6 research outputs found
High frame rate multi-perspective cardiac ultrasound imaging using phased array probes
Ultrasound (US) imaging is used to assess cardiac disease by assessing the geometry and function of the heart utilizing its high spatial and temporal resolution. However, because of physical constraints, drawbacks of US include limited field-of-view, refraction, resolution and contrast anisotropy. These issues cannot be resolved when using a single probe. Here, an interleaved multi-perspective 2-D US imaging system was introduced, aiming at improved imaging of the left ventricle (LV) of the heart by acquiring US data from two separate phased array probes simultaneously at a high frame rate. In an ex-vivo experiment of a beating porcine heart, parasternal long-axis and apical views of the left ventricle were acquired using two phased array probes. Interleaved multi-probe US data were acquired at a frame rate of 170 frames per second (FPS) using diverging wave imaging under 11 angles. Image registration and fusion algorithms were developed to align and fuse the US images from two different probes. First- and second-order speckle statistics were computed to characterize the resulting probability distribution function and point spread function of the multi-probe image data. First-order speckle analysis showed less overlap of the histograms (reduction of 34.4%) and higher contrast-to-noise ratio (CNR, increase of 27.3%) between endocardium and myocardium in the fused images. Autocorrelation results showed an improved and more isotropic resolution for the multi-perspective images (single-perspective: 0.59 mm Γ 0.21 mm, multi-perspective: 0.35 mm Γ 0.18 mm). Moreover, mean gradient (MG) (increase of 74.4%) and entropy (increase of 23.1%) results indicated that image details of the myocardial tissue can be better observed after fusion. To conclude, interleaved multi-perspective high frame rate US imaging was developed and demonstrated in an ex-vivo experimental setup, revealing enlarged field-of-view, and improved image contrast and resolution of cardiac images.</p
Region-Based Image-Fusion Framework for Compressive Imaging
A novel region-based image-fusion framework for compressive imaging (CI) and its implementation scheme are proposed. Unlike previous works on conventional image fusion, we consider both compression capability on sensor side and intelligent understanding of the image contents in the image fusion. Firstly, the compressed sensing theory and normalized cut theory are introduced. Then region-based image-fusion framework for compressive imaging is proposed and its corresponding fusion scheme is constructed. Experiment results demonstrate that the proposed scheme delivers superior performance over traditional compressive image-fusion schemes in terms of both object metrics and visual quality
Multi-Modal Enhancement Techniques for Visibility Improvement of Digital Images
Image enhancement techniques for visibility improvement of 8-bit color digital images based on spatial domain, wavelet transform domain, and multiple image fusion approaches are investigated in this dissertation research.
In the category of spatial domain approach, two enhancement algorithms are developed to deal with problems associated with images captured from scenes with high dynamic ranges. The first technique is based on an illuminance-reflectance (I-R) model of the scene irradiance. The dynamic range compression of the input image is achieved by a nonlinear transformation of the estimated illuminance based on a windowed inverse sigmoid transfer function. A single-scale neighborhood dependent contrast enhancement process is proposed to enhance the high frequency components of the illuminance, which compensates for the contrast degradation of the mid-tone frequency components caused by dynamic range compression. The intensity image obtained by integrating the enhanced illuminance and the extracted reflectance is then converted to a RGB color image through linear color restoration utilizing the color components of the original image. The second technique, named AINDANE, is a two step approach comprised of adaptive luminance enhancement and adaptive contrast enhancement. An image dependent nonlinear transfer function is designed for dynamic range compression and a multiscale image dependent neighborhood approach is developed for contrast enhancement. Real time processing of video streams is realized with the I-R model based technique due to its high speed processing capability while AINDANE produces higher quality enhanced images due to its multi-scale contrast enhancement property. Both the algorithms exhibit balanced luminance, contrast enhancement, higher robustness, and better color consistency when compared with conventional techniques.
In the transform domain approach, wavelet transform based image denoising and contrast enhancement algorithms are developed. The denoising is treated as a maximum a posteriori (MAP) estimator problem; a Bivariate probability density function model is introduced to explore the interlevel dependency among the wavelet coefficients. In addition, an approximate solution to the MAP estimation problem is proposed to avoid the use of complex iterative computations to find a numerical solution. This relatively low complexity image denoising algorithm implemented with dual-tree complex wavelet transform (DT-CWT) produces high quality denoised images
ΠΠ°ΡΠΊΠΎΠ²ΠΎ-ΠΏΡΠ°ΠΊΡΠΈΡΠ½Ρ Π°ΡΠΏΠ΅ΠΊΡΠΈ ΡΡΠ²ΠΎΡΠ΅Π½Π½Ρ ΡΠ΅ΠΏΠ»ΠΎΠ²ΡΠ·ΡΠΉΠ½ΠΈΡ ΡΠΈΡΡΠ΅ΠΌ
Π ΠΎΠ·Π³Π»ΡΠ½ΡΡΠΎ ΡΠΈΡΠΎΠΊΠ΅ ΠΊΠΎΠ»ΠΎ ΠΏΠΈΡΠ°Π½Ρ, ΡΠΊΡ ΠΏΠΎΠ²βΡΠ·Π°Π½Ρ Π· Π°Π½Π°Π»ΡΠ·ΠΎΠΌ Ρ ΡΠΈΠ½ΡΠ΅Π·ΠΎΠΌ ΡΠ΅ΠΏΠ»ΠΎΠ²ΡΠ·ΡΠΉΠ½ΠΈΡ
ΡΠΈΡΡΠ΅ΠΌ ΡΠΏΠΎΡΡΠ΅ΡΠ΅ΠΆΠ΅Π½Π½Ρ (Π’ΠΠ‘Π‘), ΡΠ·Π³ΠΎΠ΄ΠΆΠ΅Π½Π½ΡΠΌ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡΠ² ΡΡ
ΠΎΡΠ½ΠΎΠ²Π½ΠΈΡ
Π±Π»ΠΎΠΊΡΠ², ΠΊΠΎΠ½ΡΡΡΡΡΠ²Π°Π½Π½ΡΠΌ, ΡΠΎΠ·ΡΠΎΠ±ΠΊΠΎΡ ΠΌΠ΅ΡΠΎΠ΄ΡΠ² ΠΏΡΠ΄Π²ΠΈΡΠ΅Π½Π½Ρ Π΅ΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΡΡΠ½ΠΊΡΡΠΎΠ½ΡΠ²Π°Π½Π½Ρ ΡΠ° Π΅ΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΈΠΌ Π²ΠΈΠ·Π½Π°ΡΠ΅Π½Π½ΡΠΌ ΠΎΡΠ½ΠΎΠ²Π½ΠΈΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ Π’ΠΠ‘Π‘.
