Advances in imaging and display engineering have given rise to new and improved image and video applications that aim to maximize visual quality under given resource constraints (e.g., power, bandwidth). Because the human visual system is an imperfect sensor, the images/videos can be represented in a mathematically lossy fashion but with enough fidelity that the losses are visually imperceptible—commonly termed “visually lossless.” Although a great deal of research has focused on gaining a better understanding of the limits of human vision when viewing natural images/video, a universally or even largely accepted definition of visually lossless remains elusive. Differences in testing methodologies, research objectives, and target applications have led to multiple ad-hoc definitions that are often difficult to compare to or otherwise employ in other settings. We present a compendium of technical experiments relating to both vision science and visual quality testing that together explore the research and business perspectives of visually lossless image quality, as well as review recent scientific advances. Together, the studies presented in this paper suggest that a single definition of visually lossless quality might not be appropriate; rather, a better goal would be to establish varying levels of visually lossless quality that can be quantified in terms of the testing paradigm.
Purpose: The study evaluated the accuracy of depth perception afforded by static and dynamic stereoscopic three-dimensional (S3D) images with proportional (scaled to disparity) and constant size cues. Methods: Sixty adult participants, 18 to 40 years (mean, 24.8 years), with good binocular vision participated in the study. For static S3D trials, participants were asked to indicate the depth of stationary S3D images rendered with 36, 48 and 60 pixels of crossed disparity, and with either proportional or a constant size. For dynamic S3D trials, participants were asked to indicate the time when S3D images, moving at 27, 32 and 40 pixels/sec, matched the depth of a reference image which was presented with 36, 48 and 60 pixels of crossed image disparity. Results: Results show that viewers perceived S3D images as being closer than would be predicted by the magnitude of image disparity, and correspondingly they overestimated the depth in moving S3D images. The resultant depth perception and estimate of motion speed were more accurate for conditions with proportional and larger image size, slower motion-in-depth and larger image disparity. Conclusion: These findings possibly explain why effects such as looming are over stimulating in S3D viewing. To increase the accuracy of depth perception, S3D content should match image size to its disparity level, utilize larger depth separation (without inducing excessive discomfort) and render slower motion in depth.
KEYWORDS: Eye, Target detection, 3D image processing, Visualization, Diamond, 3D image enhancement, Stereoscopic displays, Signal detection, 3D acquisition, Eyeglasses
Purpose: Stereoscopic three-dimensional (S3D) viewing enhances depth perception of two-dimensional (2D) images.
The present study measured viewer’s ability to discern depth differences and depth change afforded by image disparities presented on an S3D display. Methods: Sixty adults (age 24.8 +/- 3.4 years, 28% male) with binocular acuity better than 20/25 and stereoacuity better than 60 arcsec viewed test images presented on a 55” 3D TV (1920 x 1080 pixels) at 2.4m distance. In each trial, three of the four circles in the test image were with the same crossed baseline disparity of 12, 24, 36, 48, and 60 pixels, and the other (target) circle with added crossed disparity (delta disparity) of 2, 4, and 6 pixels. A subsequent change in delta disparity of the target circle (+/-2 pixels) was presented. Participant's response time and accuracy for identifying the target circle and its direction of depth change, as well as their vergence eye position, was recorded. Results: Larger baseline disparity resulted in lower accuracy and longer response times in identifying the target circle. The change of delta disparity was more accurately discerned when the delta disparity was larger and the change resulted in increased crossed disparity. Direction of vergence change and the final vergence error reflected an averaging of screen and image depths. Conclusion: S3D-induced depth difference and motion in depth is more easily discerned with smaller crossed disparity for background objects (< 43.3 arcmin or 48 pixels) and larger separation between image disparities (>3.6 arcmin or 4 pixels).
KEYWORDS: 3D acquisition, Visualization, 3D vision, 3D displays, 3D image processing, Eye, 3D visualizations, Stereoscopic displays, Optical tracking, Computer programming
Vergence and accommodative responses in viewing near objects in the real world are behaviorally coupled to maintain
clarity and singularity for the object of regard. However virtual stereoscopic stimuli, such as in 3D displays, create non-normal
coupling that may cause improper vergence and accommodative responses, possibly resulting in visual
discomfort. The present study examined whether the dynamic aspect of current 3D displays is the underlying cause of
visual and physical discomfort. To this end, subjects' vergence and accommodative responses were measured while
they tracked an approaching 2D or 3D target, and while watching a 2D or 3D movie. The tracking target either moved
in steps or continuously, and it was either clear or intentionally blurred. Results show that convergence insufficiency
and improper accommodation were greater when a 3D target was moving continuously toward the near position
compared to a 2D target and a 3D stimulus moving in steps. Clear targets also resulted in greater vergence and
accommodative responses than blurred targets. Viewing 3D movie resulted in greater vergence and accommodation, as
well as more severe vision- and motion-related discomfort than 2D movie. These findings suggest that with 3D displays,
disparity-induced vision difficulty and internal conflicts cause perceived visual and motion-related discomfort.
Characteristics of 3D stimuli, such as the frequency and amplitude of target motion, likely critically affect the severity of
reported discomfort symptoms.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.