Luminance Plane Research Articles

LED-based standard source for spectral radiance with high uniform luminance plane

LED-based standard source for spectral radiance with high uniform luminance plane

CLASSIFICATION REVIEW OF RAW SUBJECTIVE SCORES TOWARDS STATISTICAL ANALYSIS

We proposed a no reference model for quality estimation based on compression artifacts which are principal factor for determining the QoE compared to varying depth range within compression. Moreover, in our past research work, contents with strong compression have been rejected by the Subjects who graded quality of distorted videos and judged unacceptable. The results of our proposed approach conrm that our subjective scores of 120 videos are related to control of visible spatial artifacts of reconstructed videos not distorted and with consideration of User Experience (UX), It was traced out by rening raw subjective scores, it happened due to coding of spatial and temporal perceptual information according to H.264 standards mentioned by ITU only for video quality assessment, i.e., instead of coding spatial of chrominance and temporal information of luminance plane, selected test sequences were coded within luminance plane for both spatial and temporal information

Invertible Color-to-Grayscale Conversion Using Lossy Compression and High-Capacity Data Hiding

Invertible color-to-grayscale conversion is a research issue in grayscale image colorization, which is a complex problem resulting from information loss. This paper presents an innovative invertible color-to-grayscale conversion idea by independently compressing the chromaticity plane and hiding it into the corresponding luminance plane as a watermark. Since the chromaticity and luminance planes are orthogonal in the proposed method, they can be processed efficiently without mutual influence. By using an efficient lossy compression operation, we can save more chromatic information. By using two high-capacity data hiding techniques (reversible watermarking (RW) and least significant bit (LSB) substitution), we can embed the compressed chromatic information into the luminance plane perfectly. For the purpose of integrality authentication, the luminance plane is hashed as part of the embedded information before the embedding. Experimental results have shown that higher quality of reconstructed color images can be achieved by using RW, but the quality of the synthesized grayscale drops sharply. By using LSB substitution, we can obtain high-quality synthesized grayscale and reconstructed color images simultaneously. Furthermore, we have compared the proposed LSB-based scheme with several recently reported state-of-the-art methods to validate the superiority of the proposed approach.

WITHDRAWN: Image Digest using Color Vector Angle and Dominant Walsh-Hadamard Transform Coefficients

Classical image digests often investigate the luminance plane (Y) in the YCbCr color standard to produce robust hash values. However, in most cases, the images are in RGB format. So digests employing luminance planes suffered from poor discrimination. The proposed work develops a robust image digest for RGB images, which exploits all R, G, and B planes of images to obtain intense discrimination of the digest. The proposed digest reprocesses images in the database to a fixed dimension. Later, it extracts dominant approximation components by using a Gaussian Low pass filter from each color component R, G and B. Thirdly, Color Vector Angle (CVA) is applied on merged three planes of the image. Fourthly Walsh-Hadamard transform (WHT) is used on 8 × 8 blocks. The dominant dc coefficients of WHT are taken for the hash generation. Finally, it takes the Hamming distances as a similarity measurement between the original and extracted hashes. The simulation results indicate that our proposed algorithm is superior to the classification efficiency among perceptual robustness and discriminating capability.

Remote controls illusion: strange interactions across space cannot be explained by simple contrast filters

The visual system has separable visual encoding for luminance and for contrast modulation [J. Vis.8(1), B152 (2008)1534-736210.1167/8.6.1]; the two dimensions can be represented with a luminance contrast versus luminance plane. Here we use a contrast asynchrony paradigm to explore contextual effects on luminance contrast modulation: two identical rectangular bars (0.5°×2.5°) have luminance levels that modulate at 2Hz; when one bar is placed on a bright field and the other bar on a dark field, observers perceive the bars modulating in antiphase with each other and yet becoming light and dark at the same time. The antiphase perception corresponds to the change in contrast between the bars and their surrounds (a change along the contrast axis of the plane); the in-phase perception corresponds to the luminance modulation (a change along the luminance axis of the plane). We examine spatial interaction by adding bright rectangular (0.5°×2.5°) flankers on both sides of the dark-field bar and dark flankers on both sides of the bright-field bar. Remarkably, flankers produce an in-phase appearance when separated from the bars by between 2' and 4' of visual angle, and produce antiphase appearance when they directly adjoin the bars or are separated by more than 8'. To estimate the dimensions of the spatial interaction, we parametrically adjust the size of the gap between bars and flankers and the length of the flankers. We attempt to account for the results with models based on rectified difference of Gaussian filters and with rectified oriented difference of Gaussian filters. The models can account for the results when the flankers are the same height as bars, but are unable to account for the effects of increasing the flanker length. The models therefore suggest that the spatial interaction across distances requires more complex interactions of contrast filters.

Near-Infrared Coloring via a Contrast-Preserving Mapping Model.

