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Sample-Parallel Execution of EBCOT in Fast Mode
JPEG 2000’s most computationally expensive building
block is the Embedded Block Coder with Optimized Truncation
(EBCOT). This paper evaluates how encoders targeting a parallel
architecture such as a GPU can increase their throughput in use
cases where very high data rates are used. The compression
efficiency in the less significant bit-planes is then often poor and
it is beneficial to enable the Selective Arithmetic Coding Bypass
style (fast mode) in order to trade a small loss in compression
efficiency for a reduction of the computational complexity. More
importantly, this style exposes a more finely grained parallelism
that can be exploited to execute the raw coding passes, including
bit-stuffing, in a sample-parallel fashion. For a latency- or
memory critical application that encodes one frame at a time,
EBCOT’s tier-1 is sped up between 1.1x and 2.4x compared to an
optimized GPU-based implementation. When a low GPU
occupancy has already been addressed by encoding multiple
frames in parallel, the throughput can still be improved by 5%
for high-entropy images and 27% for low-entropy images. Best
results are obtained when enabling the fast mode after the fourth
significant bit-plane. For most of the test images the compression
rate is within 1% of the original
RLFC: Random Access Light Field Compression using Key Views and Bounded Integer Encoding
We present a new hierarchical compression scheme for encoding light field
images (LFI) that is suitable for interactive rendering. Our method (RLFC)
exploits redundancies in the light field images by constructing a tree
structure. The top level (root) of the tree captures the common high-level
details across the LFI, and other levels (children) of the tree capture
specific low-level details of the LFI. Our decompressing algorithm corresponds
to tree traversal operations and gathers the values stored at different levels
of the tree. Furthermore, we use bounded integer sequence encoding which
provides random access and fast hardware decoding for compressing the blocks of
children of the tree. We have evaluated our method for 4D two-plane
parameterized light fields. The compression rates vary from 0.08 - 2.5 bits per
pixel (bpp), resulting in compression ratios of around 200:1 to 20:1 for a PSNR
quality of 40 to 50 dB. The decompression times for decoding the blocks of LFI
are 1 - 3 microseconds per channel on an NVIDIA GTX-960 and we can render new
views with a resolution of 512X512 at 200 fps. Our overall scheme is simple to
implement and involves only bit manipulations and integer arithmetic
operations.Comment: Accepted for publication at Symposium on Interactive 3D Graphics and
Games (I3D '19
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