5,350 research outputs found
Exact Histogram Specification Optimized for Structural Similarity
An exact histogram specification (EHS) method modifies its input image to
have a specified histogram. Applications of EHS include image (contrast)
enhancement (e.g., by histogram equalization) and histogram watermarking.
Performing EHS on an image, however, reduces its visual quality. Starting from
the output of a generic EHS method, we maximize the structural similarity index
(SSIM) between the original image (before EHS) and the result of EHS
iteratively. Essential in this process is the computationally simple and
accurate formula we derive for SSIM gradient. As it is based on gradient
ascent, the proposed EHS always converges. Experimental results confirm that
while obtaining the histogram exactly as specified, the proposed method
invariably outperforms the existing methods in terms of visual quality of the
result. The computational complexity of the proposed method is shown to be of
the same order as that of the existing methods.
Index terms: histogram modification, histogram equalization, optimization for
perceptual visual quality, structural similarity gradient ascent, histogram
watermarking, contrast enhancement
Automatic detection of welding defects using the convolutional neural network
Quality control of welded joints is an important step before commissioning of various types of metal structures. The main obstacles to the commissioning of such facilities are the areas where the welded joint deviates from acceptable defective standards. The defects of welded joints include non-welded, foreign inclusions, cracks, pores, etc. The article describes an approach to the detection of the main types of defects of welded joints using a combination of convolutional neural networks and support vector machine methods. Convolutional neural networks are used for primary classification. The support vector machine is used to accurately define defect boundaries. As a preprocessing in our work, we use the methods of morphological filtration. A series of experiments confirms the high efficiency of the proposed method in comparison with pure CNN method for detecting defects
Iteratively Optimized Patch Label Inference Network for Automatic Pavement Disease Detection
We present a novel deep learning framework named the Iteratively Optimized
Patch Label Inference Network (IOPLIN) for automatically detecting various
pavement diseases that are not solely limited to specific ones, such as cracks
and potholes. IOPLIN can be iteratively trained with only the image label via
the Expectation-Maximization Inspired Patch Label Distillation (EMIPLD)
strategy, and accomplish this task well by inferring the labels of patches from
the pavement images. IOPLIN enjoys many desirable properties over the
state-of-the-art single branch CNN models such as GoogLeNet and EfficientNet.
It is able to handle images in different resolutions, and sufficiently utilize
image information particularly for the high-resolution ones, since IOPLIN
extracts the visual features from unrevised image patches instead of the
resized entire image. Moreover, it can roughly localize the pavement distress
without using any prior localization information in the training phase. In
order to better evaluate the effectiveness of our method in practice, we
construct a large-scale Bituminous Pavement Disease Detection dataset named
CQU-BPDD consisting of 60,059 high-resolution pavement images, which are
acquired from different areas at different times. Extensive results on this
dataset demonstrate the superiority of IOPLIN over the state-of-the-art image
classification approaches in automatic pavement disease detection. The source
codes of IOPLIN are released on \url{https://github.com/DearCaat/ioplin}.Comment: Revision on IEEE Trans on IT
An Improved Approach for Contrast Enhancement of Spinal Cord Images based on Multiscale Retinex Algorithm
This paper presents a new approach for contrast enhancement of spinal cord
medical images based on multirate scheme incorporated into multiscale retinex
algorithm. The proposed work here uses HSV color space, since HSV color space
separates color details from intensity. The enhancement of medical image is
achieved by down sampling the original image into five versions, namely, tiny,
small, medium, fine, and normal scale. This is due to the fact that the each
versions of the image when independently enhanced and reconstructed results in
enormous improvement in the visual quality. Further, the contrast stretching
and MultiScale Retinex (MSR) techniques are exploited in order to enhance each
of the scaled version of the image. Finally, the enhanced image is obtained by
combining each of these scales in an efficient way to obtain the composite
enhanced image. The efficiency of the proposed algorithm is validated by using
a wavelet energy metric in the wavelet domain. Reconstructed image using
proposed method highlights the details (edges and tissues), reduces image noise
(Gaussian and Speckle) and improves the overall contrast. The proposed
algorithm also enhances sharp edges of the tissue surrounding the spinal cord
regions which is useful for diagnosis of spinal cord lesions. Elaborated
experiments are conducted on several medical images and results presented show
that the enhanced medical pictures are of good quality and is found to be
better compared with other researcher methods.Comment: 13 pages, 6 figures, International Journal of Imaging and Robotics.
arXiv admin note: text overlap with arXiv:1406.571
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