Chroma Space Research Articles

Quality of Aesthetic Experience and Implicit Modulating Factors

Quality of Aesthetic Experience and Implicit Modulating Factors

A multi-level tonal interval space for modelling pitch relatedness and musical consonance

In this paper we present a 12-dimensional tonal space in the context of the Tonnetz, Chew’s Spiral Array, and Harte’s 6-dimensional Tonal Centroid Space. The proposed Tonal Interval Space is calculated as the weighted Discrete Fourier Transform of normalized 12-element chroma vectors, which we represent as six circles covering the set of all possible pitch intervals in the chroma space. By weighting the contribution of each circle (and hence pitch interval) independently, we can create a space in which angular and Euclidean distances among pitches, chords, and regions concur with music theory principles. Furthermore, the Euclidean distance of pitch configurations from the centre of the space acts as an indicator of consonance.

Detecting Image Splicing Using Merged Features in Chroma Space

Image splicing is an image editing method to copy a part of an image and paste it onto another image, and it is commonly followed by postprocessing such as local/global blurring, compression, and resizing. To detect this kind of forgery, the image rich models, a feature set successfully used in the steganalysis is evaluated on the splicing image dataset at first, and the dominant submodel is selected as the first kind of feature. The selected feature and the DCT Markov features are used together to detect splicing forgery in the chroma channel, which is convinced effective in splicing detection. The experimental results indicate that the proposed method can detect splicing forgeries with lower error rate compared to the previous literature.

Research on Color Matching and Reproduction on Aluminum Foil Packaging Materials

The effects of aluminum foil packaging materials on color reproduction were mainly studied from the following two aspects in this topic: (1) through the study of CIEl976 chroma space, color difference evaluations of 7 kinds of colors for aluminum foil were compared with that of coated paper, based on the established color libraries of coated paper. (2) Four different spectrophotometers of X-Rite were used to measure L*、 a*、 b* of different colors, analyzing the effects of different spectrophotometer on color reproduction. Research has proved that: (1) the method which color was transferred to the aluminum foil, according to the established color libraries of coated paper, is feasible, and there was no difference between two colors on aluminum foils by visual inspection, the chromatic aberration was less than 1. (2) From the measurements, aspheric photometers like X-Rite939, Spectroeye, X-Rite500 cannot be used for color measurement on aluminum foil, the error is bigger than SP64, and accuracy is lower. (3) Through the total color difference analysis of four instruments on magenta, the ball SP64 portable spectrophotometer is the most suitable equipment for color reproduction on aluminum foil packaging materials.

Area assessment of psoriasis lesions for PASI scoring

Psoriasis is a skin disorder which is caused by a genetic fault. Although there is no cure for psoriasis, there are many treatment modalities to help control the disease. To evaluate treatment efficacy, the current gold standard method, PASI (Psoriasis Area and Severity Index), is used to measure psoriasis severity by evaluating the area, erythema, scaliness and thickness of the plaques. However, the determination of PASI can be tedious and subjective. In this work, we develop a computer vision method that determines one of the PASI parameters, the lesion area. The method isolates healthy and healed skin areas from lesion areas by analysing the hue and chroma information in the CIE L*a*b* colour space. Centroids of healthy skin and psoriasis in the hue–chroma space are determined from selected sample. The Euclidean distance of all pixels from each centroid is calculated. Pixels are assigned to either healthy skin or psorasis lesion classes based on the minimum Euclidean distance. The study involves patients from different ethnic origins having three different skin tones. Results obtained show that the proposed method is able to determine lesion areas with accuracy higher than 90% for 28 out of 30 cases.

Restoring subsampled color images

In some capturing devices, such as digital cam- eras, there is only one color sensor at each pixel. Usually, 50% of the pixels have only a green sensor, 25% only a red sensor, and 25% only a blue sensor. The problem is then to restore the two missing colors at each pixel - this is called demosaicing, because the original samples are usu- ally arranged in a mosaic pattern. In this short paper, a few demosaicing algorithms are developed and compared. They all incorporate a notion of smoothness in chroma space, by imposing conditions not only on the behavior of each color channel separately, but also on the correlation between the three channels.