1. imageio-ext




The JPEG JFIF format is supported for reading. JPEG files are represented as one band (greyscale) or three band (RGB) datasets with Byte valued bands. The driver will automatically convert images whose color space is YCbCr, CMYK or YCbCrK to RGB, unless GDAL_JPEG_TO_RGB is set to NO (YES is the default). When color space translation to RGB is done, the source color space is indicated in the SOURCE_COLOR_SPACE metedata of the IMAGE_STRUCTURE domain. There is currently no support for georeferencing information or metadata for JPEG files. But if an ESRI world file exists with the .jgw, .jpgw/.jpegw or .wld suffixes, it will be read and used to establish the geotransform for the image. The driver also supports the "zlib compressed mask appended to the file" approach used by a few data providers to add a bitmask to identify pixels that are not valid data. The GDAL JPEG Driver is built using the Independent JPEG Group's jpeg library.