📄 frmt_jpeg.html
字号:
<html><head><title>JPEG -- JPEG JFIF File Format</title></head><body bgcolor="#ffffff"><h1>JPEG -- JPEG JFIF File Format</h1>The JPEG JFIF format is supported for reading, and batch writing, but notupdate in place. JPEG files are represented as one band (greyscale) or three band (RGB) datasets with Byte valued bands.<p>There is currently no support for georeferencing information or metadata forJPEG files. But if an ESRI world file exists with the .wld or .jgw suffixes,it will be read and used to establish the geotransform for the image. Overviewscan be built for JPEG files as an external .ovr file.<p>The GDAL JPEG Driver is built using the Independent JPEG Group's jpeglibrary. Also note that the GeoTIFF driver supports tiled TIFF with JPEGcompressed tiles.<p><h2>Creation Options</h2>JPEG files are created using the "JPEG" driver code. Only Byte band typesare supported, and only 1 and 3 band configurations. JPEG file creationis implemented by the batch (CreateCopy) method. <ul><li> <b>WORLDFILE=YES</b>: Force the generation of an associated ESRI worldfile (with the extension .wld). <p><li> <b>QUALITY=n</b>: By default the quality flag is set to 75, but thisoption can be used to select other values. Values must be in therange 10-100. Low values result in higher compression ratios, but poorerimage quality. Values above 95 are not meaningfully better quality butcan but substantially larger.<p><li> <b>PROGRESSIVE=ON</b>: Enabled generation of progressive jpegs. In somecases these will display a reduced resolution image in viewers such asNetscape, and Internet Explorer, before the full file has been downloaded.However, some applications cannot read progressive jpegs at all. GDAL canread progressive jpegs, but takes no advantage of their progressive nature.<p></ul>See Also:<p><ul><li> <a href="http://www.ijg.org/">Independent JPEG Group</a></ul></body></html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -