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Contrast enhancement for mimimum mean brightness error from histogram partitioning
(2009-12-01)
Phanthuna, N.
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Cheevasuvit, F.
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Chitwong, S.
This paper presents the image enhancing using a mean separated histogram equalization method. To provide the minimum mean brightness error after the histogram modification. It separates the input image's histogram into n (n=1,2,3,⋯) groups based on input mean before equalizing them independently. The image initially is separated class by calculated threshold level and each class is histogram equalized to entire image, and gets lowest AMBE (AMBE: Absolute Mean Brightness Error). The result found that AMBE gradually reduces when the separation is increased. Therefore, the error threshold is assigned in order to automatically dividing the original histogram for obtaining the desired AMBE. This process will be applied to remote sensing data by treating each region of histogram independently. Also Tenengrad is employed in order to verify the contrast performance. The image performance is considered higher if its Tenengrad value is larger.
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A fast intensity-hue-saturation fusion approach via principal component analysis for ikonos imagery
(2008-12-01)
Minhayenud, S.
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Chitwong, S.
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Cheevasuvit, F.
To enhance spatial information of low resolution multi-spectral (RGB) image, the intensity-hue-saturation (IHS) approach is perfectly used to fuse the low resolution RGB image and the high resolution panchromatic (Pan) image by replacing intensity component with the high-resolution Pan image. Disadvantage of the mentioned approach is that color of a fused image is changed because the saturation component is changed or spectral of the low resolution RGB image and the high resolution Pan image is different, that is, spectral information of the fused RGB image is distorted. This problem is important for applying the fused image for classification. To solve this problem, in this paper, we employ the principal component analysis (PCA) transformation to extract information from the low resolution RGB image. In procedure of fusion method, the first principal component is used to adjust brightness of the high resolution Pan image. The intensity component from IHS transformation is replaced by the adjusted brightness high-resolution Pan image. The experimental results by using IKONOS imagery show that the proposed approach is better performance than the original IHS methods by improving spectral distortion and still correlating to the Pan image.
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Contrast enhancement of satellite image based on adaptive unsharp masking using wavelet transform
(2006-12-01)
Chitwong, S.
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Phahonyothing, S.
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Nilas, P.
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Cheevasuvit, F.
This paper concerns with a method for unsharp masking for contrast enhancement of satellite image. We employ the nature of wavelet transform that separates the original image into low and high frequency sub-band images as low and high pass filter. Particularly, a number of high frequency sub-band images consist of horizontal, vertical, and diagonal coefficients that contain detail of information. Taking inverse wavelet transform of each sub-band image separately except low frequency one, we have each of high frequency information in horizontal, vertical, and diagonal image. All of them are scaled by the scaling factor in each one separately. Adaptive algorithm is implemented to results the suitable scaling factor to obtain the enhanced image corresponding with the given criterion based on variance of each area smooth and detail area. Experimental results show that our method performs well to high enhance in detail area and low in smooth area.
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Speckle noise reduction using adaptive singular value decomposition in logarithmic domain
(2005-12-01)
Chitwong, S.
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Thongsila, A.
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Intajag, S.
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Nilas, P.
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Cheevasuvit, F.
This paper presents applying the singular value decomposition to reduce speckle noise. Generally, it is used to filter the additive Gaussian noise with zero mean and any variance. Since speckle noise is in multiplicative model, to transform multiplicative model into additive model, we then employ logarithmic transformation. In this paper, speckle noise is generally modeled as Gamma distribution function corresponding with speckle noise of synthetic aperture radar (SAR) imagery applied. All singular value decomposition based filtering processing is in logarithmic domain. Threshold value to determine the effective rank and orders of matrix are adapted as homogeneity analysis. The orders of matrix are consisted of 16 by 16, 8 by 8 and 4 by 4. Normally, the results of the singular value decomposition based filtering after that the filtered matrix is transformed into spatial domain by exponential function is in block-fashion, then blocking effect is occurred. To smooth, the filtered matrix is performed as average filtering by using a number of pixels of 4 by 4 pixels around center of one. Experiments are tested using both simulated image and real image. Signal to noise ratio and equivalent number of looks are employed to evaluate the performance of our method. Our results are good enough when compared with the recent results at which such method is more complex. © 2005 by the American Society for Photogrammetry and Remote Sensing.
