The 68th Symposium of the Society for Science on Form was held in November 2009 at Dokkyo Medical University, Japan. A special issue, titled, "Special Issue: Form on Biosystems and Functions," which is a collection of papers presented at the symposium as well as newly contributed papers related to the symposium theme, has been published. In particular, it is comprised of two reviews, six original papers, and two letters. Its contents cover aspects of form such as stereoscopic vision and displays, color sense tests, lens accommodations, reducing noise in X-ray images, scales of lepidopteran insects, and the structural color of earthworms.

On behalf of the editorial team, we offer our sincerest apologies for the delayed publication of this issue. The after effects of the Great East Japan Earthquake and personal health issues prohibited us from publishing this issue in a timely manner.

It is our hope that this issue contributes to future advancements in the Society for Science on Form.

Color defectives have been considered to be handicapped persons in modern-day Japan. We studied color recognition of color detectives using various clolor materials and color-blindness test. At first, a traffic signal recognition were reviewed. There were no significant differences between the color defectives and the controls. It is a distinct advantage for color detectives that the actual color of the green traffic signal light is mostly blue-green in Japan. The second and third reviews were related to the Color Mate Test (CMT) and its comparison with other color vision tests. The CMT was developed specifically to know which children will require special color consideration in classroom activities, but the Ishihara Color Charts and the Farnsworth D-15 Test (Panel D-15) continue to be used with greater frequency. CMT is the most accurate measure of color discrimination ability in daily life, followed by the Panel D-15. The Ishihara test should be considered unsuitable for evaluating color discrimination ability in daily life. When there is a need to evaluate real-life color discrimination ability, evaluations using common colored objects are the most appropriate.

Wing surfaces of most lepidopteran insects (butterflies and moths) are covered with abundant scales. Most scales are classified into two kinds, called cover and basal scales, which are overlapped each other to make the layered structure on the wing surface. The detailed morphology, functions, and development of this layered structure are reviewed and discussed.

The epidermis of an earthworm has a log-pile structure of fibers, and exhibits a structural color. The structure is considered as a photonic crystal. Optical properties of the epidermis of an earthworm have been investigated numerically by means of the analogy of the photonic crystal. The numerical method employed here is the periodic fast multipole method. The structural color is reproduced with the RGB color from the reflection spectrum. The reflection spectrum and the reproduced color are compared with those by a multilayer model and it is confirmed that the treatment as a photonic crystal is important.

Human beings begin to lose the ability to control muscles with advancing age. A reduction in the function of flexor muscles is observed in the case of the elderly when they experience a fall. The flexor muscles around the hip joint include femoral rectus and abdominal muscles. Recently, there has been an increasing focus on biofeedback training (BFT), which is expected to improve the ability to control muscles and prevent the deterioration of muscular functions due to aging. In this study, we performed surface electromyography (sEMG) of the femoral rectus muscles during the BFT of a dominant leg. This study aimed at developing indices for form in a smoothed sEMG and evaluating the changes in these indices with age. Statistical analysis indicated that it was necessary to include the time constant of the exponential decay curve fit to maximal points during prolonged muscular contraction. A reduction in the ability to control muscles owing to aging can be detected by performing sEMG during BFT by using a time constant. This time constant will be applied to evaluate the effect of BFT on recovery of the ability.

Image noise may prevent proper diagnostic X-ray imaging. This study is aimed at developing new noise rejection methods using a mathematical model that describes the form of X-ray image noise. Stationary noise is one type of noise found in X-ray images. Stationary noise is nonstochastic and appears independent of the radiographic factors. In this paper, we verify methods for identifying stationary noise using a polynomial regression model, and extracting such noise from X-ray images obtained from a CR system. The results of this study demonstrate that stationary noise can be extracted with high precision using a particular low-pass filter frequency. We found that a regression model for greater than second-degree polynomials can be applied for roughly identifying stationary noise. However, the fitting accuracy of the regression curve is not significantly improved in terms of the amount of multiplication required when increasing the degree of the polynomial regression model.

