Because the photographic laboratory at the Jet Propulsion Laboratory found it difficult to estimate what were the optimal color renditions of the Iowa landscape for land classification purposes, the Iowa Geological Survey developed its own capability for producing color products from digitally enhanced Landsat data. Research has now shown that efficient production of enhanced images requires full utilization of both computer and photographic enhancement . procedures. Experimental photo-optical enhancement techniques carried out at the EROS Data Center (EDC) for a Landsat-1, 29 August 1972 scene, proved to be more easily interpreted for land classification purposes than the EDC standard color composite. I.f digital processing can be minimized by using photographic enhancement techniques, then costs of enhanced products could be greatly reduced. Perhaps one of the major objectives of computer processing of Landsat data should be to produce high quality cosmetically enhanced (eliminate striping and line drops) data which has a range of digital values that can be completely recorded by film media. If digital processinq can distribute reflectance data throughout the entire recording ranqe of photographic film, then photographic enhancement techniques could be employed cheaply by users familiar with the type of information they wish to extract from the imaqery. Alternatively, if custom enhanced imagery is to be produced for users not having a photographic capability, different enhancements may be tried in an iterative fashion in the photographic laboratory, without having to reprocess digital data in the computer for each iteration. The savings in time and money should be considerable using this approach.
