Graphics Reference
In-Depth Information
to radiance. The final recovered HDR value is a weighted average of the radiance
values of the corresponding pixels across the images. The weights are based on
the reliability of the radiance values. Pixels that have very low contrast or are
close to being saturated are deemed to be less reliable, so they are given lower
weights. The weights themselves come from a continuous reliability estimation
function.
If a pixel in the current frame is considered reliable, i.e., is not too dim or
saturated, its HDR value is computed without the bidirectionally warped image.
That image is only used to fill in regions of the current frame where the pixel
values are too low or considered saturated—the registration used to construct
the previous-to-current and next-to-current images is not reliable in this case. The
final HDR video is obtained by repeating the frame registration and HDR recovery
for each frame in the captured video sequence.
4. Tone mapping. Displaying the high dynamic range video on a low dy-
namic range display requires tone mapping. Compared to still images, the tone
mapping problem for video has the extra challenge of temporal coherence: if the
tone mapping operator varies between frames—as some certainly would—the re-
sults will appear uneven. Flickering of individual pixels is one example of the
kind of artifact that could result. The authors found that the tone mapping algo-
rithm developed by Reinhard et al. [Reinhard et al. 02] worked well when it was
adapted to video.
Search WWH ::




Custom Search