In soft-copy diagnosis, each pixel of an X-ray detector is displayed as the corresponding pixel of a liquid crystal display (LCD). However, when a mammographic image is displayed on an LCD for the first time, the entire image is reduced. We examined the influence of differences in LCD image-reduction rates on the signal-detection performance by observational experiments. We created a simulated image similar to Burger's phantom and reduced it by using the nearest neighbor, bilinear, and bicubic interpolation methods. We displayed the reduced images on LCDs with different numbers of pixels and examined the signal-detection performance with each interpolation method. The signal-detection performance deteriorated as the image-reduction rate increased irrespective of the interpolation method. Among the interpolation methods, the nearest neighbor method resulted in the worst signal-detection performance, and the bilinear method was the most suitable for image reduction. Mammographic images are mostly reduced for viewing on an LCD. Such reduction changes the appearance of microcalcifications. Therefore, depending on their size and distribution, microcalcifications observed in these images may be missed on an LCD.

In the present study, we examined the visual accommodation of subjects who were gazing fixedly at stereoscopic images on two different displays: a cathode ray tube (CRT) with the subjects wearing liquid crystal shutter glasses and a liquid crystal display (LCD) with the subjects not wearing liquid crystal shutter glasses. In Experiment 1, we measured accommodation in subjects viewing a moving stereoscopic image. In Experiment 2, we measured accommodation in subjects viewing moving stereoscopic images on an LCD and a CRT. In Experiment 3, we measured accommodation in subjects viewing a stereoscopic image moving from far to near on an LCD. In Experiment 4, we measured of accommodation in subjects viewing moving stereoscopic images (stereoscopic display mode) and non-stereoscopic images (2-D mode) on an LCD.

The results suggested, the ciliary muscle is repeatedly strained and relaxed while the subject views the moving target. In the present study, the subjects' accommodative amplitude was changed when the target moved from the near to far point, and vice versa.

The visual function of lens accommodation was measured while subjects used stereoscopic vision with a head mounted display (HMD). Eyesight while viewing stereoscopic Landolt ring images displayed on HMD was also studied. Accommodation to virtual objects was seen when subjects viewed stereoscopic images of 3D computer graphics, but not when the images were displayed without appropriate binocular parallax. This suggests that stereoscopic moving images on HMD induced visual accommodation. Accommodation should be adjusted to the position of virtual stereoscopic images induced by parallax. A difference in the distances of the focused display and stereoscopic image may cause visual load. However, an experiment showed that Landolt rings of almost the same size were distinguished regardless of virtual distance of 3D images if the parallax was not larger than the fusional upper limit. The results of this study suggest that stereoscopic moving images on HMD induced visual accommodation by expansion and contraction of the ciliary muscle, which was synchronized with convergence. Appropriate parallax of stereoscopic vision should not reduce the visibility of stereoscopic virtual objects.

Accommodation and convergence were measured simultaneously while subjects viewed 2D and 3D images. The aim was to compare fixation distances between accommodation and convergence in young subjects while they viewed 2D and 3D images. Measurements were made three times, 40 seconds each, using 2D and 3D images. The result suggests that ocular functions during viewing of 3D images are very similar to those during natural viewing. Previously established and widely used theories, such that within a VR system eyes must maintain accommodation on the fixed LCD screen, may need to be corrected.

Human beings can perceive that objects are three-dimensional (3D) as a result of simultaneous lens accommodation and convergence on objects, which is possible because humans can see a single so that parallax occurs with the right and left eye. Virtual images are perceived via the same mechanism, but the influence of binocular vision on human visual function is insufficiently understood. In this study, we developed a method to simultaneously measure accommodation and convergence in order to provide further support for our previous research findings. We also measured accommodation and convergence in natural vision to confirm that these measurements are correct. As a result, we found that both accommodation and convergence were consistent with the distance from the subject to the object. Therefore, it can be said that the present measurement method is an effective technique for the measurement of visual function, and that even during stereoscopic vision correct values can be obtained.