Image stabilization and detail-preserving contrast enhancement for high-performance camera system

다국어 초록 (Multilingual Abstract)

The goal of this research is to develop algorithms which generate high quality image for high-performance camera system. The proposed methods remove the unintentional camera motion in the input image, and enhance the contrast while preserving the detailed information of the original image.
First, this dissertation introduces a highly precise DIS scheme for a hybrid stabilizing system. The stabilizing system adopts a hybrid method of using both OIS and DIS. In the stabilizing system, OIS prestabilizes the original unstable image using gyro-sensors and the resultant image obtained from OIS is post-stabilized using DIS to remove the residual jitters less than one pixel. The proposed DIS, which is newly designed using CGI, can remove not only translational jitters but also rotational ones simultaneously.
Second, a novel contrast enhancement scheme using DPS is presented in this dissertation. In order to enhance the contrast, the proposed method adopts contrast stretching since the stretching has a low computational complexity and preserves the global contrast of the original. However, the stretching often produces unpleasant images that do not contain clear details by limiting the output dynamic range. To solve this problem, we propose a new contrast stretching method based on GDP that can enhance the local image contrast while preserving the global contrast as well as the image details. The proposed scheme is useful for enhancement of the image which has low contrast such as IR imagery.
Experimental results show that the proposed image enhancement schemes can remove the unintentional camera movement, achieve considerable performance improvement against conventional image enhancement techniques, and outperforms other methods with respect to the visual quality and computational complexity.

목차 (Table of Contents)

• 1 Introduction 1
• 2 Brief Backgrounds 5
• 2.1 Conventional Digital Image Stabilization Methods . . . . . . 5
• 2.2 Conventional Contrast Enhancement Methods . . . . . . . . . 6
• 3 Image Stabilization Algorithm 9
• 3.1 Image Stabilizing System . . . . . . . . . . . . . . . . . . . . 9
• 3.1.1 Pre-stabilization with OIS and Fast Motion Compensation
• . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
• 3.1.2 Post-Stabilization using DIS . . . . . . . . . . . . . . . 11
• 3.1.3 Proposed Digital Image Stabilization . . . . . . . . . . 12
• 4 Contrast Enhancement Algorithm 21
• 4.1 Contrast Enhancement Algorithm for IR imagery . . . . . . . 21
• 4.1.1 Contrast Stretching . . . . . . . . . . . . . . . . . . . 23
• iii
• 4.1.2 Proposed Algorithm ; Detail-Preserving Stretching using
• Gradient-Domain Processing . . . . . . . . . . . . 27
• 5 Simulation Results 32
• 5.1 Experimental Results for Proposed DIS . . . . . . . . . . . . 32
• 5.2 Experimental Results for Proposed Contrast Enhancement
• Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
• 6 Conclusions 54