the Helava DSW200 and also the PS1 are not too sensi-
tive in the blue band and one misses about 30% of light
density. This seems to be compensated by a smearing ef-
fect of the green band. That means that the transparency
of the blue filter is too wide and is affected by light from
the green band.
|
1 This is often not noticed as our eyes are not very sensi-
| tive to the blue light and in aerial photographs only few
objects are blue. The situation is different when one
wants to derive an image with more or less natural colours
from a infrared false colour film. Then it is disturbing when
the measured blue band, which corresponds to the green
band in nature, corresponds largely to the neighbouring KE
/ band. It must be admitted that these measurements are
n also very new and will need confirmation, however that
Hu they can contribute for a discussion.
n AB
| 5. CONCLUSIONS Sp:
| Although a lot of studies have already been made with the
n scanners it seems that many aspects still have to be em
Iis studied. We are aware that the discussion here is still lim- spe
n ited to the scanning process and should finally also in- buy
I clude the presentation of the image on a screen and the The
li printing technique. It is hoped that the study of the
OEEPE will initiate a wider discussion and that finally rec- une
ommendations can be given for an overall scanner test. bou
Due to difficulties to obtain the test material in time it was col
fe not possible to do all the planned tests in time. It is the in- The
a tention to continue this study and to complement the pub- It c
i lication gradually. to 1
| futt
References I.
[1] Kólbl, O., Bach, U., 1994, Tone Reproduction of Pho-
tographic Scanners : Geodezja i Kartografia t. XLIII, As
59-77, Poland que
[2] Kólbl, O., Hawawini, J. 1986, Determination of the cus
Modulation Transfer Function for Aerial Cameras un- sul
qm der Flight Conditions. Proceedings Int. Symposium
I ISPRS Comm.l 'Progress in Imaging Sensors' ,
It Stuttgart, pp 565-572.
Tyr
On
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996