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Local area histogram equalization based multispectral image enhancement from clustering using competitive hopfield neural network
(2003-10-01)
Chitwong, S.
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Boonmee, T.
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Cheevasuvit, F.
One of important issues for enhancing image based on local area histogram equalization (LHE) is a clustering or segmenting technique. That is, the more the accuracy of separating image into specified classes is needed, the better the performance of enhancement is. As mentioned objective, in this paper, the competitive Hopfield neural network (CHNN) is then proposed for clustering to the LHE based image enhancement. By using simulated image, standard image and mutispectral image from Landsat 7 satellite, experimental results are shown in both accuracy of clustering and variance of the enhanced image. The criteria for a good enhancement algorithm is that it can give high variance in detail area, low variance in smooth and edge areas. Also comparing the variance of the enhanced image by both LHE and global area histogram equalization (GHE) methods shows that one from LHE outperforms. In addition, the enlarged image from small area is shown clearly by visualization. All results compare with the conventional methods such as fuzzy c-means (FCM).
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Enhancement of color image obtained from PCA-FCM technique using local area histogram equalization
(2002-12-01)
Chitwong, S.
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Boonmee, T.
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Cheevasuvit, F.
This paper presents local area enhancement of the segmented color image obtained from the multi-spectral image clustering by using FCM (fuzzy c-means). In case, the multi-spectral images, which have the number of bands more than that of 3, must decrease the data volume to remain the number of bands of 3 in order to correspond with the meaning of red, green, and blue images. PCA (Principal Components Analysis) is then used to transform original multi-spectral images into PCA images. The first three components having information more than that of original images of 95% is assigned as red, green, and blue images, namely RGB color image. FCM clustering apply to RGB color image, separately. This method is called the PCA-FCM technique being the multi-spectral image clustering. By applying such technique, the result images consisted of red, green, and blue images separately are the segmented images. By histogram equalization algorithm, the result of local area enhancement based on a number of clusters as the segmented image can solve effect of intensity saturation from global area enhancement and the perceptibility of color image is clearly improved.
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Fusion of principal component of multispectral bands with PAN band using HIS and wavelet transform
(2002-01-01)
Chitwong, S.
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Cheevasuvit, F.
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Homthong, J.
Since RGB images derived from multispectral (TM) images will lose some information, in this paper we present the method to solve such problem by using principal component analysis (PCA) which transforms TM images into the principal component images (PCs), while the high resolution PAN data is decomposed by wavelet transform. Thus, RGB images are assigned by the first three principal component images which normally have approximately 95% of the information in the original images. The intensity image from RGB to HIS transformation is replaced by the lower frequency coefficient of wavelet transform of PAN data corresponding to multispectral images. HIS to RGB transformation is then applied. The fused RGB image using our method can obtain more details.
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Specified harmonic removal of digital comb filter by root moments
(2002-01-01)
Thangsomvorapong, P.
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Cheevasuvit, F.
This paper presents the designing of comb filter coefficients removing some undesired harmonic frequencies. The root moment method has been used to generate the desired comb filter coefficients. The proposed method is quite suitable when the relation of 2n and fundamental to is fractional.
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TMS 320C31-based narrow-band noise rejection Kalman filter implementation
(2002-01-01)
Dejhan, K.
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Yimmun, S.
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Trirat, A.
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Cheevasuvit, F.
This paper proposes a design and development of narrow frequency band filter based on Kalman algorithm by using TMS 320C31 as processor. The center frequency of this filter is between 10 Hz to 1.5 kHz by changing the coefficient of sinusoidal model in normal form realization and the results have been carried out. It is used to reject the narrow-band noises.
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Automatic indexing system for atmospheric laser radar data
(2002-01-01)
Lerkvaranyu, S.
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Miyanaga, Y.
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Dejhan, K.
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Cheevasuvit, F.
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Mizutani, K.
The purpose of this paper is to design a new method for an automatic indexing system with unsupervised conditions. In this paper, the method of a self-organizing clustering network is adopted. It is used to classify and index a large amount of real atmospheric laser radar data. Initially, the parameters of each cluster will start with random initial values and are adapted with the algorithm. In this paper, six groups are clustered from the given data. It is also shown that some of these indicate quite important atmospheric condition characteristics.

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