise attempt to use input format (optional, default `true`)
- `options.compression` **[Boolean][6]** compression options: lzw, deflate, jpeg, ccittfax4 (optional, default `'jpeg'`)
- `options.predictor` **[Boolean][6]** compression predictor options: none, horizontal, float (optional, default `'horizontal'`)
- `options.pyramid` **[Boolean][6]** write an image pyramid (optional, default `false`)
- `options.tile` **[Boolean][6]** write a tiled tiff (optional, default `false`)
- `options.tileWidth` **[Boolean][6]** horizontal tile size (optional, default `256`)
- `options.tileHeight` **[Boolean][6]** vertical tile size (optional, default `256`)
- `options.xres` **[Number][8]** horizontal resolution in pixels/mm (optional, default `1.0`)
- `options.yres` **[Number][8]** vertical resolution in pixels/mm (optional, default `1.0`)
- `options.squash` **[Boolean][6]** squash 8-bit images down to 1 bit (optional, default `false`)
- `options` **[Object][6]?** output options
- `options.quality` **[Number][9]** quality, integer 1-100 (optional, default `80`)
- `options.force` **[Boolean][7]** force TIFF output, otherwise attempt to use input format (optional, default `true`)
- `options.compression` **[Boolean][7]** compression options: lzw, deflate, jpeg, ccittfax4 (optional, default `'jpeg'`)
- `options.predictor` **[Boolean][7]** compression predictor options: none, horizontal, float (optional, default `'horizontal'`)
- `options.pyramid` **[Boolean][7]** write an image pyramid (optional, default `false`)
- `options.tile` **[Boolean][7]** write a tiled tiff (optional, default `false`)
- `options.tileWidth` **[Boolean][7]** horizontal tile size (optional, default `256`)
- `options.tileHeight` **[Boolean][7]** vertical tile size (optional, default `256`)
- `options.xres` **[Number][9]** horizontal resolution in pixels/mm (optional, default `1.0`)
- `options.yres` **[Number][9]** vertical resolution in pixels/mm (optional, default `1.0`)
- `options.squash` **[Boolean][7]** squash 8-bit images down to 1 bit (optional, default `false`)

### Examples

Expand All @@ -234,7 +241,7 @@ sharp('input.svg')
.then(info => { ... });
```

- Throws **[Error][3]** Invalid options
- Throws **[Error][4]** Invalid options

Returns **Sharp**

Expand All @@ -251,13 +258,13 @@ Most versions of libheif support only the patent-encumbered HEVC compression for

### Parameters

- `options` **[Object][5]?** output options
- `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
- `options.compression` **[Boolean][6]** compression format: hevc, avc, jpeg, av1 (optional, default `'hevc'`)
- `options.lossless` **[Boolean][6]** use lossless compression (optional, default `false`)
- `options` **[Object][6]?** output options
- `options.quality` **[Number][9]** quality, integer 1-100 (optional, default `80`)
- `options.compression` **[Boolean][7]** compression format: hevc, avc, jpeg, av1 (optional, default `'hevc'`)
- `options.lossless` **[Boolean][7]** use lossless compression (optional, default `false`)


- Throws **[Error][3]** Invalid options
- Throws **[Error][4]** Invalid options

Returns **Sharp**

Expand All @@ -282,8 +289,8 @@ Force output to a given format.

### Parameters

- `format` **([String][1] \| [Object][5])** as a String or an Object with an 'id' attribute
- `options` **[Object][5]** output options
- `format` **([String][2] \| [Object][6])** as a String or an Object with an 'id' attribute
- `options` **[Object][6]** output options

### Examples

Expand All @@ -294,7 +301,7 @@ const data = await sharp(input)
.toBuffer();
```

- Throws **[Error][3]** unsupported format or options
- Throws **[Error][4]** unsupported format or options

Returns **Sharp**

Expand All @@ -308,14 +315,14 @@ Warning: multiple sharp instances concurrently producing tile output can expose

### Parameters

- `options` **[Object][5]?**
- `options.size` **[Number][8]** tile size in pixels, a value between 1 and 8192. (optional, default `256`)
- `options.overlap` **[Number][8]** tile overlap in pixels, a value between 0 and 8192. (optional, default `0`)
- `options.angle` **[Number][8]** tile angle of rotation, must be a multiple of 90. (optional, default `0`)
- `options.depth` **[String][1]?** how deep to make the pyramid, possible values are `onepixel`, `onetile` or `one`, default based on layout.
- `options.skipBlanks` **[Number][8]** threshold to skip tile generation, a value 0 - 255 for 8-bit images or 0 - 65535 for 16-bit images (optional, default `-1`)
- `options.container` **[String][1]** tile container, with value `fs` (filesystem) or `zip` (compressed file). (optional, default `'fs'`)
- `options.layout` **[String][1]** filesystem layout, possible values are `dz`, `zoomify` or `google`. (optional, default `'dz'`)
- `options` **[Object][6]?**
- `options.size` **[Number][9]** tile size in pixels, a value between 1 and 8192. (optional, default `256`)
- `options.overlap` **[Number][9]** tile overlap in pixels, a value between 0 and 8192. (optional, default `0`)
- `options.angle` **[Number][9]** tile angle of rotation, must be a multiple of 90. (optional, default `0`)
- `options.depth` **[String][2]?** how deep to make the pyramid, possible values are `onepixel`, `onetile` or `one`, default based on layout.
- `options.skipBlanks` **[Number][9]** threshold to skip tile generation, a value 0 - 255 for 8-bit images or 0 - 65535 for 16-bit images (optional, default `-1`)
- `options.container` **[String][2]** tile container, with value `fs` (filesystem) or `zip` (compressed file). (optional, default `'fs'`)
- `options.layout` **[String][2]** filesystem layout, possible values are `dz`, `zoomify` or `google`. (optional, default `'dz'`)

### Examples

Expand All @@ -331,22 +338,24 @@ sharp('input.tiff')
});
```

- Throws **[Error][3]** Invalid parameters
- Throws **[Error][4]** Invalid parameters

Returns **Sharp**

[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
[1]: #withmetadata

[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function

[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise

[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

[7]: https://nodejs.org/api/buffer.html
[8]: https://nodejs.org/api/buffer.html

[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
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