Real Time Tone Mapping - Eine Evaluierung farbgetreuer Verfahren zur Luminanzkompression

Die neusten Fortschritte im Bereich Real Time Rendering ermög-lichen virtuelle Produktionsabläufe in weiten Teilen der Industrie. Diese Vorgehensweise setzt latenzfreies Arbeiten und eine akkurate Erscheinung voraus. Daher empfiehlt sich die Verwendung von HDR-Rendering für fotorealistische Ergebnisse und Tone Mapping für die passende Darstellung. Gleichwohl gibt es bisher nur wenige Publikationen, die sich mit echtzeitfähigem Tone Mapping beschäftigen. Zudem tendieren Tone Mapping Operatoren dazu, Farberscheinungseffekte zu erzeugen, die zu einer Diskrepanz zwischen dargestelltem und realem Produkt führen. Deshalb werden in dieser Thesis sieben Tone Mapping Operatoren bewertet, die unterschiedliche Ansätze zur Farbkorrektur beinhalten. Sie werden als Fragment Shader implementiert, um Echtzeitverarbeitung zu realisieren. Zusätzlich wird ihre Performance und die subjektive Akkuratesse der Ergebnisse gemessen. Im Ergebnis schneidet der FilmicTMO als global arbeitender Sigmoid-Operator am besten ab und wird für die weitere Verwendung empfohlen.Recent advances in real time rendering enable virtual production pipelines in a broad range of industries. These pipelines require a fast, latency-free handling in addition to the accurate appearance of results. This suggests the use of HDR rendering for photorealistic results and a tone mapping operator for a matched display. However, tone mapping of real time rendering has not been the focus of many publications to this day. Further more, tone mapping tends to cause image appearance effects, which leads to a change in the perception of colors and therefore a discrepancy between displayed and real world products. For this purpose, seven tone mapping operators with different approaches of color correction are evaluated in this thesis. They are implemented as fragment shader to realise real time processing. In addition, their performance and subjective accuracy is measured. As a result, the FilmicTMO as global sigmoid-based operator proceeds best and can be recommended for future work

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..

Calibrated Image Appearance Reproduction

Managing the appearance of images across different display environments is a difficult problem, exacerbated by the proliferation of high dynamic range imaging technologies. Tone reproduction is often limited to luminance adjustment and is rarely calibrated against psychophysical data, while color appearance modeling addresses color reproduction in a calibrated manner, albeit over a limited luminance range. Only a few image appearance models bridge the gap, borrowing ideas from both areas. Our take on scene reproduction reduces computational complexity with respect to the state-of-the-art, and adds a spatially varying model of lightness perception. The predictive capabilities of the model are validated against all psychophysical data known to us, and visual comparisons show accurate and robust reproduction for challenging high dynamic range scenes