• Use case: Download false-color image, then perform on-the-fly computation of the Normalized Difference Vegetation Index (NDVI)
• Dataset: ICGC False-Color Orthoimage; coverage created from GeoTIFF and separate XML file with INSPIRE metadata
• Service used: OGC WCPS
• Notes: The false-color image can be subset and downloaded via WCS GetCoverage or via WCPS. However, WCPS additionally allows pixel-wise computation, such as the NDVI. WCPS queries like this typically are generated automatically by some client or script, users will not notice them.

Next, we do the same with WCPS - just subsetting:

Finally, we compute the NDVI. For better visualization, the NDVI value (normally between -1 and +1) gets added 1 (to be non-negative) and multiplied with 127 (to "stretch" it into the 0 to 255 range of 8-bit grayscale imagery). Cast operations (syntactically: data types in parenthesis, like "(unsigned char)") first force the integer values from the coverage into float for the division, and then into the target format of 8-bit unsigned quantities.