CoastWatch Data Analysis Tool Help: Exporting to other formats

In this section:

About exporting

Data may be exported to a variety of formats. Image formats such as JPEG and PNG contain color pixel data computed by converting data values to colors using the active enhancement and palette. The output file contains an image similar to the current data view. Data formats such as HDF and binary raster contain one or more grids of 8-bit to 64-bit data values computed directly from the source data. Select File|Export from the menu or click Export on the toolbar to export data.

Image formats

PNG image
A non-lossy compressed image format supported by most web browsers and image manipulation software. PNG has similar data compression characteristics to GIF and additionally supports 24-bit color images.
GIF image
A non-lossy compressed format also supported by most web browsers and image manipulation software. The GIF files produced use LZW compression. Images stored in GIF format are run through a color quantization algorithm to reduce the color map to 256 colors or less. Although file sizes are generally smaller than PNG, image quality may be compromised by the reduced color map.
JPEG image
A lossy compressed format that should be used with caution for images with sharp color lines such as those found in text and annotation graphics. The JPEG format generally achieves higher compression than PNG or GIF resulting in smaller image file sizes.
GeoTIFF image
A flexible image format with support for earth location metadata. Many popular GIS packages handle GeoTIFF images and allow the user to combine a GeoTIFF base map image with other sources of raster and vector data. The GeoTIFF images generated are non-lossy uncompressed image data (unless a compression is specified in the options), and can be much larger than the corresponding PNG, GIF, or JPEG. In general the GeoTIFFs generated are 24-bit colour images, but when no overlays are used or the image color option is set, a special 8-bit paletted image file is generated and comments describing the data value scaling are inserting into the image description tags.
PDF document
A standard document format for high quality publishing developed by Adobe Systems and used for output to a printer via such tools as the Adobe Acrobat Reader. In general, PDF files are slightly larger than the equivalent PNG but retain highly accurate vector graphics components such as lines and fonts.

Data formats

CoastWatch HDF
Hierarchical Data Format (HDF) version 4 with CoastWatch metadata. HDF is a scientific data format used by CoastWatch and others to distribute satellite data. Information and access software may be found at http://hdf.ncsa.uiuc.edu. A description of current CoastWatch metadata standards is available in the CoastWatch Utilities user's guide.
Binary raster
A simple stream of binary data values -- either 8-bit unsigned bytes, 16-bit signed integers, or 32-bit IEEE floating point values. Data values may optionally be scaled to integers using the equation integer = value/factor + offset. Each data variable may be prepended with a 72-bit dimension header: 8-bit dimension count (always 2) with 32-bit row count, 32-bit column count.
Text file
An ASCII text file with latitude, longitude, and data value printed -- one data value per line. Each data variable may be prepended with a 1-line dimension header: dimension count (always 2), row count, column count.
ArcGIS binary grid
A stream of 32-bit IEEE floating point values, ready for input to ESRI's ArcGIS as a binary grid file. A header file may also be created to specify the earth location and other parameters.

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