D can not be 
rves for high 
differences 
arger for the 
nsities 1.9 - 
aller (3 grey 
' differences 
density (for 
!) show that 
y scale were 
itions within 
grey values 
1e grey scale 
grey level 
) ca. 20 grey 
all scanners 
the ones in 
Horizon had 
larger than 
it the older 
sensitive to 
s plate. 
ogarithm of 
, these plots 
n the means 
AX show as 
one with the 
r curves can 
ess than 45 
"right areas. 
ies) depend 
duce the 12 
1. A gamma 
nsities and 
in 1 has the 
re unknown 
rs is for the 
| maximum 
ch sense for 
to permit a 
isities. 
RIZON 
CUS_I 
-610 
AGE_D16L 
WERLOOK 
Logarithm 
Table 5. Radiometric test with grey scale wedge. Mean and standard deviation of grey values.! 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Agfa Agfa UMAX UMAX Sharp 
Density Horizon? Arcus II Mirage D-16L | PowerLook? JX-610 
Mean | St.D. | Mean | St D. | Mean | StD. | Mean | St D. | Mean | St.D. 
0.05 248.9 10° (2550 -} O1 255.0 1.0.0 125501 00 ; 2100 1.7 
0.2 177.0 17 1992.11.06 | 221.131 24 11 209.51 2.0 161.61 20 
0.35 128.6 1.1 151.4| 1.5 1502 | 18 140.0 1.9 117.2 1.7 
0.51 95.1 0.9 113.7 1.4 | 100.1 1.4 92.6 PS 83.5 1.4 
0.66 74.2 0.9 87.4 1.2 68.5 14 63.5 1:2 60.7 ]:2 
0.8 60.1 0.7 68.3 I 47.9 0.9 44.6 0.9 45.2 1.0 
0.96 48.2 0.7 52.1 1.0 32:5 0.7 30.5 0.7 32.8 0.9 
1.12 38.2 0.7 39.7 0.9 22.0 0.6 20.7 0.6 23.9 0.7 
1.28 29.1 0.8 30.7 0.8 15.3 0.6 14.1 0.5 17.7 0.7 
1.44 21.8 1.2 23.8 0.7 10.7 0.5 9.9 0.4 13.6 0.6 
1.59 15.9 0.7 18.6 0.7 533 0.5 71 0.3 10.9 0.6 
1.75 11.7 1.0 14.9 0.6 5.8 0.4 5.1 0.3 8.9 0.5 
1.9 8.6 1.1 11.5 0.7 4.4 0.5 3.9 0.3 7.6 0.6 
2.05 59 1.4 9.5 0.6 3.5 0.5 3.0 0.1 6.7 0.5 
2:22 3.7 1.1 7.8 0.7 29 0.3 22 0.4 6.0 0.5 
2:37 2.8 0.8 6.4 0.7 2.5 0.5 2.0 0.2 55 0.5 
2:32 2.2 0.9 55 0.7 2.0 0.3 1.6 0.5 5.2 0.5 
2.67 1.8 1.0 4.9 0.7 1.9 0.4 1:2 0.4 5.1 0.5 
2.82 1.4 1d 4.5 0.7 1.8 0.4 14 0.3 4.9 0.5 
2.95 12 1.1 4.2 0.8 1.7 0.5 1.0 0:2 4.8 0.5 
3.09 1.1 1.1 4.0 0.8 1.6 0.5 1.0 0.1 4.7 0.5 
Mean St. D.* 1.0 0.9 0.7 0.7 0.8 
  
  
  
  
  
  
  
  
i Scanning resolution 600 dpi (Mirage 400 dpi), transparency, all scan parameters set automatically. 
2 Density range = 3.0 D, maximum density = 3.3 D. Values slightly worse than those of Horizon Plus. 
3 Density range = 3.0 D, maximum density = 3.2 D. Values slightly worse than those of PowerLook II. 
4 Excluding lowest and highest density which are partly affected by saturation. 
5. CONCLUSIONS 
DTP scanners are the fastest growing segment in the scanner 
market. Improvements in their overall quality, scan format, 
geometric and radiometric resolution and lower prices should be 
expected. However, an improvement in the geometric accuracy of 
the DTP scanners, or the production by DTP scanner 
manufacturers of new scanners specifically for photogrammetric/ 
cartographic applications is not probable. What could be done 
however, is the optional provision of customers with calibration 
patterns and software at an extra cost which could be around 
4,000 to 6,000 SFr. Here we presented a general and simple 
geometric calibration procedure that has been used with various 
scanners and led to an accuracy of 4 - 7 um. In their current state, 
DTP scanners can be used in some photogrammetric tasks. The 
important point is that the user must clearly define the application 
requirements and examine himself whether they (particularly the 
geometric accuracy) can be fulfilled by a given DTP scanner. The 
main problem of DTP scanners regarding image scanning is that 
they lack high geometric accuracy. Improvements on this topic 
will drastically increase the range of their application. For the 
19 
above reasons the developments in the DTP scanners should be 
closely monitored. 
Acknowledgements 
The authors would like to acknowledge the contribution of 
Michele Crosetto and Marc Troller. 
References 
Baltsavias, E., Bill, R., 1994. Scanners - A Survey of Current 
Technology and Future Needs. In: Int’l Archives of Photogram- 
metry and Remote Sensing, Vol. 30, Part 1, pp. 130 - 143. 
Baltsavias, E., 1994a. The Agfa Horizon DTP Scanner - Charac- 
teristics, Testing and Evaluation. In: Int’l Archives of Photo- 
grammetry and Remote Sensing, Vol. 30, Part 1, pp. 171 - 179. 
Baltsavias, E., 1994b. Test and Calibration Procedures for Image 
Scanners. In: Int'] Archives of Photogrammetry and Remote 
Sensing, Vol. 30, Part 1, pp. 163 - 170. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996