Standardization of reproduction of Remote Sensing
images and its quality control system
Zhang Qingpu
Research Institute of Surveying and Mapping
Beijing, China
Abstract
In this paper based on the principles of color reproduction and spectrophotometry,the distinguishing features of reproduction to remote sensing , geometric of color scanners and the standardization of systematic approach of reproduction are described.
The distinguising features of reproduction to Remote Sensing images1
Over the recent years, cartographers and geographers in the world have produced a lot of photomaps using remote sensing images .Compared with color reproduction in conventional Graphic Arts, reproduction of remote sensing images has its own distinguishing features which may be summarized as follows:
- The system for reproduction must provide high geometric accuracy.
- It is important to obtain more image details on printed sheets rather than accurate color rendition.
- The reproduction approach must have flexibility because of particular requirements for different originals.
The analysis of geometric accuracy of color scanners
It is known that in process of reproduction there are a lot of factors influencing the accuracy of scanning systems, such as lenses distortion, film distortion, magnification, tolerance of the optical and mechanical construction of scanners working conditions and so on. For practical purposes we have confined ourselves to examination of the total accuracy of scanning systems only instead of analyzing every factor separately. The objective of examinations is:
- To check if scanners have the same distortion in both vertical and horizontal directions.
- To determine whether the standard deviations of the scanning systems are acceptable.
- To detect if there is any spherical distortion in scanning systems.
To this end we prepared a line original in polyester base. To determine relationship between magnification indexes of scanning systems and the accuracy of reproduction we scanned the original line at different scanners. Applying the principles of the least square method the accuracy of scanning systems was calculated .The results are shown in Table 1.
Table 1
|
Scanners | Mag. |
(D) max.(mm) |
g(mm) |
SHV | dHV |
| (DH) |
(DV) |
gH |
gV |
gHV |
| DC-400B |
1 | -0.10 | -0.07 | ± 0.06 | ±0.04
| ± 0.05 | -0.03 | ±0.04 |
| 2 | -0.15 | -0.06 | ± 0.11 | ±0.04 | ± 0.08 |
-0.06 | ±0.05 |
| 4 | -0.22 | -0.08 | ± 0.17 |
± 0.17 | ± 0.13 | -0.08 | ±0.11 |
| 6 | -0.09 | -0.10 | ± 0.08 | ±0.10 | ± 0.09 |
0
| ±0.09 |
| M-550 |
1 | -0.23 | -0.09 | ± 0.13 | ± 0.04 | ±0.10 |
-0.06 | ± 0.08 |
| 2 | -0.29 | -0.05 | ± 0.26 | ± 0.03 |
±0.19 | -0.12 | ± 0.14 |
| 4 | -0.35 | -0.13 | ±0.13 | ± 0.30 | ± 0.09 | -0.12 | ±0.19 |
| 8 | -0.73 | 0.20 | ± 0.56 | ± 0.05 | ± 0.40 | -0.22 | ±0.33 |
In Table 1 (
D) max maximum error at n measured lines
(
D) H-error in horizontal direction,
(
D) V- error in vertical direction,
g-root mean square error,
gHV -root mean square error in horizontal and vertical directions,
SHV systematic error in both horizontal land vertical directions,
dHV - Standard error in both horizontal and vertical directions,