Near-infrared gray images captured along with corresponding visible color images have recently proven useful for image restoration and classification. This paper introduces a new coloring method to add colors to near-infrared gray images based on a contrast-preserving mapping model. A naive coloring method directly adds the colors from the visible color image to the near-infrared gray image. However, this method results in an unrealistic image because of the discrepancies in the brightness and image structure between the captured near-infrared gray image and the visible color image. To solve the discrepancy problem, first, we present a new contrast-preserving mapping model to create a new near-infrared gray image with a similar appearance in the luminance plane to the visible color image, while preserving the contrast and details of the captured near-infrared gray image. Then, we develop a method to derive realistic colors that can be added to the newly created near-infrared gray image based on the proposed contrast-preserving mapping model. Experimental results show that the proposed new method not only preserves the local contrast and details of the captured near-infrared gray image, but also transfers the realistic colors from the visible color image to the newly created near-infrared gray image. It is also shown that the proposed near-infrared coloring can be used effectively for noise and haze removal, as well as local contrast enhancement.

Balancing energy use against video quality in mobile devices

It is now common to access mobile video services through various Internet-connectable devices such as game stations, smartphones and tablets. This paper proposes a new energy management scheme for mobile devices by making use of the temporal scalability available in scalable video coding (SVC) techniques. The proposed scheme determines a quality index for each video segment, based on the pixel-wise difference between the luminance planes of consecutive frames at each frame-rate, and predicts the computation needed to decode each frame using data relating frame sizes to previous decoding times. A new dynamic voltage and frequency scaling (DVFS) scheme is then invoked to achieve the specified quality index. The proposed scheme was implemented on a smartphone and a user test was conducted to assess the acceptability of different degree of frame-rate reduction. Real measurements showed that the proposed scheme uses between 5% and 41% less energy than the Linux DVFS governor used in many smartphones, while maintaining acceptable video quality.

Higher level chromatic mechanisms for image segmentation

We used a noise-masking paradigm to investigate the number and properties of chromatic mechanisms involved in image segmentation. Observers were presented with a pattern of dynamic random squares, each independently modulated along a certain direction in DKL color space, either in the isoluminant plane or in the L - M luminance plane. A signal consisting of a rectangular region of squares, oriented horizontally or vertically, was added to the noise. The signal squares were spatially and temporally aligned to the noise squares, excluding the possibility of phase offsets to mediate segmentation performance. Noise and signal color directions were independently varied, and the signal contrast was measured at which an observer could reliably indicate the orientation of the signal. In a second set of experiments, the noise was simultaneously varying in two directions, symmetrically arranged around the signal direction. Masking was generally highest when signal and noise were modulated along the same direction and minimal for orthogonal noise. No difference was found between signals modulated along cardinal directions or intermediate directions. However, measured tuning widths critically depended on the type of noise: Noise modulated along one direction results in narrow tuning, whereas two-sided noise results in broad tuning. A chromatic detection model with multiple broadly tuned mechanisms successfully accounts for the experimental findings, both for narrow and broad tuning curves. Models with four broadly tuned cardinal mechanisms or multiple narrowly tuned mechanisms failed to reproduce the data. Our results suggest an important role for multiple, broadly tuned mechanisms in image segmentation.

Comparative experiment with colour texture classifiers using the CCR feature space

An approach to grey level texture analysis is extended to colour images. Three colour texture classifiers using the CCR feature space are proposed. Textural information is derived from luminance plane by means of coordinated clusters transform along with chrominance features treated separately. The classifiers differ, basically, in the use of RGB and YIQ colour spaces. The main objective of this work is to evaluate the performance of classifiers quantitatively by means of comparative experiment on a set of VisTex and OuTex colour images. The experimental results indicate that the new classifiers are fast and at least as efficient as other texture analysis techniques evaluated on the same set of images.

Colour and luminance selectivity of spatial and temporal interactions in orientation perception

Previous studies have commented upon the similar phenomenology of simultaneous and successive interactions in the perception of orientation. These similarities have been taken as evidence of common mechanisms underlying the simultaneous tilt illusion (TI) and the successive tilt aftereffect (TAE). We measured the TI and TAE for four subjects for combinations of test and inducing stimuli modulated along either the same or orthogonal axes of colour space within the L+ M+ S, L– M colour–luminance plane. The largest TI and TAE were found when test and inducer were modulated along the same axis of colour space. The TI consistently showed greater selectivity for colour/luminance than the TAE. The results are discussed in relation to the known chromatic properties of the primate visual pathways. Specifically, we suggest that both the TI and TAE involve colour- and luminance-specific neurons in primary visual cortex as well as cue-invariant mechanisms in extrastriate cortex.

Visual-error criterion for color-image processing

We extend a new visual-error criterion for achromatic images to color images. After the tristimulus planes are transformed to a luminance-compatible color space, the achromatic-error criterion is used for the luminance plane and the squared-error criterion is used for the two chromatic planes taken together. The optimal linear estimator for the resulting color-image-error criterion is compared against a purely squared-error criterion in the task of reconstructing color images degraded by varying amounts of additive noise. The images restored with the new error criterion appeared sharper and truer in fine detail. Except for the least and most noisy cases, in which no clear preference was found, viewers of the cathode-ray-tube display unanimously preferred these restorations over the comparatively fuzzy squared-error ones, despite a grainier appearance. These results are consistent with the previous ones found with the new visual-error criterion for achromatic images only. Through this extension to color images and the good results in restoring noisy images, we have found an error criterion that shows promise for applications in color-image processing.