615 - 
4. Analysis of subframes using additive colour techniques. An I 2 S Mini-Addcol 
Viewer was used for this purpose. 
2 
The test area has a size of 3500 km and is contained in ERTS-frame 1028-10200, 
taken on August 20, 1972. The image has zero cloud cover and is of good quality. 
Figure 2 shows band 5 of this frame. For the analysis use was made of 1:1, 000, 000 
scale diapositives supplied by NASA and of 1:250, 000 scale paper prints produced 
by the ITC photographic department. 
The four single bands: green, no. 4 (0.5-0. 6 micrometers), red, no. 5 (0. 6-0.7 
micrometers), infrared no. 6 (0. 7-0. 8 micrometers), and infrared no. 7 (0.8- 
1.1 micrometers), and the colour composite MSS4-5-7, were investigated for 
gross information content. 
It was found that the best single band for geological interpretation was the red 
band (MSS-5). This band has the widest range of tonal values, which permits 
better discrimination of subtle tonal changes associated with changes in lithology. 
Bands 4 and 6 were found to be the least useful. Band 7 was the best band for 
detection of water bodies, which have very dark signatures in this special region. 
Spectral matching by comparing tonal signatures of features in different bands 
was done preferentially by comparison of band 5 with band 7. This proved to be 
the best combination for discrimination of water bodies, green vegetation, and 
bare rock or soil. 
The colour composite MSS 4-5-7 was considered extremely useful because of its 
capability to depict vegetation patterns very clearly and also because of the fact 
that geological units sometimes showed better differentiation due to the addition 
of colour. 
Using the Additive Colour Viewer, various band and filter combinations were 
tried out. It was found that the main capability of the instrument was that it could 
produce images on which the visibility of certain features of the scene was im 
proved. It was not possible to find a combination by which new (previously unde 
tected) features were seen. Also, it was not possible to find a single combination 
by which all features of interest were simultaneously enhanced to an optimal 
degree. 
DISCUSSION OF INTERPRETATION RESULTS 
The annotated sub-frame covering the Montalban test site is shown in Figure 3. 
It represents the final result of an intensive analysis aimed at an optimal infor 
mation extraction. The original mapping scale was 1:250, 000. A summary discus 
sion of the interpretation results will be given below.