6 research outputs found
Hybrid SPF and KD Operator-Based Active Contour Model for Image Segmentation
Image segmentation is a crucial stage of image analysis systems because it detects and extracts regions of interest for further processing, such as image recognition and the image description. However, segmenting images is not always easy because segmentation accuracy depends significantly on image characteristics, such as color, texture, and intensity. Image inhomogeneity profoundly degrades the segmentation performance of segmentation models. This article contributes to image segmentation literature by presenting a hybrid Active Contour Model (ACM) based on a Signed Pressure Force (SPF) function parameterized with a Kernel Difference (KD) operator. An SPF function includes information from both the local and global regions, making the proposed model independent of the initial contour position. The proposed model uses an optimal KD operator parameterized with weight coefficients to capture weak and blurred boundaries of inhomogeneous objects in images. Combined global and local image statistics were computed and added to the proposed energy function to increase the proposed model's sensitivity. The segmentation time complexity of the proposed model was calculated and compared with previous state-of-the-art active contour methods. The results demonstrated the significant superiority of the proposed model over other methods. Furthermore, a quantitative analysis was performed using the mini-MIAS database. Despite the presence of complex inhomogeneity, the proposed model demonstrated the highest segmentation accuracy when compared to other methods
Saliency-Driven Active Contour Model for Image Segmentation
Active contour models have achieved prominent success in the area of image
segmentation, allowing complex objects to be segmented from the background for
further analysis. Existing models can be divided into region-based active
contour models and edge-based active contour models. However, both models use
direct image data to achieve segmentation and face many challenging problems in
terms of the initial contour position, noise sensitivity, local minima and
inefficiency owing to the in-homogeneity of image intensities. The saliency map
of an image changes the image representation, making it more visual and
meaningful. In this study, we propose a novel model that uses the advantages of
a saliency map with local image information (LIF) and overcomes the drawbacks
of previous models. The proposed model is driven by a saliency map of an image
and the local image information to enhance the progress of the active contour
models. In this model, the saliency map of an image is first computed to find
the saliency driven local fitting energy. Then, the saliency-driven local
fitting energy is combined with the LIF model, resulting in a final novel
energy functional. This final energy functional is formulated through a level
set formulation, and regulation terms are added to evolve the contour more
precisely across the object boundaries. The quality of the proposed method was
verified on different synthetic images, real images and publicly available
datasets, including medical images. The image segmentation results, and
quantitative comparisons confirmed the contour initialization independence,
noise insensitivity, and superior segmentation accuracy of the proposed model
in comparison to the other segmentation models
Understanding the neuroprotective effect of tranexamic acid: an exploratory analysis of the CRASH-3 randomised trial
Background: The CRASH-3 trial hypothesised that timely tranexamic acid (TXA) treatment might reduce deaths from intracranial bleeding after traumatic brain injury (TBI). To explore the mechanism of action of TXA in TBI, we examined the timing of its effect on death. Methods: The CRASH-3 trial randomised 9202 patients within 3 h of injury with a GCS score ≤ 12 or intracranial bleeding on CT scan and no significant extracranial bleeding to receive TXA or placebo. We conducted an exploratory analysis of the effects of TXA on all-cause mortality within 24 h of injury and within 28 days, excluding patients with a GCS score of 3 or bilateral unreactive pupils, stratified by severity and country income. We pool data from the CRASH-2 and CRASH-3 trials in a one-step fixed effects individual patient data meta-analysis. Results: There were 7637 patients for analysis after excluding patients with a GCS score of 3 or bilateral unreactive pupils. Of 1112 deaths, 23.3% were within 24 h of injury (early deaths). The risk of early death was reduced with TXA (112 (2.9%) TXA group vs 147 (3.9%) placebo group; risk ratio [RR] RR 0.74, 95% CI 0.58–0.94). There was no evidence of heterogeneity by severity (p = 0.64) or country income (p = 0.68). The risk of death beyond 24 h of injury was similar in the TXA and placebo groups (432 (11.5%) TXA group vs 421 (11.7%) placebo group; RR 0.98, 95% CI 0.69–1.12). The risk of death at 28 days was 14.0% in the TXA group versus 15.1% in the placebo group (544 vs 568 events; RR 0.93, 95% CI 0.83–1.03). When the CRASH-2 and CRASH-3 trial data were pooled, TXA reduced early death (RR 0.78, 95% CI 0.70–0.87) and death within 28 days (RR 0.88, 95% CI 0.82–0.94). Conclusions: Tranexamic acid reduces early deaths in non-moribund TBI patients regardless of TBI severity or country income. The effect of tranexamic acid in patients with isolated TBI is similar to that in polytrauma. Treatment is safe and even severely injured patients appear to benefit when treated soon after injury. Trial registration: ISRCTN15088122, registered on 19 July 2011; NCT01402882, registered on 26 July 2011