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Education/Training
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Standardization of reproduction of Remote Sensing
images and its quality control system
Construction of quadrant diagram for reproduction4
After having determined the specification of reproduction, a practical technical approach to reproduction has been set up. We find a quadrant diagram to be a useful tool. This takes account of the specification and influence of viewing conditions on the appearance of transparencies and final printing sheets. The procedure of improved approach can be summarized as follows:
- Original analysis and densitometric measurements. It is necessary to analysis the originals and to determine Dmax, Dmin, ?D and D-. After experiments, we put forward the specification of remote sensing image originals.
- Determination of the scene density range of the original, using the transparency characteristics ( Dmax = 2.4, Dmin = 0.4, ?D = 2.0) and the characteristic curve 1 ( Fig.1 first quadrant), the scene density range of the original subject can be defined . In our case, it is 1.3.
- Determination of the intermediate tone reproduction curve 2 (see Fig.2, quadrant 4). This accommodates the influence of viewing conditions on the appearance of a transparent original and printing conditions.
- Definition of tone reproduction curve 3 (See Fig.1 quadrant 2) . For this purpose, the intermediate tone reproduction curve and characteristic curve are applied.
- Determination of grey balance curves ( Fig. 3 quadrant 3).
- Defining the four separation positives (negatives) required using the grey balance curves and the tone reproduction curve ( Fig. 3 quadrant 1).
- Determination of colour correction amount. Initially colour correction is established applying manufacturer's recommendations, not based on any measurements of ink sets.
- Platemaking, proofing and printing are carried out by the following specification ff reproduction
Conclusion
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Considering the particular requirements, the geometric accuracy of colour scanners is high enough for reproduction of remote sensing images.
- The feasibility of improved quadrant diagram approach for reproduction of remote sensing images is adequate to achieve satisfactory results with scientific and industrial characteristics.
- The research indicates that the important parameters of reproduction may be measured and hence may be controllable within certain tolerance and that the reproduction quality can be assessed objectively.
References
- Sunderland, BHW, TAGA Proceedings, (1979, 67.
- Richard E. Maurer, TAGA Proceedings, (1979), 209
- Yule J.A.C, Principles of colour reproduction, John Wiley & Sons, Inc. (1967), 84.
- Zhang Qingpu, TAGA Proceedings, (1983) 668.
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