Input Color Research Articles

Studies on Phenolic Content and Polyphenol Oxidase Activity of Sugarcane Varieties with Reference to Sugar Processing

The phenolic content of sugarcane varieties was analysed during 6, 10 and 12 months age. The total phenolic content (TPC) was found to increase from 10 to 20 mg/100 ml (6 months) to 70–90 mg/100 ml (12 months) and stabilize during peak maturity period. Concentration of phenolics was found to be higher at the top portion of the sugarcane. The raw juice from cane samples were clarified by defecation and 30–40 % removal of TPC was observed. The sugar samples and the intermediate process products collected from sugar factories were analysed for the phenolic content and colour. Dark coloured sugars and intermediate products were found to have higher phenolics. Enzymic browning due to polyphenol oxidase (PPO) activity contributes significantly to colouring of cane juice. The absorbance increased to an extent of 70–80 % during the first 10 min of juice extraction. Colour input to sugar process can be reduced by inhibition of PPO activity of cane juice by chemical inhibitors and heating. Ascorbic acid alone inhibited PPO activity by 35 % and to an extent of 85 % combined with heating. Juice holding time in mills for 10–15 min increases enzymic browning hence; heating the juice instantly on extraction could reduce the colour formation to an extent of 40 %.

Two variants of the sign subband adaptive filter with improved convergence rate

Sign algorithms (SAs) have attracted much attention because of their robustness against impulsive interference. To reduce the computational cost of SAs, a sign subband adaptive filter (SSAF) has recently been proposed. However, the SSAF converges slowly and the convergence rate of the SSAF does not increase with the number of subbands. In this paper, two variants of the SSAF, called the affine projection SSAF (AP-SSAF) and the proportionate SSAF (P-SSAF), are proposed to solve this problem. The AP-SSAF updates the tap-weight vector based on several previous input vectors, which can not only maintain robustness against impulsive interference, but also increase the convergence rate for both white and colored input signals; the P-SSAF incorporates a gain distribution matrix into the SSAF to proportionately adapt the tap-weight vector of the adaptive filter, which can both maintain robustness against impulsive interference and increase the convergence rate of the SSAF for sparse system identification. Simulation results are presented to demonstrate the improved performance of the AP-SSAF and the P-SSAF.

Nanohole-array-based device for 2D snapshot multispectral imaging

We present a two-dimensional (2D) snapshot multispectral imager that utilizes the optical transmission characteristics of nanohole arrays (NHAs) in a gold film to resolve a mixture of input colors into multiple spectral bands. The multispectral device consists of blocks of NHAs, wherein each NHA has a unique periodicity that results in transmission resonances and minima in the visible and near-infrared regions. The multispectral device was illuminated over a wide spectral range, and the transmission was spectrally unmixed using a least-squares estimation algorithm. A NHA-based multispectral imaging system was built and tested in both reflection and transmission modes. The NHA-based multispectral imager was capable of extracting 2D multispectral images representative of four independent bands within the spectral range of 662 nm to 832 nm for a variety of targets. The multispectral device can potentially be integrated into a variety of imaging sensor systems.

Information authentication system using interference of two beams in gyrator transform domain

A novel information authentication system, i.e., an asymmetric optical interference of two beams in the gyrator transform (GT) domain, is proposed. In this algorithm, the input color image is divided into R, G, and B channels. The complex field of each channel is constructed by the inverse Fourier transform of the channel attached with a random phase function. The phase-only mask (POM) and amplitude-only mask (AOM) are analytically derived from the complex field. The POM and AOM are separately gyrator transformed. The two asymmetric phase keys and two encrypted images are obtained by the amplitude truncations and phase truncations of the transform images, respectively. Finally, the encoded image is produced by the interference of two encrypted images. The two asymmetric keys and two angle parameters of the GT are regarded as additional keys for each channel to enhance the security level of the cryptosystem. The noniterative authentication procedure is devoid of any silhouette problem. The proposed system can be implemented digitally or optically, and its architecture is free from optical misalignment problems. The theoretical analysis and numerical simulation results both validate the proposed technique.

Background Subtraction Based on Color and Depth Using Active Sensors

Depth information has been used in computer vision for a wide variety of tasks. Since active range sensors are currently available at low cost, high-quality depth maps can be used as relevant input for many applications. Background subtraction and video segmentation algorithms can be improved by fusing depth and color inputs, which are complementary and allow one to solve many classic color segmentation issues. In this paper, we describe one fusion method to combine color and depth based on an advanced color-based algorithm. This technique has been evaluated by means of a complete dataset recorded with Microsoft Kinect, which enables comparison with the original method. The proposed method outperforms the others in almost every test, showing more robustness to illumination changes, shadows, reflections and camouflage.

