Where frame performs tracking using the image pyramids of multi-resolution and intensity. SIFT is scale
invariant feature transform algorithm [11] which performs extraction of interest points invariant to
translation, rotation, scaling and illumination changes in images. It constructs a Gaussian scale-space
pyramid from the input image and also calculates the gradients and difference-of-Gaussian (DOG) images at
these scales. Interest points are detected at the local extremes within the DOG scale space. With GPU, the
construction of the Gaussian scale space pyramid is accelerated by using fragment programs for separable
Gaussian convolution. These implementations are 1020 times faster than the corresponding optimized CPU
counterparts and enable real-time processing of high resolution video [12]. We can also use the improved
version of parallel SIFT algorithm that provides better performance on multi core platforms [13] and takes
care of following:
1. Load Balancing.
2. Reducing Synchronization Overhead.
3. Removing False Sharing.
4. Applying Thread Affinity.
GPU-based KLT implementation tracks about a thousand features in real-time at 30 Hz on 1024x768
resolution video which is a 20 times improvement over the CPU. It works on both ATI and NVIDIA graphics
cards. The GPU-based SIFT implementation works on NVIDIA cards and extracts about 800 features from
640x480 video at 10Hz which is approximately10 times faster than an optimized CPU implementation [14].
There is another application of feature detection where eye blink detector works on very low contrast images
acquired under near-infrared illumination with GPU[15].Eye blinks are detected inside regions of interest
that are aligned with the subjects eyes at initialization. Alignment is maintained through time by tracking
SIFT feature points that are used to estimate the affine transformation between the initial face pose and the
pose in subsequent frames. Eye blink detection obviously implies prior detection of the eyes in the image of
the subjects face. Here also GPU based implementation of SIFT is used for tracking as provided in the library
Open NVIDIA [16] openvidia.sourceforge.net.
Object detection is the ability to detect and localize objects within an image or a scene [18]. Here also the
features for an object are needed to be extracted. One of the algorithm adopted for object detection is
AdaBoost[17] which further can be run on Graphics Processing Units[18].This particular system can be
evaluated with two face-detection applications which are based on the boosted cascade of classifiers:
Multiple Layers Face Detection (MLFD), and Single Layer Face Detection (SLFD)[18]. It can be observed
that SLFD implementation on GPU performs up to nine times faster than its CPU counterpart. The MLFD, in
the other hand, can be accelerated using the GPU and performs up to three times faster than the CPU[18].In
[19] it is referred further to a method where focus is on the nuclei detection on Hematoxilin eosin stained
colon tissue sample images. It examines that how effectively the algorithms used during the process can be
implemented to data parallel architectures, and is it worth using GPU (Graphic Processing Unit) instead of
the CPU (Central Processing Unit).
368
There
Where frame performs tracking using the image pyramids of multi-resolution and intensity. SIFT is scale
invariant feature transform algorithm [11] which performs extraction of interest points invariant to
translation, rotation, scaling and illumination changes in images. It constructs a Gaussian scale-space
pyramid from the input image and also calculates the gradients and difference-of-Gaussian (DOG) images at
these scales. Interest points are detected at the local extremes within the DOG scale space. With GPU, the
construction of the Gaussian scale space pyramid is accelerated by using fragment programs for separable
Gaussian convolution. These implementations are 1020 times faster than the corresponding optimized CPU
counterparts and enable real-time processing of high resolution video [12]. We can also use the improved
version of parallel SIFT algorithm that provides better performance on multi core platforms [13] and takes
care of following:
1. Load Balancing.
2. Reducing Synchronization Overhead.
3. Removing False Sharing.
4. Applying Thread Affinity.
GPU-based KLT implementation tracks about a thousand features in real-time at 30 Hz on 1024x768
resolution video which is a 20 times improvement over the CPU. It works on both ATI and NVIDIA graphics
cards. The GPU-based SIFT implementation works on NVIDIA cards and extracts about 800 features from
640x480 video at 10Hz which is approximately10 times faster than an optimized CPU implementation [14].
There is another application of feature detection where eye blink detector works on very low contrast images
acquired under near-infrared illumination with GPU[15].Eye blinks are detected inside regions of interest
that are aligned with the subjects eyes at initialization. Alignment is maintained through time by tracking
SIFT feature points that are used to estimate the affine transformation between the initial face pose and the
pose in subsequent frames. Eye blink detection obviously implies prior detection of the eyes in the image of
the subjects face. Here also GPU based implementation of SIFT is used for tracking as provided in the library
Open NVIDIA [16] openvidia.sourceforge.net.
Object detection is the ability to detect and localize objects within an image or a scene [18]. Here also the
features for an object are needed to be extracted. One of the algorithm adopted for object detection is
AdaBoost[17] which further can be run on Graphics Processing Units[18].This particular system can be
evaluated with two face-detection applications which are based on the boosted cascade of classifiers:
Multiple Layers Face Detection (MLFD), and Single Layer Face Detection (SLFD)[18]. It can be observed
that SLFD implementation on GPU performs up to nine times faster than its CPU counterpart. The MLFD, in
the other hand, can be accelerated using the GPU and performs up to three times faster than the CPU[18].In
[19] it is referred further to a method where focus is on the nuclei detection on Hematoxilin eosin stained
colon tissue sample images. It examines that how effectively the algorithms used during the process can be
implemented to data parallel architectures, and is it worth using GPU (Graphic Processing Unit) instead of
the CPU (Central Processing Unit).
368
There
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