주관적 화질을 중심으로한 디지털 사진의 화질 연구

Abstract

It has become a difficult decision for the consumers of camera due to the fact that a wide range of digital cameras are available in the market with the aid of increase and development of digital media in general public. The priority in selecting the camera should be for the high image quality within one's personal budget. High image quality, in general, is in the number of pixel or it is discussed with the sizes of the picture files that the camera is able to take. It is questionable that whether an expensive high resolution with high pixel camera is necessary for the general public when the printed photo is a small photo about 6 x 4 inches, and the low resolution monitor is generally used. In other words, when a large size photo is not printed, an expensive high resolution with high pixel camera may not be necessary for the general public. The answer can be found when the photos of different cameras with different number of pixel are compared and evaluated. Therefore, this study compares the quality of Halide photography with the image quality of digital photography and also conducts the comparison experiment of the photography with different pixels. In conclusion, this study brings forth the answer to the previous question and provides the suggestions for the better image quality. Majority of the previous studies on image quality focused on the objective image quality since the value can be easily converted to be quantitative. However, it is unreasonable to say that the actual images depend on the objective image quality. A variety of measurable image quality can be said to be in good image quality mechanically, yet it cannot be necessarily in good image quality through human visual sensation. The visual sensation can include much more than just the categorized identified image quality. Therefore, this study not only uses the detailed objective image quality analysis, but uses a integrated subjective image quality evaluation to compare the digital photography with silver halide photography, and the photography from the digital cameras with different pixels. With a purpose to suggest the proper implementation for effective improvement on the image quality through the visual sensation, the improvement of objective image quality and the evaluation method of subjective image quality have been implemented and the following procedure has been carried out.

1. The objective image quality evaluation and subjective image quality evaluation are examined.

2. There has been previous studies on the image quality evaluation on silver halide with digital photography. Therefore, this study evaluates and analysis with the subjective image quality, and suggests the usefulness of the method. First, the testes' favored lighting ratio is calculated, the sample photographs are gained with over or under exposure from the selected lighting ratio, and then they are compared in pairs to get the distribution chart of good image quality with different exposures. Finally, the digital photographs' and the silver halide photographs' subjective image quality are compared

3. A wide range of digital cameras are introduced, generally with different pixels. Then, is pixel the most influential factor for the image quality? The solution to this question is used to assist the general public's camera selection and it also suggests the importance of the subjective image quality evaluation method in improving the image quality of cameras.

4. The objective image quality of the color characteristics of the digital camera with the use of color patch and gray scare, dynamic range, white balance and more are measured to analyze comparisons of the previous results of subjective image quality. Then, the practical implementation in consideration with visual sensation is suggested to improve image quality with the method of subjective image evaluation .