Robert Ennis; Katja Doerschner

The color appearance of curved transparent objects

publication date
May 2021
see more


Studies on colored transparent objects have elucidated potential mechanisms, but these studies have mainly focused on flat filters overlaying flat backgrounds. While they have provided valuable insight, these studies have not captured all aspects of transparency, like caustics, specular reflections/highlights, and shadows. Here, we investigate color-matching experiments with curved transparent objects for different matching stimuli: a uniform patch and a flat filter. Two instructions were tested: simply match the color of the glass object and the test element (patch and flat filter) or match the color of the dye that was used to tint the transparent object (patch). Observers’ matches differed from the mean, the most frequent, and the most saturated color of the transparent stimuli, whereas the brightest regions captured the chromaticity, but not the lightness, of patch matches. We applied four models from flat filter studies: the convergence model, the ratios of either the means (RMC) or standard deviations (RSD) of cone excitations, and a robust ratio model. The original convergence model does not fully generalize but does not perform poorly, and with modifications, we find that curved transparent objects cause a convergence of filtered colors toward a point in color space, similar to flat filters. Considering that, the RMC and robust ratio models generalized more than the RSD, with the RMC performing best across the stimuli we tested. We conclude that the RMC is probably the strongest factor for determining the color. The RSD seems instead to be related to the perceived “clarity” of glass objects.


Observers readily answer the question, “What is the color of this transparent object?” regardless of whether the matching element is a uniform patch or a flat transparent filter. In both cases, their responses differ from the mean chromaticity of the Glaven, as well as its most saturated color and its most frequent color, while the White Point almost captures the uniform patch match but falls short of explaining the lightness of their settings. At least for a flat filter matching element, observer responses are the result of a color constancy-esque discounting operation. More accurately, we can say that the ratios of the mean cone excitations (RMC) between the filtered and unfiltered regions are most likely what observers are matching, and it could be what they use to extract the point and magnitude of the convergence induced by a transparent object. However, other sources of information could be at play, which might correlate with or trade off with the RMC, and more work will be needed to determine their effects, as well as any Gestalt principles at work and how eye movements are used to sample the relevant information. At the least, though, our results support the conclusion that the RMC has a substantial effect on the color of a transparent object.


  • Vision therapy is well worth the response, time and effort. Our Son had a hard time focusing and writing neatly. After vision therapy Seth could complete a task in half the time if previously took. His abilities to focus improved greatly and so did his handwriting.

    Also, he was better at listening. As a parent, we wanted learning to be fun for our Son, and vision therapy made this possible.

    Amanda T.

  • Vision Therapy is well worth the expense, time and effort. Our son had a hard time focusing handwriting neatly. After vision therapy Seth could complete a task in half the time it previously took his abilities to focus and improved greatly and so did his handwriting.

    Also, he was better at listening. As a parent you wanted learning to be fun for our son and vision therapy made this possible.

    Alexa H.

  • Vision Therapy has given or son the tools he needs to be able to scan and read the written word more effectively and efficiently.

    He love working with John and these working sessions give him the motivation to gladly work on his homework assignments.

    It amazed us to see the difference in the tracking of his eyes and along a line of it's from the beginning to the end of the treatment.

    Dr. McBryar , Kristen and John  are all marvelous and we would recommend them to anyone I only wish that we would have found them sooner!

    Charlotte M.

  • Prior to coming to the institute for vision development my son complained of daily headaches. Therapy has eliminated his headaches completely. I love knowing my son is able to learn pain-free for the rest of his life because of the work that has been done over just a few weeks in this office. He he absolutely loved coming that didn't even feel like going to a doctor or therapy. We are grateful for the relief he was able to find by coming here.

    Thank you!

    Olivia C.

  • Seems much less frustrated with life

    Reads non-stop and fast

    Spelling abilities have been hugely improved

    Seems much more confident

    Thank You!!!

    Kelly O.



Vision Among Us

One of the challenges with visual impairments and visual deficits is that it's difficult to detect them just by looking […]

Read More

Vision Therapy for Neurological Conditions

Each year an estimated 1.5 million Americans sustain a traumatic brain injury (TBI). According to the Neuro Optometric Rehabilitation Association, […]

Read More

Vision Therapy for Adults

Adults generally accept changes in themselves as part of aging, and think that there's nothing they can do about it. […]

Read More
see all blogs

Contact Us To Amplify Your EyeCare

Working Hours

Monday - Thursday
8:00 am - 5:15pm
1043 Executive Drive Suite #101 Hixson, TN 37343
Website Accessibility Policy
Safety protocols page
phone-handsetarrow-uparrow-right linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram