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51 lines
1.8 KiB
HTML
51 lines
1.8 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
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<title>WEBP - WEBP</title>
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</head>
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<body>
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<h1>WEBP - WEBP</h1>
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<p>Starting with GDAL 1.9.0, GDAL can read and write WebP images through the WebP library.</p>
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<p>WebP is a new image format that provides lossy compression for photographic images.
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A WebP file consists of VP8 image data, and a container based on RIFF.</p>
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<p>The driver rely on the Open Source WebP library (BSD licenced). The WebP library (at least in its
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version 0.1) only offers compression and decompression of whole images, so RAM might be a limitation
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when dealing with big images (which are limited to 16383x16383 pixels).</p>
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<p>The WEBP driver supports 3 bands (RGB) images. It also supports 4 bands (RGBA) starting with GDAL 1.10 and libwebp 0.1.4.</p>
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<p>The WEBP driver can be used as the internal format used by the <a href="frmt_rasterlite.html">Rasterlite</a> driver.</p>
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<p>Starting with GDAL 1.10, XMP metadata can be extracted from the file, and will be
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stored as XML raw content in the xml:XMP metadata domain.</p>
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<h2>Creation options</h2>
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Various creation options exists, among them :
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<ul>
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<li><p><b>QUALITY=n</b>: By default the quality flag is set to 75, but this
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option can be used to select other values. Values must be in the
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range 1-100. Low values result in higher compression ratios, but poorer
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image quality. <p></li>
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<li><p><b>LOSSLESS=True/False</b> (GDAL >= 1.10 and libwebp >= 0.1.4):
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By default, lossy compression is used. If set to True,
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lossless compression will be used.<p></li>
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</ul>
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<p>See Also:</p>
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<ul>
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<li><a href="https://developers.google.com/speed/webp/">WebP home page</a></li>
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</ul>
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</body>
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</html>
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