An essential tool for fast image processing is the computation of image features. Integral Images... more An essential tool for fast image processing is the computation of image features. Integral Images are a popular approach to obtain this goal. A drawback of this technique is that it only allows for rectangular image features. In this paper, the goal is to investigate if circular image features outperform rectangular image features using integral image approach. Additionally, experimental work for the purpose of comparison between different and new descriptor methods has also been presented in this paper.
2008 IEEE International Multitopic Conference, 2008
Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assiste... more Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assisted enhancement of exudates in fundus images of human retina for the diagnosis of diabetic retinopathy. Diabetic retinopathy is a common disease in diabetic persons. ...
Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assiste... more Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assisted enhancement of exudates in fundus images of human retina for the diagnosis of diabetic retinopathy. Diabetic retinopathy is a common disease in diabetic persons. ...
Proceedings of the 12th ACM SIGGRAPH International Conference on Virtual-Reality Continuum and Its Applications in Industry - VRCAI '13, 2013
The affordance of independent learning is one of the most important advantages of computer simula... more The affordance of independent learning is one of the most important advantages of computer simulators for surgical training. This advantage can get dull if the simulator does not provide the useful instructional feedback to the user and the instructor has to supervise and tutor the trainee while using the simulator. In fact the continued need of instructor feedback with most existing simulators is often cited as a primary reason for the reluctance of many medical schools to fully embrace simulator technology [Sewell 2007]. Thus the incorporation of relevant, intuitive metrics in a way that it provides a constructive feedback which facilitates independent learning is essential for the development of efficient simulators. Evaluating a trainee surgeon's performance as per trainer surgeon's desire is always a challenging problem in the development of minimal invasive surgery simulators. In this research we have proposed a novel metric for trainee surgeons' performance evaluation using machine learning algorithms.
2013 IEEE International Conference of IEEE Region 10 (TENCON 2013), 2013
Surgical simulation is very important field in medical studies. It provides a platform to the sur... more Surgical simulation is very important field in medical studies. It provides a platform to the surgeons for practicing laparoscopic surgery. While practicing surgery in virtual reality simulators, surgeons do not really know if the organs depict realistic behavior or not. Elastic properties of soft tissues show realistic behavior of organs in simulators. In this paper, mechanical properties for soft tissues have been derived from CT scan images on the basis of their hounsfield number for surgical simulations so that organs can depict realistic behavior in simulation. These properties are then embedded to the surface model for generation of accurate mathematical model.
Surgical simulations are becoming the defacto standard for training surgeons for Minimally Invasi... more Surgical simulations are becoming the defacto standard for training surgeons for Minimally Invasive Surgery (MIS). Input devices determine how a user will experience the functionality of a simulator. Therefore it is very important to determine which input devices are suitable for the kind of operation that is being performed in a simulator. It is important to perform a user study of these input devices in order to determine their effects on the performance of the software and its usability. In this research we perform a usability study on the different input devices available and study the effect of these input devices on the learning curve of a commercial simulator. We perform our experiments using a mouse, a joystick without force feedback, joystick with force feedback, the PHANTOM Omni device and a custom device designed by our research lab. Using these devices we perform several exercises and study the effect of using these input controls on the learnability of a popular commercial simulator used for training surgeons.
Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon hybrid trans... more Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon hybrid transform features is presented. We first ana-lyzed two different transform domains (Discrete Cosine Transform and Discrete Contourlet Transform) separately, to extract features for ...
Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon joint transf... more Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon joint transform features is presented. We first analyzed two different transform domains (Discrete Cosine Transform and Dis-crete Wavelet Transform) separately, to extract features for ...
2012 International Conference on Digital Image Computing Techniques and Applications (DICTA), 2012
Automatic recognition of suspects from forensic sketches is of considerable interest to the law e... more Automatic recognition of suspects from forensic sketches is of considerable interest to the law enforcement agencies. However, this task is complex due to the heterogenous nature of face sketches and photographs. To address this challenge, previous approaches generally learn a transformation of a sketch to photo or a photo to sketch at the image or feature level in order to reduce the modality gap. Such a transformation may be indeterministic and if learned from training data, is likely to over-fit the sketch artist's drawing technique. Instead, we formulate the problem in the context of matching local self similarities which are independently computed from a face sketch and a photo. The proposed Facial Self Similarity (FSS) descriptor is obtained by correlation of a small face patch with its local neighborhood. Thus, our approach avoids the need of a modality transformation, while implicitly reducing the intermodality gap. The proposed FSS descriptor is evaluated on the CUHK Face Sketch database using sketch-photo pairs of 311 subjects. The FSS descriptor demonstrates high recognition accuracy of 99.53% and outperforms current techniques. We also evaluate the robustness of the descriptor to anomalies such as matching sketches to blurred photographs.
