The technique that we used throughout the book is simple, robust, and straightforward. For the story that we want you to enjoy, there are just three rules for interpretation of the Difference FCC images.

• At least 90% of most scenes will show no landcover change, despite the landcover type, and therefore will appear as a neutral grey colour.
• Seasonal changes in the vigour or greenness of landcover between the two dates will be either reddish colours - indicating that the first date was greener than the second date - or bluish colours, indicating that the second date was greener than the first.
• Significant changes in landcover structure and abundance, such as clearing or regrowth, will appear as either dark tones, indicating that the landcover at the second date is less than the first date (landcover loss), or in white tones indicating that the landcover at the second date is greater than the first (landcover increase).

These rules can be summarised into five general colours (spectral classes) that we can see in the Difference FCC image:

grey	no change
red	loss of greenness
blue	increase in greenness
black	loss of landcover amount
white	gain in landcover amount

These same interpretation rules will apply to every Difference FCC image displayed in this book. You may find it useful to bookmark this page for future reference.

Remember - the interpretation of the colours in the Difference FCC image is slightly different from those of a standard or normal FCC image. At this point, you may want to reread the earlier chapter on the nature of satellite images.