Science topics: MedicinePhysiologyNeurophysiologyVisionColor Vision
Color Vision - Science topic
Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of RETINAL CONE PHOTORECEPTORS with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).
Questions related to Color Vision
Human cones in the retina decipher the colors through an additive system that involves differential stimulation of three kinds of cones. Do color tests such as Fransworth Munsell 100 hue test or its online variants use a subtractive system? And why so many non-spectral hues?
lanthony d15 desaturated color vision testing
I’m searching for a researcher / research group who is working on behavioural tests – colour discrimination in birds of prey. I would be very grateful for advice and hints! Best, Dominique
Mantis shrimp are known to have up to 16 different types of cones, polarized vision, and are the only animals known to detect circularly polarized light. I would be interested in hearing from anybody doing research on how their vision works and more importantly -why?
I would like to ask a question upon request of my student:
I am a student and I am doing a project on a very interesting topic: why men and women perceive colors differently. But I am having a lot of trouble finding information. In various sources, the material is not available or is very unclear to an average student.
The only things that I’ve found were the eye anatomy and a physiological explanation (Bimler, 2004) that genes determine the perception of colors thus women heterozygous for opsin genes see colors better than other women and men.
I will be very happy to get some help and get an explanation of this human feature.
I am working with colour patterns of a flower pollinated by Centris sp.. But I have difficulty in find their photorreceptor sensibilities to run the colour vision models. Thanks!
There is a overall convergence of receptors through bipolar cells on ganglion cells is about 105:1 at retina.however beyond that point divergence is seen ( in the visual cortex the number of neurons concerned with vision is 1000 times the number of fibers in the optic nerves). Does this curtail the information send to cortex and enhance the processing at cortical level ?
It is known fact that the stabilized retinal image (spatially and temporally) will disappear in seconds. What will happen if we illuminate the spatially stabilized scene (e.g. experiment described in , Fig.33) with a flickering light at some frequency? I guess with low frequency the retina will "recognize" the scene as non-stabilized in time and the image perception will not disappear.
So the question is about the cut-off frequency of the flickering light?
I think at certain frequency the retina should recognize it as temporally stable and the image will disappear as normally do when the illuminating light is continuous.
Does anyone know some study on this matter?
Do you have an idea about the source of light through which we see dreams ? and what is the source of light through which we can see the colors we see in dreams?
I wish you all the best
Gabor patches are used in psychophysic experiments to study selective responses of the visual system. What i want to understand is how the color stimulus is generated and how color modulation is obtaneid. (i.e. do we multiply the sinus or the exponential of chromaticity or intensity or which value related to color description? )
Thank you for your interest.
I am looking for solutions to match stimuli according to color scheme/palette. Say I have an image set A with 200 images. I now want to compile another image set B that roughly follows the same colour statistics, i.e. each image in set A should get a sibling in set B with similar colour proportions. For example, image A and image B should share the 10 most dominant colours. I am aware of the TinEye MulticolorEngine for color extraction and the multicolr: search by color online application and am ideally looking for a combination, i.e. using set A as an input, have a batch analysis of palette and then use this result as input for a color search. As I am not an expert in colour vision, I greatly value any input or pointers.
Thank you very much!
The inclusion of color vision tests could be easily integrated in the primary school agenda, although the best time to be used could be discussed. Amblyopia is a central issue in children eye health that needs early detection. The aim is also to explore what could be the benefits to target both conditions in school health programs. The evidence I found does not seem to support the idea:
Thanks for your comments
I'm working on the attentional selection and I wish to create a visual search task with two salient distractors, but different in saliency intensity (dark red vs. light red) surrounded with green stimuli. However, I need an equiluminant display (I'm working with EEG). How can I deal with this problem?
Is there any technique in order to change the saliency without changing the luminance intensity?
I have been explaining the physiological explanation for color afterimages for many years. What is the functional-evolutionary explanation for that physiological system? If the function is contrast enhancement, why the particular arrangement of complementary colors?