2008 2nd International Conference on Advances in Space Technologies, 2008
This paper proposes an approach for structure based separation of image objects using fuzzy morph... more This paper proposes an approach for structure based separation of image objects using fuzzy morphology for aerial images. With set operators in fuzzy context, we apply an adaptive alpha-cut morphological processing for edge detection and image enhancement. A Top-hat transform is first applied to the input image and the resulting image is thresholded to a binary form. The image is then thinned using hit-or-miss transform. Finally, m-connectivity is used to keep the desired number of connected pixels. The output image is overlaid on the original for enhanced boundaries. Experiments were performed on a variety of aerial images. A comparison to other edge enhancement techniques like and filtering shows improved performance by the proposed technique.
2013 12th International Conference on Document Analysis and Recognition, 2013
ABSTRACT Ink mismatch detection provides important clues to forensic document examiners by identi... more ABSTRACT Ink mismatch detection provides important clues to forensic document examiners by identifying whether a particular handwritten note was written with a specific pen, or to show that some part (e.g. signature) of a note is written with a different ink as compared to the rest of the note. In this paper, we show that a hyper spectral image (HSI) of handwritten notes can discriminate between inks that are visually similar in appearance. For this purpose, we develop the first ever hyper spectral image database of handwritten notes in various blue and black inks, comprising a total of 70 hyper spectral images each in 33 bands of the visible spectrum. In an unsupervised clustering scheme, the spectral responses of inks fall into separate clusters to allow segmentation of two different inks in a questioned document. The same method fails to segment inks correctly when applied to RGB scans of these documents, since the inks are very hard to distinguish in the visible spectral range. HSI overcomes the shortcomings of RGB and allows better discrimination between inks. We further evaluate which subset of bands from HSI is most useful for the purpose of ink mismatch detection. We hope that these findings will stimulate the use of HSI in document analysis research, especially for questioned document examination.
We propose `Contour Code', a novel representation and binary hash table encoding for multispectra... more We propose `Contour Code', a novel representation and binary hash table encoding for multispectral palmprint recognition. We first present a reliable technique for the extraction of a region of interest (ROI) from palm images acquired with non-contact sensors. The Contour Code representation is then derived from the Nonsubsampled Contourlet Transform. A uniscale pyramidal filter is convolved with the ROI followed by the application of a directional filter bank. The dominant directional subband establishes the orientation at each pixel and the index corresponding to this subband is encoded in the Contour Code representation. Unlike existing representations which extract orientation features directly from the palm images, the Contour Code uses a two stage filtering to extract robust orientation features. The Contour Code is binarized into an efficient hash table structure that only requires indexing and summation operations for simultaneous one-to-many matching with an embedded score level fusion of multiple bands. We quantitatively evaluate the accuracy of the ROI extraction by comparison with a manually produced ground truth. Multispectral palmprint verification results on the PolyU and CASIA databases show that the Contour Code achieves an EER reduction upto 50%, compared to state-of-the-art methods.
This paper presents an evaluation of wavelet filters performance for the task of steganalysis. We... more This paper presents an evaluation of wavelet filters performance for the task of steganalysis. We analyzed six different wavelet filters namely Daubachies, Coiflets, Symlets, Discrete Meyer, Biorthogonal and Reverse Biorthogonal families for feature extraction in a wavelet based steganalysis technique. Two publicly available steganography tools, namely the F5 steganography and the Model Based steganography were used to embed messages in a database of clean images to develop steganographic database of images. A Fisher Linear Discriminant classifier is trained using all six feature sets extracted from both clean and steganographic images separateley and subsequently used for classification. Experiments revealed that the features using the 'haar' (db1) wavelet filter gave the best steganalysis performance.