ΠΠ»Ρ Π½Π°ΡΠΊΠΎΠ²ΠΈΡ
ΡΠ° ΡΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎ-ΡΠ΅Ρ
Π½ΡΡΠ½ΠΈΡ
ΠΏΡΠ°ΡΡΠ²Π½ΠΈΠΊΡΠ², ΡΡΡΠ΄Π΅Π½ΡΡΠ² Π½Π°ΠΏΡΡΠΌΡ ΠΏΡΠ΄Π³ΠΎΡΠΎΠ²ΠΊΠΈ 6.051004 Β«ΠΠΏΡΠΎΡΠ΅Ρ
Π½ΡΠΊΠ°Β»
ΠΠΎΠΌΠΏΠ»Π΅ΠΊΡΡΠ²Π°Π½Π½Ρ ΡΠ½ΡΠΎΡΠΌΠ°ΡΡΡ Π² Π±Π°Π³Π°ΡΠΎΠΊΠ°Π½Π°Π»ΡΠ½ΠΈΡ ΠΎΠΏΡΠΈΠΊΠΎ-Π΅Π»Π΅ΠΊΡΡΠΎΠ½Π½ΠΈΡ ΡΠΈΡΡΠ΅ΠΌΠ°Ρ ΡΠΏΠΎΡΡΠ΅ΡΠ΅ΠΆΠ΅Π½Π½Ρ
Π ΠΎΠ·Π³Π»ΡΠ½ΡΡΠΎ ΠΌΠ΅ΡΠΎΠ΄ΠΈ ΠΏΡΠ΄Π²ΠΈΡΠ΅Π½Π½Ρ Π΅ΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΡΡΠ½ΠΊΡΡΠΎΠ½ΡΠ²Π°Π½Π½Ρ ΠΎΠΏΡΠΈΠΊΠΎ-Π΅Π»Π΅ΠΊΡΡΠΎΠ½Π½ΠΈΡ
ΡΠΈΡΡΠ΅ΠΌ Π²ΡΠ·ΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠΏΠΎΡΡΠ΅ΡΠ΅ΠΆΠ΅Π½Π½Ρ ΡΠ»ΡΡ
ΠΎΠΌ ΠΏΠΎΡΠ΄Π½Π°Π½Π½Ρ ΡΠ½ΡΠΎΡΠΌΠ°ΡΡΡ Π· ΠΊΡΠ»ΡΠΊΠΎΡ
ΡΠΏΠ΅ΠΊΡΡΠ°Π»ΡΠ½ΠΈΡ
ΠΊΠ°Π½Π°Π»ΡΠ². ΠΠ°ΠΏΡΠΎΠΏΠΎΠ½ΠΎΠ²Π°Π½ΠΎ Π½ΠΎΠ²Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΈ ΠΎΠ±ΡΠΎΠ±ΠΊΠΈ Π·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½Ρ ΡΠ° Π½ΠΎΠ²Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΈ ΠΎΡΡΠ½ΠΊΠΈ ΡΠΊΠΎΡΡΡ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ²Π°Π½ΠΈΡ
Π·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½Ρ. ΠΠ°Π²Π΅Π΄Π΅Π½ΠΎ ΠΏΡΠ°ΠΊΡΠΈΡΠ½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΈ Π·Π°ΡΡΠΎΡΡΠ²Π°Π½Π½Ρ ΡΠΎΠ·ΡΠΎΠ±Π»Π΅Π½ΠΈΡ
ΠΌΠ΅ΡΠΎΠ΄ΡΠ².
ΠΠ»Ρ Π½Π°ΡΠΊΠΎΠ²ΠΈΡ
ΡΠ° ΡΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎ-ΡΠ΅Ρ
Π½ΡΡΠ½ΠΈΡ
ΠΏΡΠ°ΡΡΠ²Π½ΠΈΠΊΡΠ², ΡΡΡΠ΄Π΅Π½ΡΡΠ² Π½Π°ΠΏΡΡΠΌΡ ΠΏΡΠ΄Π³ΠΎΡΠΎΠ²ΠΊΠΈ 6.051004 Β«ΠΠΏΡΠΎΡΠ΅Ρ
Π½ΡΠΊΠ°Β»