Joint Depth Map and Color Consistency Estimation for Stereo Images with Different Illuminations and Cameras

Abstract—In this paper, we propose a method that infers both accurate depth maps and color-consistent stereo images for radiometrically varying stereo images. In general, stereo matching and performing color consistency between stereo images are a chicken-and-egg problem since it is not a trivial task to simultaneously achieve both goals. Hence, we have developed an iterative framework in which these two processes can boost each other. First, we transform the input color images to log-chromaticity color space, from which a linear relationship can be established during constructing a joint pdf of transformed left and right color images. From this joint pdf, we can estimate a linear function that relates the corresponding pixels in stereo images. Based on this linear property, we present a new stereo matching cost by combining Mutual Information (MI), SIFT descriptor, and segment-based plane-fitting to robustly find correspondence for stereo image pairs which undergo radiometric variations. Meanwhile, we devise a Stereo Color Histogram Equalization (SCHE) method to produce color-consistent stereo image pairs, which conversely boost the disparity map estimation. Experimental results show that our method produces both accurate depth maps and color-consistent stereo images, even for stereo images with severe radiometric differences.

Variable Step Size LMS Algorithm Based on Function Control

This paper proposes a function-controlled variable step size least mean square (VSLMS) algorithm for channel estimation in low-SNR or colored input signals. The proposed method aligns the step size update with the steady-state error and alleviates the impact of high-level noise. It improves the filter performance in terms of fast convergence rate and low misadjustment error. Simulation results demonstrate the effectiveness and verify the theoretic analysis of the proposed VSLMS algorithm.

Steady-state mean-square error analysis of regularized normalized subband adaptive filters

The normalized subband adaptive filter (NSAF) has faster convergence rate than the normalized least-mean-square (NLMS) algorithm for colored input signals. Regularization of the NSAF is of importance in practical applications. In this paper, we analyze the steady-state mean-square error (MSE) of regularized NSAFs. The analysis is carried out based on the derivation of a variable regularization matrix NSAF (VRM-NSAF). Theoretical expressions for the steady-state MSE of two regularized NSAFs are derived under some assumptions. Simulation results are given to support the theoretical analysis.

A Robust Face Detection Method Based on Skin Color and Edges

In this paper we propose a method to detect human faces in color images. Many existing systems use a window-based classifier that scans the entire image for the presence of the human face and such systems suffers from scale variation, pose variation, illumination changes, etc. Here, we propose a lighting insensitive face detection method based upon the edge and skin tone information of the input color image. First, image enhancement is performed, especially if the image is acquired from an unconstrained illumination condition. Next, skin segmentation in YCbCr and RGB space is conducted. The result of skin segmentation is refined using the skin tone percentage index method. The edges of the input image are combined with the skin tone image to separate all non- face regions from candidate faces. Candidate verification using primitive shape features of the face is applied to decide which of the candidate regions corresponds to a face. The advantage of the proposed method is that it can detect faces that are of different sizes, in different poses, and that are making different expressions under unconstrained illumination conditions

Variational Exemplar-Based Image Colorization

In this paper, we address the problem of recovering a color image from a grayscale one. The input color data comes from a source image considered as a reference image. Reconstructing the missing color of a grayscale pixel is here viewed as the problem of automatically selecting the best color among a set of color candidates while simultaneously ensuring the local spatial coherency of the reconstructed color information. To solve this problem, we propose a variational approach where a specific energy is designed to model the color selection and the spatial constraint problems simultaneously. The contributions of this paper are twofold. First, we introduce a variational formulation modeling the color selection problem under spatial constraints and propose a minimization scheme, which computes a local minima of the defined nonconvex energy. Second, we combine different patch-based features and distances in order to construct a consistent set of possible color candidates. This set is used as input data and our energy minimization automatically selectsthe best color to transfer for each pixel of the grayscale image. Finally, the experiments illustrate the potentiality of our simple methodology and show that our results are very competitive with respect to the state-of-the-art methods.