Pacific-Rim Symposium on Image and Video Technology, 2009
In this paper, a universal steganalysis scheme for JPEG images based upon joint transform feature... more In this paper, a universal steganalysis scheme for JPEG images based upon joint transform features is presented. We first analyzed two different transform domains (Discrete Cosine Transform and Discrete Wavelet Transform) separately, to extract features for steganalysis. Then a combination of these two feature sets is constructed and employed for steganalysis. A Fisher Linear Discriminant classifier is trained on features from both clean and steganographic images using all three feature sets and subsequently used for classification. Experiments performed on images embedded with two variants of F5 and Model based steganographic techniques reveal the effectiveness of proposed steganalysis approach by demonstrating improved detection for joint features.
In this paper, a universal steganalysis scheme for JPEG images based upon hybrid transform featur... more In this paper, a universal steganalysis scheme for JPEG images based upon hybrid transform features is presented. We first analyzed two different transform domains (Discrete Cosine Transform and Discrete Contourlet Transform) separately, to extract features for steganalysis. Then a combination of these two feature sets is constructed and employed for steganalysis. A Fisher Linear Discriminant classifier is trained on features from both clean and steganographic images using all three feature sets and subsequently used for classification. Experiments performed on images embedded with two variants of F5 and Model based steganographic techniques reveal the effectiveness of proposed steganalysis approach by demonstrating improved detection for hybrid features.
International Conference on Advances in Space Technologies, 2008
This paper proposes an approach for structure based separation of image objects using fuzzy morph... more This paper proposes an approach for structure based separation of image objects using fuzzy morphology for aerial images. With set operators in fuzzy context, we apply an adaptive alpha-cut morphological processing for edge detection and image enhancement. A Top-hat transform is first applied to the input image and the resulting image is thresholded to a binary form. The image is then thinned using hit-or-miss transform. Finally, m-connectivity is used to keep the desired number of connected pixels. The output image is overlaid on the original for enhanced boundaries. Experiments were performed on a variety of aerial images. A comparison to other edge enhancement techniques like and filtering shows improved performance by the proposed technique.
An essential tool for fast image processing is the computation of image features. Integral Images... more An essential tool for fast image processing is the computation of image features. Integral Images are a popular approach to obtain this goal. A drawback of this technique is that it only allows for rectangular image features. In this paper, the goal is to investigate if circular image features outperform rectangular image features using integral image approach. Additionally, experimental work for the purpose of comparison between different and new descriptor methods has also been presented in this paper.
2008 IEEE International Multitopic Conference, 2008
Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assiste... more Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assisted enhancement of exudates in fundus images of human retina for the diagnosis of diabetic retinopathy. Diabetic retinopathy is a common disease in diabetic persons. ...
Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assiste... more Abstract-This paper presents a novel algorithm based on Fuzzy Morphology for the computer-assisted enhancement of exudates in fundus images of human retina for the diagnosis of diabetic retinopathy. Diabetic retinopathy is a common disease in diabetic persons. ...
Proceedings of the 12th ACM SIGGRAPH International Conference on Virtual-Reality Continuum and Its Applications in Industry - VRCAI '13, 2013
The affordance of independent learning is one of the most important advantages of computer simula... more The affordance of independent learning is one of the most important advantages of computer simulators for surgical training. This advantage can get dull if the simulator does not provide the useful instructional feedback to the user and the instructor has to supervise and tutor the trainee while using the simulator. In fact the continued need of instructor feedback with most existing simulators is often cited as a primary reason for the reluctance of many medical schools to fully embrace simulator technology [Sewell 2007]. Thus the incorporation of relevant, intuitive metrics in a way that it provides a constructive feedback which facilitates independent learning is essential for the development of efficient simulators. Evaluating a trainee surgeon's performance as per trainer surgeon's desire is always a challenging problem in the development of minimal invasive surgery simulators. In this research we have proposed a novel metric for trainee surgeons' performance evaluation using machine learning algorithms.
2013 IEEE International Conference of IEEE Region 10 (TENCON 2013), 2013
Surgical simulation is very important field in medical studies. It provides a platform to the sur... more Surgical simulation is very important field in medical studies. It provides a platform to the surgeons for practicing laparoscopic surgery. While practicing surgery in virtual reality simulators, surgeons do not really know if the organs depict realistic behavior or not. Elastic properties of soft tissues show realistic behavior of organs in simulators. In this paper, mechanical properties for soft tissues have been derived from CT scan images on the basis of their hounsfield number for surgical simulations so that organs can depict realistic behavior in simulation. These properties are then embedded to the surface model for generation of accurate mathematical model.
