The .ddr file stores size and geolocation of the image. The .meta file stores the metadata such as satellite location, acquisition time etc. In order to get information about image size, geolocation or pixel size, you need to view the .ddr file. Use the dspddr program to do this. You can also use the image info menu item of sarview.
CEOS images store vast quantities of data in their .L files.
Image conversion of complex data Complex data are difficult to visualize. They have first to be converted into a floating point amplitude and phase. The ASF software tools support a variety of image format for importing and exporting data. This maps 200 m elevation to black and 2400 m elevation to white as it converts to bytes.