Towards Mobile HDR Video

by Tassio Knop and Alexandre Chapiro,
Done as coursework for graduate course at IMPA given by Luiz Velho - Aug/Dec 2010


The dynamic range of sensors used in digital photography is many times less than that of the human eye. This calls for algorithmic solutions, namely, HDR images/videos.

We have created an application for the Nokia N900 cellphone with the FrankenCamera API that allows us to capture scenes with varying exposure values. These images are then processed by our algorithm, which creates a High Definition Range video, with the same ammount of frames as the original captures and good object movement capture.

Capturing the Frames

An application for the Nokia N900 cellphone with the FrankenCamera API was created to capture sequences of images for the creation of the HDR video. These sequences are comprised of three photographs each, one with a low exposure value, another with the optimal exposure value as given by the autoexposure routine and the last with a greater value. The applications outline is shown below.


Figure 1: Application outline.

A sequence of captured frames is shown below.


Figure 2: Sequence of captured frames.

Creating the HDR video

Once the video with LDR images with varying exposure values is captured, we use Luiz Velho's method in order to create the HDR frames for the new video. This method can be seen on this webpage. One of several HDR construction methods can be chosen. These methods are better explained in our Results Video, which can be seen below. The code for the capture process can be downloaded below as well. The code for the HDR video construction will be available here soon.




Special thanks to all of our friends at the Visgraf Laboratory for their help and support!


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