Surgical simulations are becoming the defacto standard for training surgeons for Minimally Invasi... more Surgical simulations are becoming the defacto standard for training surgeons for Minimally Invasive Surgery (MIS). Input devices determine how a user will experience the functionality of a simulator. Therefore it is very important to determine which input devices are suitable for the kind of operation that is being performed in a simulator. It is important to perform a user study of these input devices in order to determine their effects on the performance of the software and its usability. In this research we perform a usability study on the different input devices available and study the effect of these input devices on the learning curve of a commercial simulator. We perform our experiments using a mouse, a joystick without force feedback, joystick with force feedback, the PHANTOM Omni device and a custom device designed by our research lab. Using these devices we perform several exercises and study the effect of using these input controls on the learnability of a popular commercial simulator used for training surgeons.
Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon hybrid trans... more Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon hybrid transform features is presented. We first ana-lyzed two different transform domains (Discrete Cosine Transform and Discrete Contourlet Transform) separately, to extract features for ...
Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon joint transf... more Abstract. In this paper, a universal steganalysis scheme for JPEG im-ages based upon joint transform features is presented. We first analyzed two different transform domains (Discrete Cosine Transform and Dis-crete Wavelet Transform) separately, to extract features for ...
2012 International Conference on Digital Image Computing Techniques and Applications (DICTA), 2012
Automatic recognition of suspects from forensic sketches is of considerable interest to the law e... more Automatic recognition of suspects from forensic sketches is of considerable interest to the law enforcement agencies. However, this task is complex due to the heterogenous nature of face sketches and photographs. To address this challenge, previous approaches generally learn a transformation of a sketch to photo or a photo to sketch at the image or feature level in order to reduce the modality gap. Such a transformation may be indeterministic and if learned from training data, is likely to over-fit the sketch artist's drawing technique. Instead, we formulate the problem in the context of matching local self similarities which are independently computed from a face sketch and a photo. The proposed Facial Self Similarity (FSS) descriptor is obtained by correlation of a small face patch with its local neighborhood. Thus, our approach avoids the need of a modality transformation, while implicitly reducing the intermodality gap. The proposed FSS descriptor is evaluated on the CUHK Face Sketch database using sketch-photo pairs of 311 subjects. The FSS descriptor demonstrates high recognition accuracy of 99.53% and outperforms current techniques. We also evaluate the robustness of the descriptor to anomalies such as matching sketches to blurred photographs.
2008 2nd International Conference on Advances in Space Technologies, 2008
This paper proposes an approach for structure based separation of image objects using fuzzy morph... more This paper proposes an approach for structure based separation of image objects using fuzzy morphology for aerial images. With set operators in fuzzy context, we apply an adaptive alpha-cut morphological processing for edge detection and image enhancement. A Top-hat transform is first applied to the input image and the resulting image is thresholded to a binary form. The image is then thinned using hit-or-miss transform. Finally, m-connectivity is used to keep the desired number of connected pixels. The output image is overlaid on the original for enhanced boundaries. Experiments were performed on a variety of aerial images. A comparison to other edge enhancement techniques like and filtering shows improved performance by the proposed technique.
2013 12th International Conference on Document Analysis and Recognition, 2013
ABSTRACT Ink mismatch detection provides important clues to forensic document examiners by identi... more ABSTRACT Ink mismatch detection provides important clues to forensic document examiners by identifying whether a particular handwritten note was written with a specific pen, or to show that some part (e.g. signature) of a note is written with a different ink as compared to the rest of the note. In this paper, we show that a hyper spectral image (HSI) of handwritten notes can discriminate between inks that are visually similar in appearance. For this purpose, we develop the first ever hyper spectral image database of handwritten notes in various blue and black inks, comprising a total of 70 hyper spectral images each in 33 bands of the visible spectrum. In an unsupervised clustering scheme, the spectral responses of inks fall into separate clusters to allow segmentation of two different inks in a questioned document. The same method fails to segment inks correctly when applied to RGB scans of these documents, since the inks are very hard to distinguish in the visible spectral range. HSI overcomes the shortcomings of RGB and allows better discrimination between inks. We further evaluate which subset of bands from HSI is most useful for the purpose of ink mismatch detection. We hope that these findings will stimulate the use of HSI in document analysis research, especially for questioned document examination.