At the moment if I needed to analyse the colour of a flower, painted surface, insect trap, etc. I'd use an Ocean Optics/Avantes type desk-top spectrometer with a good light source to get an accurate reading of the reflectance from 300 to 700nm, as per Chittka & Kevan (2005). I'm increasingly seeing hand-held spectrometers for sale that claim to be accurate, and certainly seem compelling from a usability/practicality point of view. Has anyone calibrated them for accuracy against one of the desk-top models, and/or checked the spectral composition of their inbuilt light-source (if they have one at all)? Are they still calibrated properly against a BaSO4 standard? Or do these tend to work as an uncalibrated absolute measurement of whatever they're reflecting back, with no accounting for light source?
I have collected spectra using a spectrophotometer and can see which wavelengths of light are absorbed/transmitted, but how do I translate this to a single colour?
I have also converted the absorbance values at each wavelength to RGB and HSV values, so, if easier, is there a way to combine RGB/HSV values to one resultant colour value?
I am starting using the HRR colour vision test. I have already found that sometimes you find screening plates abnormal, but then the rest of the test is normal. How do you interpret that? Is that patient's colour vision normal or abnormal?
like voltage values to RGB ( 255,255,255) values.
Can it be made linear? E.g. is 0.25 to 0.5 to 0.75 gray equidistant?I want to know if there is any research regarding this issue in humans or animals. My intention is to make two absolutely distinct colours for a sheep, then make 3 intermediate (and more important, equidistant) colours, one of those 3 having the maximum ambiguity between the first 2.
I study that how the color is processed. There are a lots of study that color is processed in retina. I would like to know how color is processed in brain(like V1,V2,V3...). I know there are not studied clearly , so are there the survey like these?
Many of the color vision deficiency screening tests are available online and offline in software forms like Ishihara Tests and/or Farnsworth-Munsell Test. Is there any difference in their specificity and sensitivity while using in soft form rather than hard copy.
Ethambutol is a bacteriostatic drug used to treat colour-blindness. It is reported that red-green colour-blindness is produced in patients taking Ethambutol.
Can anyone help me to understand this mechanism?
To convert to rg Chromaticity from RGB is fantastically simple:
r' = R/(R+G+B)
g' = G/(R+G+B)
b' = B/(R+G+B)
There is now no luminance value, I would like to further remove the saturation from each element in the hopes to end up with a three-component hue value.
r'' = f(r', r'g'b')
g'' = f(g', r'g'b')
b'' = f(b', r'g'b')
Does anyone know of how to approach this? Chromaticity is both hue and saturation so there must be a way, something that does not end up with the HSL/HSV single-value hue. I know CIE Lab gets to hue from atan2(b,a) but again it is a single-value in degrees (0-360).
Hello , I'm working on Color Blindness Assistive Technologies research. We have tested about 567 subjects by both clinical standard Color Vision Deficiency (CVD) tests and a Computer Generated test. The objective of this study to prove the ability of using computer systems in screening. The aim is to use available technologies as computers and mobiles for CVD diagnosis in home, schools or even in clinics in hard times. This is the link of our 1st paper:
The question is , I need more evaluation methods rather than binary classification (sensitivity, specificity ,..) and t-test. Any recommendations?
Conference Paper An Evaluation of Computer Based Color Vision Deficiency Test...
I have seen conversions into LMS from XYZ and RGB, but because of device-dependent conversions there are many different matrices out there for it. I'm converting to LMS then changing the L,M,S values with offsets then converting back to RGB for display. I get very similar outputs with LMS and XYZ:
LMS: L(-/+ green/magenta), M(-/+ magenta/green), S(-/+ yellow-green/blue)
XYZ: X(-/+ green/magenta), Y(-/+ magenta/green), Z(-/+ orange/cyan)
Should this be the case? I felt like increasing M would effect the overall luminance more dominantly and that S would act vastly different to L+M (which I guess it does).
Does anyone know the original paper introducing the LMS colour-space or one reviewing it well?
I'd like to study color vision in some species of Gibbons through behavioral test. I'd like to confirm whether operant associative learning can be applied as a method here? or is there any better method?
We are using the Farnsworth-Munsell 100 Hue Color Vision Test for studying the quality of human colour vision and found that there are differences between left and right eye. In some people only small but in others huge. I was trying to find some articles about this but I was short of luck. Can you suggest me some?
