The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
-2 XS 
a 20 m 
Array 
satellite 
mission 
' . In 
imagery 
1 mode of 
25 m were 
SPOT-2 
14/05/2006 
HRV/HRG 
20m 
60 km 
L29.6 
were pre 
filter 
sized 
3x3 one 
level. In 
spatial 
in 
for 
effects of 
image by 
root mean 
scale 
for the 
namely 
and 
Saturation 
image are 
frequency 
image and 
and Van 
-correlated 
of the 
DWT concept based transformation of high resolution image 
using wavelet to four portions that three of them have high 
frequency and the one has low frequency. Multispectral image 
is resampled to a size that low frequency portion of the high- 
resolution image has. Low frequency of high resolution images 
are replaced by resampled multispectral images. An inverse 
wavelet transformation is done for the three newly replaced 
images. These three images combined to one fused image. The 
fused image keeps in the high spatial resolution with the 
spectral information of the original multi-spectral image (Shi et 
al,2005). 
The HPF fuses both spectral and spatial information with the 
band-addition approach. Edge information is extracted from 
high resolution image and added pixel by pixel basis to the low 
resolution one. High frequency component of the high 
resolution image is concerned to spatial information. High pass 
filter of the high resolution image corresponds to high 
frequency component. In conclusion adding filter to the low 
resolution band, spatial information content of the high 
resolution image replace and will be seen in the fused image 
(Bethune et al., 1998). 
In this study pre-processed images were fused. 3 bands of 
SPOT images were merged with each RADARSAT and 
PALSAR images. Resulting fused images were resampled to 
the higher resolution of SAR images as 8m x 8m. 
3.4 Quality Assessment 
In order to evaluate the advanced spectral quality of the fused 
images, SPOT XS image is compared with the produced fused 
images. Assessment analyses for each of PALSAR-SPOT fused 
image and RADARSAT-SPOT fused image determined. 
Performing the increased interpretation capabilities, spectral 
relationship between the original SPOT image and each of 
fused images were compared to see the advances in spectral 
quality. Bias, Correlation Coefficient (CC), Difference in 
Variance (DIV), Standard Deviation Difference (SDD) and 
Universal Image Quality Index (UIQI) factors were computed 
and compared. 
3.4.1 Visual Comparisons: Visual interpretation was done 
to compare the fused images with SPOT XS. Figure 2 shows the 
different fusion performances of RADARSAT-SPOT and 
PALSAR-SPOT images. Quality of the spatial resolution was 
analysed comparing the features like field borders, roads and 
buildings. In urban areas HPF shows features more detailed. 
The comparison of colour information between the fused 
images and the SPOT XS shows that HPF and DWT give 
similar result. IHS has the worst visual quality in both PALSAR 
and RADARSAT fused images. Urban objects and field borders 
are recognised better in all of the PALSAR fused images then 
RADARSAT fused images. 
SPOT XS 
Radarsat-DWT 
PaJsat-DWT 
Radaisat-IHS 
Palsar-IHS 
R&cktsat-HPF 
PaJsar-HPF 
Radarsat-PCA 
Palsar-PCA