We propose `Contour Code', a novel representation and binary hash table encoding for multispectra... more We propose `Contour Code', a novel representation and binary hash table encoding for multispectral palmprint recognition. We first present a reliable technique for the extraction of a region of interest (ROI) from palm images acquired with non-contact sensors. The Contour Code representation is then derived from the Nonsubsampled Contourlet Transform. A uniscale pyramidal filter is convolved with the ROI followed by the application of a directional filter bank. The dominant directional subband establishes the orientation at each pixel and the index corresponding to this subband is encoded in the Contour Code representation. Unlike existing representations which extract orientation features directly from the palm images, the Contour Code uses a two stage filtering to extract robust orientation features. The Contour Code is binarized into an efficient hash table structure that only requires indexing and summation operations for simultaneous one-to-many matching with an embedded score level fusion of multiple bands. We quantitatively evaluate the accuracy of the ROI extraction by comparison with a manually produced ground truth. Multispectral palmprint verification results on the PolyU and CASIA databases show that the Contour Code achieves an EER reduction upto 50%, compared to state-of-the-art methods.
This paper presents an evaluation of wavelet filters performance for the task of steganalysis. We... more This paper presents an evaluation of wavelet filters performance for the task of steganalysis. We analyzed six different wavelet filters namely Daubachies, Coiflets, Symlets, Discrete Meyer, Biorthogonal and Reverse Biorthogonal families for feature extraction in a wavelet based steganalysis technique. Two publicly available steganography tools, namely the F5 steganography and the Model Based steganography were used to embed messages in a database of clean images to develop steganographic database of images. A Fisher Linear Discriminant classifier is trained using all six feature sets extracted from both clean and steganographic images separateley and subsequently used for classification. Experiments revealed that the features using the 'haar' (db1) wavelet filter gave the best steganalysis performance.
Pacific-Rim Symposium on Image and Video Technology, 2009
In this paper, a universal steganalysis scheme for JPEG images based upon joint transform feature... more In this paper, a universal steganalysis scheme for JPEG images based upon joint transform features is presented. We first analyzed two different transform domains (Discrete Cosine Transform and Discrete Wavelet Transform) separately, to extract features for steganalysis. Then a combination of these two feature sets is constructed and employed for steganalysis. A Fisher Linear Discriminant classifier is trained on features from both clean and steganographic images using all three feature sets and subsequently used for classification. Experiments performed on images embedded with two variants of F5 and Model based steganographic techniques reveal the effectiveness of proposed steganalysis approach by demonstrating improved detection for joint features.
In this paper, a universal steganalysis scheme for JPEG images based upon hybrid transform featur... more In this paper, a universal steganalysis scheme for JPEG images based upon hybrid transform features is presented. We first analyzed two different transform domains (Discrete Cosine Transform and Discrete Contourlet Transform) separately, to extract features for steganalysis. Then a combination of these two feature sets is constructed and employed for steganalysis. A Fisher Linear Discriminant classifier is trained on features from both clean and steganographic images using all three feature sets and subsequently used for classification. Experiments performed on images embedded with two variants of F5 and Model based steganographic techniques reveal the effectiveness of proposed steganalysis approach by demonstrating improved detection for hybrid features.
International Conference on Advances in Space Technologies, 2008
This paper proposes an approach for structure based separation of image objects using fuzzy morph... more This paper proposes an approach for structure based separation of image objects using fuzzy morphology for aerial images. With set operators in fuzzy context, we apply an adaptive alpha-cut morphological processing for edge detection and image enhancement. A Top-hat transform is first applied to the input image and the resulting image is thresholded to a binary form. The image is then thinned using hit-or-miss transform. Finally, m-connectivity is used to keep the desired number of connected pixels. The output image is overlaid on the original for enhanced boundaries. Experiments were performed on a variety of aerial images. A comparison to other edge enhancement techniques like and filtering shows improved performance by the proposed technique.
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Papers by Zohaib Khan