I am working upon Genetic Epidemiology, Risk factors and Identification of Color Blindness in Different Isonym Groups of Pakistan. I will like to know about all the risk factors of Deficient Color Vision either genetic or acquired.
There is pre-defined color mapping in Yxy color space but I want to manually assign color in xy plane. How this can be done using MATLAB?
I´m not a color expert, but I am interested in knowing what is the minimum color change that the human eye can detect in CIELAB units, Delta L, Delta a*, delta B* and delta E? Can anyone give me some references?
I am trying to write a simple program which should take a normal image and convert its colors to the similar colors that a specific bird can see. The only interest here is the color, the way a bird (like european starling) can see them, not the perception which is made in the animals brain. Basically the question is, what will we see if we take a bird eyes?
I want to use this comparision http://www.webexhibits.org/causesofcolor/images/content/Absorption_peaks.jpg to write a mapping program. Could anybody suggest me how to find a mapping function using that?
I am interested in pollinator foraging decisions. Having an answer to the above question would be very helpful in interpreting some of my data
I am using luminance equated color stimuli using the standard RGB equation Lum=R*0.299+G*0.587+B*0.114. However, my pilot study shows that the resulting colors are not equally salient. Does anyone have any suggestions? If anyone has good color pairs which have been tested to be equally salient and can send a citation that would be perfect.
The UniSpec-SC is usually used in plant leaf measurements but if it is able to measure Total Reflectance it is possible to use it in any surface, or is it calibrated exclusively to plants? If so, could I adapt it somehow to measurements of animal skin?
To get an RGB representation of a wavelength of human visible spectrum there is a well known algorithm from Dr. Bruton which is pretty well known in the Internet. The original webpage is available here: http://www.physics.sfasu.edu/astro/color/spectra.html
This algorithm is based on values which is shown here(direct link to the page's image):
There is also a research paper focused to convert a wavelength to RGB, titled as "From Wavelength to RGB Filter" and is available here:
This research uses the same illustration as basic of it's functions to calculate RGB values. Both algorithms are similar and are implemented in different languages.
But what I did not understand is that in both above mentioned solutions it is not clear how the functions of the wavelength (which is illustrated as an image) is calculated. I need to know this because I want to use different functions and manipulate the algorithm to use it for a different type of vision system rather that human one.
I appreciate any ideas.
P.S. I should say that I asked Dr. Bruton himself whether is it possible to adapt his algorithm to different sensitivity curves and he told me it is possible if I have new functions for the other sensitivity curves, but still the question is about how to make the linear approximation.
I am studying the colour polymorphism of a crab spider and I want to know if birds can discriminate among the spider's colour morphs. I have calculated the excitation values of the four bird cone photoreceptors and transformed these into tetrahedral space coordinates (x, y, and z). I would like to represent these graphically in a colour tetrahedron, but i haven't been able to figure out how to obtain the coordinates for the vertices (representing the four classes of receptors: u/v, s, m, and l) of the tetrahedron. Any help will be much appreciated.
Presumably there are, but where are they located?
Many studies are addressed either to the visual stimuli (i.e. the overall attraction to colors or the spectral sensitivities of the photoreceptors) or to the olfactorial stimuli (attraction to chemical cues) however, for diurnal insects, when both systems may be stimulated simultaneously, what may be the outcome?
In other words, would an insect that in general is attracted to yellow, still prefer that even when exposed to food- or host- odors?
I am doing some spectrophotometry on nocturnal salamanders which gives me full spectral reflectance from about 300-800nm. However, I doubt this is all relevant to a nocturnal system so I want to filter the results to only include wavelengths of light present in the system. How would I best measure the wavelengths present in ambient light in the field?
Any test model I can use and reference?
Colour photoreceptor cells are found as double, triple or even quadruple cones in the retina of some birds, fish, amphibians and reptiles. I would love to have a clearer idea as to the purpose/advantage that this may have.
Correction of cataracts in relation to the true colors - color recognition.
It makes sense to determine the excitation purity of pulp.