8 research outputs found
Laparoscopic Image Recovery and Stereo Matching
Laparoscopic imaging can play a significant role in the minimally invasive surgical procedure. However, laparoscopic images often suffer from insufficient and irregular light sources, specular highlight surfaces, and a lack of depth information. These problems can negatively influence the surgeons during surgery, and lead to erroneous visual tracking and potential surgical risks. Thus, developing effective image-processing algorithms for laparoscopic vision recovery and stereo matching is of significant importance. Most related algorithms are effective on nature images, but less effective on laparoscopic images.
The first purpose of this thesis is to restore low-light laparoscopic vision, where an effective image enhancement method is proposed by identifying different illumination regions and designing the enhancement criteria for desired image quality. This method can enhance the low-light region by reducing noise amplification during the enhancement process. In addition, this thesis also proposes a simplified Retinex optimization method for non-uniform illumination enhancement. By integrating the prior information of the illumination and reflectance into the optimization process, this method can significantly enhance the dark region while preserving naturalness, texture details, and image structures. Moreover, due to the replacement of the total variation term with two -norm terms, the proposed algorithm has a significant computational advantage.
Second, a global optimization method for specular highlight removal from a single laparoscopic image is proposed. This method consists of a modified dichromatic reflection model and a novel diffuse chromaticity estimation technique. Due to utilizing the limited color variation of the laparoscopic image, the estimated diffuse chromaticity can approximate the true diffuse chromaticity, which allows us to effectively remove the specular highlight with texture detail preservation.
Third, a robust edge-preserving stereo matching method is proposed, based on sparse feature matching, left and right illumination equalization, and refined disparity optimization processes. The sparse feature matching and illumination equalization techniques can provide a good disparity map initialization so that our refined disparity optimization can quickly obtain an accurate disparity map. This approach is particularly promising on surgical tool edges, smooth soft tissues, and surfaces with strong specular highlight
Local tone mapping operator for detail preserving reproduction of high dynamic range images.
Opseg osvetljaja koji se javlja u prirodnim scenama uveliko prevazilazi mogućnosti
standardnih uređaja za snimanje i reprodukciju slike. Ljudski vizuelni sistem je
evoluirao, tako da omogući efikasno funkcionisanje i percepciju detalja u uslovima
velike promene osvetljaja. Kako bi se omogućila što realnija reprodukcija slika i video
sadržaja, potrebno je obezbediti mogućnost snimanja i reprodukcije što šireg
dinamičkog opsega osvetljaja. Razvoj tehnika za snimanje je napredovao i danas postoji
mogućnost snimanja celokupnog dinamičkog opsega osvetljaja scene korišćenjem
standardnih senzora. Razvoj displeja je međutim napredovao sporije i većina displeja
koji su danas u upotrebi ima skroman dinamički opseg osvetljaja. Operator za redukciju
dinamičkog opsega predstavlja ključnu komponentu sistema za reprodukciju scena
širokog dinamičkog opsega (HDR), na standardnim displejima nižeg dinamičkog
opsega (LDR)...Light intensity variations in natural scenes greatly exceed the capabillities of standard
imaging and display devices. The human visual system has evolved to deal with these
lightning conditions and enable efficient perception of details. In order to enable
realistic reproduction of natural images and video, it is necessary to develop techniques
and devices for capturing and reproduction of the high dynamic range content.
Capturing techniques have evolved and now it is possible to capture entire dynamic
range of the scene using standard sensors. The development of displays, however, has
progressed more slowly and most of the displays that are used today exhibits modest
dynamic range capabilities. Tone mapping operator is a key component that enables
reproduction of the high dynamic range (HDR) images on the low dynamic range
(LDR) displays..