최대색차신호 표를 이용한 컬러 채도 향상

본 논문에서는 디지털 영상의 색상을 유지하면서 영상의 명암대비 향상과 함께 채도를 향상시키는 방법을 제시한다. 제안방법은 명암대비 향상 후 밝기 변화에 따른 시각적인 채도 변화를 보정하기 위해 최대색차신호 테이블을 이용한다. 최대색차신호 테이블로부터 휘도변화에 따른 가중치를 구하고, 입력 색차신호에 가중치를 곱하여 채도를 밝기에 적응적으로 보정한다. 또한 사용자가 입력한 만큼의 채도를 향상시키는 과정에서 과도한 채도 향상으로 인한 왜곡을 막기 위해 휘도와 색상에 따른 채도의 상관관계를 고려하여 색차신호가 올바른 색역에 사상될 수 있도록 한다. 다양한 특성을 갖는 영상에 대한 실험을 통해 제안방법은 기존방식과 비교하여 효과적으로 컬러 영상의 선명도를 향상시킴을 확인하였다. In this paper, we propose a new color image enhancement method to improve the color saturation as well as luminance contrast in the YCbCr color space. The proposed method uses the maximum color difference table to compensate the perceived saturation changes due to luminance contrast changes. To improve the color saturation, the method first calculates the weighting factor by using the maximum color difference table and then multiplies the weighting factor to the input color difference signals. In this step, it maps color difference signals to proper color region to prevent the color distortion by considering the correlation of color saturations depending on the luminance and hue. The experimental results show that our method effectively improves color saturation compared to the conventional methods.

Color Removal Considering Differences of Colors and Achromatic Color Preservation

In this letter, a novel color removal method considering differences of colors in an input color image and achromatic color preservation is proposed. The achromatic color preservation is assigning lightness values to gray-levels concerning achromatic pixels for natural impression. The effectiveness and validity of the proposed method are verified by experiments.

CMEIAS Quadrat Maker: A Digital Software Tool to Optimize Grid Dimensions and Produce Quadrat Images for Landscape Ecology Spatial Analysis

This paper describes CMEIAS Quadrat Maker, a new digital computing tool designed to alleviate the nontrivial problem of optimizing the grid-lattice dimensions and automating the production of size-optimized quadrat images for plot-based spatial pattern analysis in landscape ecology. The program is written for 32-bit and 64-bit Window’s operating systems and handles both 8-bit grayscale and 24-bit color input images. Following a brief user interaction, the software application transforms a copy of the input landscape image into an annotated, color index image with optimized grid overlay and column-row labeling of individual quadrats, cuts a copy of the landscape image into quadrats defined by the optimized grid raster, and then saves each individual quadrat image with a file name indicating its unique location within the landscape domain, now ready for stack building and automated image analysis. Version 1.0 of this computing technology is implemented into a software package containing the executable file, user manual and tutorial images that will be freely available at http://cme.msu.edu/cmeias/. This new computing technology will facilitate quadrat-based analyses of how spatial patterns vary with the scale at which they are measured, and will also strengthen microscopy-based approaches for understanding the spatial ecology of microbial biofilm communities.

Influence Analysis of Color Input Target to the Scanner Color Characteristic

Scanner is the indispensable image acquisition equipment in the prepress system, high quality ICC profile is significant to reflect the color expression of scanner, and the character of ICC profile is influenced in a great extent by the color input target. The subject is to set up the ICC profile by scanning and data processing Kodak IT8.7/2, Goldencolor GCT 3.0 and GretagMacbeth ColorChecker SG, get the influence of each color input target to the scanner color characteristic through the accuracy analysis and color gamut comparison. Research shows that three kinds of color target has its own advantage, Kodak IT8.7/2 has big color gamut, high accuracy, and better reappearance ability, meets the needs of the everyday users; GretagMacbeth ColorChecker SG is good to the reappearance of high saturate manuscript, and its precision is high, applying to recreate natural landscape; Glodencolor GCT 3.0 is of high precision and larger color gamut, but its expression ability is not good enough in the section of high saturation red and magenta, it can produce high quality scanner ICC profile also. Consequently, it should be taken into consideration of the manuscript, color gamut, accuracy and cost-effective factors comprehensively when choosing scanner color target, eventually you get a satisfactory scanning result.

Scheduled-Step-Size Affine Projection Algorithm

An approach for scheduling the step sizes of an adaptive filter using the affine projection algorithm (APA) is proposed so that its mean-square deviation (MSD) learning curve can be guided along a pre-designed trajectory. This approach eliminates the parameter-tuning process and does not require estimating unmeasurable stochastic quantities. Furthermore, a step-size lower bound is derived in random-walk-modeled environments that leads the adaptive filter to achieve the smallest steady-state MSD, while in stationary environments, the closer to zero the step size is, the smaller the steady-state MSD. For efficient memory usage in practice, the schedule is modified from full-table step sizes to a few down-sampled step sizes without performance degradation. In a simulation, the scheduled-step-size APA exhibits fast convergence and produces small steady-state error not only for a white signal but also for various colored input signals for a properly chosen projection order. The proposed algorithm also demonstrates greater robustness over different signal-to-noise ratios than the existing variable-step-size APAs.

