A non-destructive method of estimating the freshness of fish is required for appropriate price setting and food safety. In particular, for determining the possibility of eating raw fish (sashimi), freshness estimation is critical. We studied such an estimation method by capturing images of fish eyes and performing image processing using the temporal changes of the luminance of pupil and iris. To detect subtle non-visible changes of these features, we used UV (375 nm) light illumination in addition to visible white light illumination. Polarization and two-channel LED techniques were used to remove strong specular reflection from the cornea of the eye and from clear-plastic wrap used to cover the fish to maintain humidity. Pupil and iris regions were automatically detected separately by image processing after the specular reflection removal process, and two types of eye contrast were defined as the ratio of mean and median pixel values of each region. Experiments using 16 Japanese dace (Tribolodon hakonensis) at 23℃ and 85% humidity for 24 hours were performed. The eye contrast of raw fish increase non-linearly in the initial period and then decreased; however, that of frozen-thawed fish decreased linearly throughout 24 hours, regardless of the lighting. Interestingly, the eye contrast using UV light showed a higher correlation with time than that using white light only in the case of raw fish within the early 6- hour period postmortem. These results show the possibility of estimating fish freshness in the initial stage when fish are eaten raw using white and UV lightings.
An endoscopic image processing technique for enhancing the appearance of microstructures on translucent mucosae is described. This technique employs two pairs of co- and cross-polarization images under two different linearly polarized lights, from which the averaged subtracted polarization image (AVSPI) is calculated. Experiments were then conducted using an acrylic phantom and excised porcine stomach tissue using a manual experimental setup with ring-type lighting, two rotating polarizers, and a color camera; better results were achieved with the proposed method than with conventional color intensity image processing. An objective evaluation method that uses texture analysis was developed and used to evaluate the enhanced microstructure images. This paper introduces two types of online, rigid-type, polarimetric endoscopic implementations using a polarized ring-shaped LED and a polarimetric camera. The first type uses a beam-splitter-type color polarimetric camera, and the second uses a single-chip monochrome polarimetric camera. Microstructures on the mucosa surface were enhanced robustly with these online endoscopes regardless of the difference in the extinction ratio of each device. These results show that polarimetric endoscopy using AVSPI is both effective and practical for hardware implementation.
This paper describes a novel image processing method for endoscopy that enhances the appearance of microstructures on mucosa. The new technique employs two pairs of parallel- and crossed-nicols polarimetric images, from which an averaged subtracted polarization image (AVSPI) is calculated. Experiments were first executed using a manual experimental setup with ring-type lighting, two rotating polarizers and a color camera. A new objective evaluation method that uses texture analysis (GLCM) was developed and applied to evaluation of the enhanced microstructure images. Experiments using excised porcine stomach tissue showed better results than with conventional color intensity image processing. Next, an online rigid-type polarimetric endoscope system using a polarized ring-shaped LED and a special three-CCD color polarimetric camera was developed. The two types of equipment described above are quite different as to extinction ratio values, but show similarly enhanced image quality. Our results show that polarimetric endoscopy is not only effective but also practical for hardware implementation.
Recently the color reproduction of the real objects is becoming more and more important in the field of telemedicine and internet shopping. To reproduce the object's color under the various conditions, the surface spectral reflectance has to be estimated. In this paper we present the novel way to estimate it using conventional 3- band digital camera. Usually the precise estimation of the spectra from the 3-band image is very difficult, as it has metameric black and the simple camera model is not suitable. To improve the estimation accuracy, we propose dividing color space in to clusters and estimating spectra using different model parameters at each cluster. Clusters are set corresponding to the major objects in camera images. Next the estimated spectral image is reproduced on the monitor. When luminance and color temperature of the specified viewing illuminant and the monitor are different, the subject hardly perceives the object's real color. Therefore the image is converted using CIECAM97s. This paper shows the results of simulation using the image of enlarged human's mouth assuming remote consulting with dental clinic. In this system, a dentist can perceive the real color of patient's gums and teeth on the monitor.
This paper has two objectives. The first is to explain our color reproduction procedure, especially our new gamut check and mapping method and comparative experimental results on it. The second is to discuss availability and effectiveness of multilayer perceptron (MLP) in the color reproduction fields. We will show problems and merits of MLP and its learning through experiments.
This paper describes the theoretical estimation of errors caused by 3D table interpolation for nonlinear color conversions. The interpolation accuracy is affected by three factors; geometric interpolation techniques, distance between the lattice points included in the 3D table, and the degree of nonlinearity of the color conversion. This paper focuses its point on the nonlinearity. Two types of error; conventional error and ripple artifact error are defined, and gray gradation is used for input image. Four types of nonlinear color conversions categorized into ripple type or nonripple type are tested using trilinear interpolating technique. The error goes down with the decreasing of d, however local gamma conversion has very large ripple that couldn't go down with decreasing of d.
We present a novel color processor with programmable
interpolation by small memory (PRISM). The input/output signals to/from the devices are flexibly converted by a 3-0 look-up table (LUT) with a PRISM interpolator. The PRISM architecture provides a simple computation algorithm with sufficient accuracy. The performance of PRISM interpolation is compared with other conventional methods. In practice, PRISM is less complicated than CUBE
and PYRAMID, and more accurate than PYRAMID and
TETRAHEDRON. PRISM cuts the memory size of LUT drastically to an orderof iO compared with a full-size LUT method and brings with it a large-scale integration color processor operating at a higher
than video rate. The PRISM structure is the most suitable for the perceptual color spaces such as YCrCb or CIELAB and very useful for device-independent color reproduction and transmission. Typical applications by a PRISM color processor are presented.
Proc. SPIE. 1244, Image Processing Algorithms and Techniques
KEYWORDS: Detection and tracking algorithms, Image processing, Scanners, Control systems, Printing, Color reproduction, 3D image processing, Evolutionary algorithms, RGB color model, Color and brightness control algorithms
We propose a new algorithm available to variety of real-time color space
transformations : color correction for hardcopy system, perceptual color
control in CIE-LAB space, color coordinate conversions, and color
recognition. This algorithm consists of color look up tables and a new 3D
color space interpolator. This interpolator makes it easy to design a simple
real-time color processor. The simulation shows how the flexible
transformations can be performed without degrading the color and tone.