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113 lines
5.2 KiB
Markdown
113 lines
5.2 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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* `levels`: Details of each level in a multi-level image provided as an array of objects, requires libvips compiled with support for OpenSlide
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* `subifds`: Number of Sub Image File Directories in an OME-TIFF image
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* `background`: Default background colour, if present, for PNG (bKGD) and GIF images, either an RGB Object or a single greyscale value
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* `compression`: The encoder used to compress an HEIF file, `av1` (AVIF) or `hevc` (HEIC)
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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`: Is the image fully opaque? Will be `true` if the image has no alpha channel or if every pixel is fully opaque.
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* `entropy`: Histogram-based estimation of greyscale entropy, discarding alpha channel if any (experimental)
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* `sharpness`: Estimation of greyscale sharpness based on the standard deviation of a Laplacian convolution, discarding alpha channel if any (experimental)
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* `dominant`: Object containing most dominant sRGB colour based on a 4096-bin 3D histogram (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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```javascript
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const { entropy, sharpness, dominant } = await sharp(input).stats();
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const { r, g, b } = dominant;
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```
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Returns **[Promise][5]<[Object][6]>**
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[1]: https://libvips.github.io/libvips/API/current/VipsImage.html#VipsInterpretation
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[2]: https://libvips.github.io/libvips/API/current/VipsImage.html#VipsBandFormat
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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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