A novel adaptive color to grayscale conversion algorithm for digital images

A color image sent to the monochrome device must undergo the color-to-grayscale conversion process. Although the conventional color-to-grayscale conversion algorithms are widely used, their performance is questionable in certain circumstances and poor quality resultant grayscale images will be produced. This paper tackled some drawbacks of the conventional methods by introducing a novel approach namely the Adaptive Color to Grayscale (ACGS) conversion algorithm. In the proposed ACGS method, the pixels distribution analysis of input color images was performed to calculate the weight contribution of red, green, and blue components during the conversion process. The extensive experimental results demonstrated the superior qualitative and quantitative performance of the proposed ACGS method over the conventional algorithms and its feasibility in real-time video processing applications. These promising results suggest that the proposed ACGS method is suitable to be employed in the monochrome devices for pre- and post- processing of digital images. Key words: Color-to-grayscale conversion, adaptive, color image, grayscale image, image pre-processing.

3D Surface Reconstruction from Single 2D Image

The image-based 3D reconstruction technique is an important method of 3D data passive acquired in computer vision. Aimed at the limitation of traditional SFS based 3D surface reconstruction method, a combined image-based 3D surface reconstruction method is given in this paper. Firstly, the pretreatment method of gradation is applied to convert the input color image to 256 gray image; secondly, shape from shading method is applied to recover the 3D profile of object; finally, the B-spline technique is adopted to reconstruct the model of surface and improve the resolution of surface. The key techniques such as the principle and algorithm of B-spline interpolation reconstruction are analyzed, and the experimental results are also given. The single-image based 3D reconstruction method given in this paper will supply a helpful condition for the extensive used of SFS technique.

An orthogonal polynomials transform-based variable block size adaptive vector quantisation for colour image coding

In this paper, a new adaptive vector quantisation with variable block size based on orthogonal polynomials is proposed for colour image coding. The input colour image is partitioned into fixed larger block sizes and the homogeneity/complexity of the local region is tested with the mean-normalised variance classifier. The homogeneous regions are encoded with fixed larger blocks and the complex regions are further divided into smaller block sizes for encoding as it gives the wealth of low-level information such as the high detail and high number of contrast edges. The integer-based orthogonal polynomials transform is then applied on the variable block sizes utilising the inter-correlation property of individual colour planes and interactions among the colour planes so as to reduce the vector dimension and hence the less computational cost. The proposed technique generates two dynamic codebooks and two backup codebooks adaptively and use rate-distortion cost criteria to encode both the homogeneous and complex regions separately. Since the proposed method encodes all the three colour components in single pass, the colour image encoding time is slightly higher than that of grey scale image coding but in contrast to three times in the existing colour image coding techniques.

Novel Shoulder-Surfing Resistant Authentication Schemes using Text-Graphical Passwords

There are many applications which require the user to be authenticated before being permitted to perform certain tasks. Text password-based authentication is a popularly used authentication mechanism. Despite having greater security, text-passwords are characterized by selection of a weak and easy to remember passwords. Users also tend to write them down and share them with friends, family members and colleagues defeating the security provided by text-passwords. Graphical passwords offer an alternative to text passwords as the password space is typically higher, less prone to dictionary attacks and easier to remember visually. However, they suffer from shoulder-surfing attacks. In this paper, we propose two authentication schemes that support keyboard as well as graphical mouse-based input that map password characters to other regions of the password space. This shields the user’s password from being known to the adversary thus deflecting shoulder-surfing and spyware attacks. The schemes include both single and multi color input images consisting of printable characters. An analysis of security, usability, memorability and social engineering aspects of the proposed schemes is presented. Future research directions are also presented

Integer Wavelet based Secret Data Hiding by Selecting Variable Bit Length

is a process of hiding secret informations like image, video, audio, and text message in a carriers like image, video, and audio. Proposed method uses the secret information as a text message which is embedded in a color image. The existing methods hide the information using constant bit length in integer wavelet coefficients. This paper uses variable bit length based on integer wavelet coefficients to hide the data in a particular positions using secret key by LSB substitution method. Hence this algorithm increases the embedding capacity of the text message and obtained stego image is imperceptible for human vision. This technique embeds binary bit stream of secret text message into the 8 bit color image. The embedded confidential information can be extracted from stego image without the knowledge of original image by considering the same secret key. On average of 2.50 bits can be embedded in each wavelet coefficient of the input color image. Hence this method gives better results in both embedding capacity and PSNR than the existing methods.