(1) Introduction

Spectral Transformer B742B321 is an advanced utility tool for producing high-quality, natural-colour imagery (equivalent to Landsat bands 3/2/1) from pan-sharpened, false-colour Landsat bands 7/4/2 at 14.25m resolution in NASA GeoCover series.

Medium-resolution, natural-colour Landsat imagery is an excellent and indispensable mapping layer for observing land covers in major virtual globes such as Google Earth and Microsoft Virtual Earth. The input for such global imagery is the enduring GeoCover Landsat series, which is now available in three main forms:

• ~8500 individual scenes with all separate bands at original spatial resolutions (28.5m) after Nearest Neighbour (NN) resampling. Such data are available at USGS GloVis or the Global Land Cover Facility. Spatial resampling schemes (Nearest Neighbour versus Cubic Convolution) used in inputs significantly affect subsequent image fusion and pan-sharpening result. (An illustration is provided here, and pan-sharpening with NN-based inputs is discouraged. Users can explore RGB Image Stretching Tool to produce 28.5m-resolution colour composites without performing pan-sharpening analysis.)

• The same number of individual scenes with pan-sharpened, false-colour bands 7/4/2 at 14.25m spatial resolution: During the initial pan-sharpening analysis, corresponding bands 7/4/2 were resampled with Cubic Convolution (CC) to ensure an outstanding pan-sharpened result. This data source is available from USGS GloVis.

• ~880 colours balanced mosaic tiles made from the above ~8500 pan-sharpened scenes with Landsat false-colour bands 7/4/2. An uncompressed version in a lossless GeoTIFF format became downloadable at USGS GloVis from early June 2007. A lossy compressed version in MrSID format is available from NASA Stennis Space Center.

Spectral Transformer B742B321 analyses pan-sharpened, false-colour Landsat bands 7/4/2 with the lineage of Cubic Convolution resampling (i.e., the above data sources 2 and 3). Both individual scenes and mosaic tiles are acceptable. For un-stretched individual scenes with full dynamic ranges, Spectral Transformer B742B321 includes intelligent, highly-efficient and time-saving image stretching methods; for mosaic tiles with color balancing already applied, B742B321 is also equipped with a number of color templates for false-to-true colour simulations.

This tool is of great potential use since pan-sharpened, 14.25m-resolution, false-colour imagery of Landsat bands 7/4/2 is now available in the public domain. Spectral Transformer B742B321 is the right tool for those who are interested in making visually-appealing and the best global Landsat imagery of its kind, with a full set of options enabling colour preferences and benchmarks.

(2) Command line - A powerful, easy-to-implement DOS command

Usage: b742b321.exe

b742b321.exe <image_source_indicator> <image_stretch_indicator>
<green_colour_coefficient>
<brightness_coefficient>
<in.tif> <out.tif>

Version: 3.0, released 15 July 2008

(3) Features and tutorials

Features list and three brief tutorials: PDF (file size ~1MB)

Colour templates illustrated: PDF (file size ~1MB)