To determine whether speed discrimination improves when the retinal image is stabilized against the effects of eye movements, thresholds were measured under stabilized and normal viewing conditions. In the normal viewing conditions, eye movements were recorded and used to estimate retinal-image speeds. Stimulus reference speed for sinusoidal gratings varied from 0.5 to 8.0 deg/sec. Results show...

McCloskey and a team of authors (1995) documented a fascinating deficit involving the localization of objects. When subject A.H. reaches for objects placed in different positions, she is often wrong about direction but not amount. An object located 30° to her left, say, might cause her to reach 30° to the right. The authors demonstrated that her motor abilities are flawless and that the errors ...

PURPOSE We developed and evaluated the performance of a novel computer-based image analysis system for grading plus disease in retinopathy of prematurity (ROP), and identified the image features, shapes, and sizes that best correlate with expert diagnosis. METHODS A dataset of 77 wide-angle retinal images from infants screened for ROP was collected. A reference standard diagnosis was determin...

Analysis was undertaken of the retinal image characteristics of the best-spectacle corrected eyes of progressing myopes (n = 20, mean age = 22 years; mean spherical equivalent = -3.84 D) and a control group of emmetropes (n = 20, mean age = 23 years; mean spherical equivalent = 0.00 D) before and after a 2h reading task. Retinal image quality was calculated based upon wavefront measurements tak...

BACKGROUND The diagnosis of plus disease in retinopathy of prematurity (ROP) largely determines the need for treatment; however, this diagnosis is subjective. To make the diagnosis of plus disease more objective, semi-automated computer programs (e.g. ROPtool) have been created to quantify vascular dilation and tortuosity. ROPtool can accurately analyze blood vessels only in images with very go...

UNLABELLED Even when we view an object from different distances, so that the size of its projection onto the retina varies, we perceive its size to be relatively unchanged. In this perceptual phenomenon known as size constancy, the brain uses both distance and retinal image size to estimate the size of an object. Given that binocular disparity, the small positional difference between the retina...

The location of the optic disc is of critical importance in retinal image analysis. We improve on past approaches on optic disc detection by working in colour space and also by localising accurately the optic disc boundary using an automatically initialised snake. The key issue presented is a comparison of colour spaces for performing colour morphology to remove blood vessels and prepare the im...

The blood vessel detection and segmentation technique plays a useful clinical role in an automated retinopathy analysis system. But manual segmentation of vessels requires expertise. It is a very tedious and time consuming task. Employing computational intelligence for this purpose would help in efficient retinal analysis. An user friendly graphical user interface (GUI) that is MATLAB based too...

Accurate segmentation of retinal blood vessels is an essential task for diagnosis of various pathological disorders. In this paper, a novel method has been introduced for segmenting retinal blood vessels which involves pre-processing, segmentation and post-processing. The pre-processing stage enhanced the image using contrast limited adaptive histogram equalization and 2D Gabor wavelet. The enh...