Graphics Reference
In-Depth Information
(a)
(b)
(c)
(d)
Fig. 13.7
The effect of coded exposure to deblur live 30Hz video.
a
To p l e f t
a sample frame with
short integration time minimizes motion blur at the expense of low SNR.
b
Top right
maximizing
the integration time improves SNR at the expense of motion blur.
c
Bottom left
processing applied
to eight subframe images maintains the SNR of (
b
) while giving the deblur performance of (
a
)at
the same 30Hz frame rate.
d
Bottom right
video (
c
) following contrast normalization
13.4.1 High Dynamic Range Video in Low Light Conditions
We show the HDR output using the coded exposure approach described in this
section. The source images shown in Fig.
13.7
were taken from a 30Hz video stream
in limited light with a large aperture and a relatively short integration time. The video
is taken with slow panning motion, which adds to pixel blur with long exposures.
The original video (top left) taken under these conditions thus contains significant
thermal noise from the camera. To improve the SNR with a traditional approach, the
camera exposure can be increased by changing the camera integration time, e.g., to
33.3ms, the frame-rate-limited maximum value (top right). However, large amounts
of motion blur are evident using this approach.
The coded exposure method is generated under the same illumination conditions
and with the same camera motion. The output is at the same 30Hz output frame rate,
which is produced by aligning and combining eight LSR subframe images. Each
LSR image is exposed for one-eighth of the frame-rate-limited integration time (i.e.,
4.17ms). The contrast-enhanced version of this image is shown at bottom right of
Fig.
13.7
, and a decrease in motion blur is evident.
