In this paper, an application is presented which automatically adapts SDTV (Standard Definition Television) sports productions to smaller displays through intelligent cropping and scaling. It crops regions of interest of sports productions based on a smart combination of production metadata and systematic video analysis methods. This approach allows a context-based composition of cropped images. It provides a differentiation between the original SD version of the production and the processed one adapted to the requirements for mobile TV. The system has been comprehensively evaluated by comparing the outcome of the proposed method with manually and statically cropped versions, as well as with non-cropped versions. Envisaged is the integration of the tool in post-production and live workflows.
Cropping and scaling, computer vision, regions of interest, visual attention, global motion estimation.
IntroductionNowadays, broadcasters distribute their services over various channels. In addition to the traditional broadcast via antenna, satellite or cable, content is provided to the viewer via internet streams, podcasts or adapted broadcast systems for mobile devices, the latter of which is a growing and quite promising market.Especially in Korea (T-DMB) and Japan (One-Seg, based on ISDB-T) the mobile TV market is gaining a substantial market-share.Key requirements for the success of mobile TV services are the adaptation of video content for optimal viewing conditions on mobile devices as well as an appropriate video quality. European mobile TV trials have shown that 24 % of users stopped using the service because of quality issues [1]. The study indicates that there is a high demand for made-for-mobile, bite-sized content.Adaptation of content for mobile devices should be more than just a replication of traditional linear TV content. Mobile TV has to attract an audience with new programming and viewing experiences in order to co-exist with traditional TV on stationary receivers. Watching TV on portable devices should be complementary to the trend towards larger displays at home, such as 42" or even 50" flat screen displays. Unfortunately, all too often, identical TV content is presented on the various distribution channels as the generation of specific content for mobile TV 2 is very costly and time consuming for content providers. The creation of different video formats already needs to be implemented on program production level with direct implications on artistic design. Alternatively, content adaption can be performed manually during postproduction which is not feasible for live productions.The proposed work addresses the problem of content adaptation, in particular for mobile TV applications, by means of contextual automatic cropping. The subregion to be displayed on the mobile device is computed by using metadata information available from the broadcaster's production workflow in combination with video analysis methods. The metadata information feeds the adaptation system with a priori knowledge about the content...