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102 lines
4.4 KiB
Markdown
102 lines
4.4 KiB
Markdown
<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
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## metadata
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Fast access to (uncached) image metadata without decoding any compressed image data.
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A `Promise` is returned when `callback` is not provided.
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- `format`: Name of decoder used to decompress image data e.g. `jpeg`, `png`, `webp`, `gif`, `svg`
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- `size`: Total size of image in bytes, for Stream and Buffer input only
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- `width`: Number of pixels wide (EXIF orientation is not taken into consideration)
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- `height`: Number of pixels high (EXIF orientation is not taken into consideration)
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- `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...][1]
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- `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
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- `depth`: Name of pixel depth format e.g. `uchar`, `char`, `ushort`, `float` [...][2]
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- `density`: Number of pixels per inch (DPI), if present
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- `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
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- `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
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- `pages`: Number of pages/frames contained within the image, with support for TIFF, HEIF, PDF, animated GIF and animated WebP
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- `pageHeight`: Number of pixels high each page in a multi-page image will be.
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- `loop`: Number of times to loop an animated image, zero refers to a continuous loop.
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- `delay`: Delay in ms between each page in an animated image, provided as an array of integers.
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- `pagePrimary`: Number of the primary page in a HEIF image
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- `hasProfile`: Boolean indicating the presence of an embedded ICC profile
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- `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
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- `orientation`: Number value of the EXIF Orientation header, if present
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- `exif`: Buffer containing raw EXIF data, if present
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- `icc`: Buffer containing raw [ICC][3] profile data, if present
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- `iptc`: Buffer containing raw IPTC data, if present
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- `xmp`: Buffer containing raw XMP data, if present
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- `tifftagPhotoshop`: Buffer containing raw TIFFTAG_PHOTOSHOP data, if present
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### Parameters
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- `callback` **[Function][4]?** called with the arguments `(err, metadata)`
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### Examples
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```javascript
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const image = sharp(inputJpg);
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image
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.metadata()
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.then(function(metadata) {
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return image
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.resize(Math.round(metadata.width / 2))
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.webp()
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.toBuffer();
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})
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.then(function(data) {
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// data contains a WebP image half the width and height of the original JPEG
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});
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```
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Returns **([Promise][5]<[Object][6]> | Sharp)**
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## stats
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Access to pixel-derived image statistics for every channel in the image.
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A `Promise` is returned when `callback` is not provided.
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- `channels`: Array of channel statistics for each channel in the image. Each channel statistic contains
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- `min` (minimum value in the channel)
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- `max` (maximum value in the channel)
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- `sum` (sum of all values in a channel)
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- `squaresSum` (sum of squared values in a channel)
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- `mean` (mean of the values in a channel)
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- `stdev` (standard deviation for the values in a channel)
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- `minX` (x-coordinate of one of the pixel where the minimum lies)
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- `minY` (y-coordinate of one of the pixel where the minimum lies)
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- `maxX` (x-coordinate of one of the pixel where the maximum lies)
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- `maxY` (y-coordinate of one of the pixel where the maximum lies)
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- `isOpaque`: Value to identify if the image is opaque or transparent, based on the presence and use of alpha channel
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- `entropy`: Histogram-based estimation of greyscale entropy, discarding alpha channel if any (experimental)
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### Parameters
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- `callback` **[Function][4]?** called with the arguments `(err, stats)`
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### Examples
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```javascript
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const image = sharp(inputJpg);
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image
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.stats()
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.then(function(stats) {
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// stats contains the channel-wise statistics array and the isOpaque value
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});
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```
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Returns **[Promise][5]<[Object][6]>**
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[1]: https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L636
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[2]: https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L672
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[3]: https://www.npmjs.com/package/icc
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[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
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[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
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[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
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