One interesting feature of the human visual system is the topological transformation of the retinal image into its cortical projection. The excitation of the cortex can be approximated by a log-polar mapping of the eye’s retinal image. In this tutorial paper we describe the log-polar mapping and its main properties.

Segmentation of blood vessels in retinal images is an important part in retinal image analysis for diagnosis and treatment of eye diseases for large screening systems. In this paper, we addressed the problem of background and noise extraction from retinal images. Blood vessels usually have central light reflex and poor local contrast, hence the results yield by blood vessel segmentation algorit...

The field of ophthalmology (the study of the eye) has increasingly turned to medical imaging to play an important role in diagnosing diseases. Widespread medical conditions can be identified with only pictures of the eye using computer automated processes. Determining the segmentation of the circulatory system in the eye is difficult for doctors as the task of distinguishing blood vessels by si...

Optic disk segmentation plays a key role in the mass screening of individuals with diabetic retinopathy and glaucoma ailments. An efficient hardware-based algorithm for optic disk localization and segmentation would aid for developing an automated retinal image analysis system for real time applications. Herein, TMS320C6416DSK DSP board pixel intensity based fractal analysis algorithm for an au...

Previous theories of myopia development involved subtle and complex processes such as the sensing and analyzing of chromatic aberration, spherical aberration, spatial gradient of blur, and spatial frequency content of the retinal image. However, these theories have not been able to explain all the diverse experimental results, which has been accomplished by our newly proposed incremental retina...

Starting from measured scene luminances, we calculated the retinal images of High Dynamic Range (HDR) test targets. These test displays contain 40 gray squares with a 50% average surround. In order to approximate a natural scene the surround area was made up of half-white and half-black squares of different sizes. In this display, the spatial-frequency distribution approximates a 1/ f function ...

The aim was to determine how visual acuity is affected by myopia when optical factors of the eye are controlled. Grating acuity was measured with interference fringes to avoid the effects of aberrations, and ocular biometry was used to compensate for differences in retinal image size among subjects. Distance spectacle refractions ranged from +2.25 to -14.75 D. The retinal magnification factor (...

Current computational models of smooth-pursuit eye movements assume that the primary visual input is local retinal-image motion (often referred to as retinal slip). However, we show that humans can pursue object motion with considerable accuracy, even in the presence of conflicting local image motion. This finding indicates that the visual cortical area(s) controlling pursuit must be able to pe...

Retinal images are frequently corrupted by unwanted variations in intensity that occur due to general imperfections in the image acquisition process. This inhomogeneous illumination across the retina can limit the useful information accessible within the acquired image. Specifically, this can lead to serious difficulties when performing image processing tasks requiring quantitative analysis of ...

The discovery of melanopsin-dependent inner retinal photoreceptors in mammals has precipitated a fundamental reassessment of such non-image forming (NIF) light responses as circadian photoentrainment and the pupil light reflex. By contrast, it remains unclear whether these new photoreceptors also play a role in classical image-forming vision. The retinal ganglion cells that subserve inner retin...