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Research on Color Contrast #10

Open rachaelbradley opened 1 year ago

rachaelbradley commented 1 year ago

This issue is to gather research on color contrast. If you have links to color contrast research or are aware of individuals working in this space, please note that here.

Peer reviewed research studies on readability by people with disabilities are particularly valuable.

Please keep this issue clear of discussion and debate. It is meant to collect resources.

rachaelbradley commented 1 year ago

Research list for APCA: https://git.myndex.com/

Myndex commented 1 year ago

Specific to APCA:

APCA Easy Intro

APCA linktree

APCA Reviewed

APCA on GitHub

CLICK TO OPEN Links to APCA Related Repositories ### [Myndex/SAPC-APCA](https://github.com/Myndex/SAPC-APCA) The Main Documentation Repository, also reachable as a [webpage at git.apcacontrast.com](https://git.apcacontrast.com) ### [Myndex/apca-w3](https://github.com/Myndex/apca-w3) The Code Repository for code and basic algorithms for use in practical guidelines. See also [apcacontrast.com](https://apcacontrast.com) ### [Myndex/bridge-pca](https://github.com/Myndex/bridge-pca) The WCAG 2 backwards compatible bridge version. See also [BridgePCA.com](https://bridgepca.com/) ### [Myndex/deltaphistar](https://github.com/Myndex/deltaphistar) Delta-Phi-Star is a simplified general purpose algorithm, that modifies ∆L\* (delta-L-star) into a perceptual contrast for higher-spatial elements on displays. See also the [seestars repository](https://github.com/Myndex/seestars). ### [Myndex/max-contrast](https://github.com/Myndex/max-contrast) Max-Contrast is a simple algorithm that automatically flips a text color between black or white, based on the background color, compatible with APCA. ### [A11yReadTech](https://github.com/A11yReadTech) Inclusive Reading Technologies, the non-profit organization supporting research and development of readability technologies and [related guidelines](https://readtech.org/ARC/). ### [Myndex/Illuminated](https://github.com/Myndex/Illuminated) A repo collecting open public research notes and comments Myndex made regarding typography, CSS, color, contrast, and vision. ### [Myndex/colorparsley](https://github.com/Myndex/colorparsley) A lightweight but versatile mini-lib to parse color strings, objects, or numbers, developed for use with APCA-W3. ### [Myndex/font-x-size](https://github.com/Myndex/font-x-size) Under development, polyfill for setting font size based on x-height. -----

Generally Related to contrast, reading, and impairments:

CLICK TO OPEN Short Current Bibliography ### [Reading with low vision:](https://doi.org/10.1111/j.1444-0938.2010.00565.x) The impact of research on clinical management (2011) Jan Lovie--Kitchin PhD School of Optometry Queensland University of Technology  [doi.org/10.1111/j.1444-0938.2010.00565.x](https://doi.org/10.1111/j.1444-0938.2010.00565.x) --- ### [Luminance Contrast](https://colorusage.arc.nasa.gov/luminance_cont.php) Using Color In Information Display Graphics Larry Arend, with contributions from Alex Logan and Galina Havin NASA Website, NASA Ames Research Center, Human Systems Integration Division https://colorusage.arc.nasa.gov/luminance_cont.php --- ### [Human factors design standard (HFDS) (2003)](http://hf.tc.faa.gov/hfds) Federal Aviation Administration (FAA) HF-STD-001. Available for download at http://hf.tc.faa.gov/hfds --- ### An Engineering Model for Color Differences as a Function of Size M.Stone, D.Szafir, and V.Setlur Tableau Software, 2014 CIC_48_Stone_v3 --- ### Comparing the Shape of Contrast Sensitivity Functions for Normal and Low Vision S.Chung and G.Legge Vis Sci. 2016 Jan; 57(1): 198--207. doi: 10.1167/iovs.15-18084 PMCID: PMC4727522 --- ### Psychophysics of Reading (I, II, V, VI, XV, XVIII, XX) G.Legge, D.Pelli, G.Rubin et alia Vision Research, Vol. 25, No. 2, pp. 23-9252, 1985. Vision Research, Vol. 27, No. 7, pp. 1165-1177, 1987 Vision Research, Vol. 29, No. 1, pp. 79-91, 1989 Investigative Ophthalmology and Visual Science,, Vol. 37, No. 8, pp. 1492-1501, 1996. Vision Research, Vol. 38, No. 19, pp. 2949-2962, 1998. Vision Research, Vol. 41, pp. 725-743, 2001. --- ### Color Appearance Models M.D. Fairchild John Wiley and Sons, 3rd edition, 2013 --- ### [Realities and Myths of Contrast and Color](https://www.smashingmagazine.com/2022/09/realities-myths-contrast-color/) A.M.Somers [Realities and Myths of Contrast and Color • Smashing Magazine Sept. 2022](https://www.smashingmagazine.com/2022/09/realities-myths-contrast-color/) --- ### Colorimetry: Understanding the CIE System Janos Schanda, CIE  John Wiley & Sons, Inc. 2007 --- ### Does print size matter for reading? A review of findings from vision science and typography G.Legge, C.Bigelow Journal of Vision (2011) 11(5):8, 1--22 --- ### Model for the spatial contrast sensitivity of the eye P. Barten SPIE Optical Engineering Press 1999 --- ### [Computerized simulation of color appearance for dichromats](https://opg.optica.org/josaa/abstract.cfm?uri=josaa-14-10-2647#articleBody) H.Brettel, F.Viénot, J.Mollon 0740-3232/97/1002647-09 1997 Optical Society of America [Simulation of dichromat color](https://opg.optica.org/josaa/abstract.cfm?uri=josaa-14-10-2647#articleBody) -----

Interactive or Demonstrative

Accurate Colorblind Sim

APCA Demonstrator

Tools and Applications

Myndex commented 1 year ago

Color and Contrast Outcomes

This had been posted in the old Silver repo, adding it here as it directly relates.

Color, as in hue and colorfulness, is distinctly separate from luminance, which is "colorless" spectrally weighted light.

It's convenient to think of luminance as a black & white TV set, and to think of color as just the small amount that's added to that black-and-white signal. Because that's literally how the human vision system processes it as well, and the separate components of luminance and color serve different purposes in our neurology.

NOTE: The fact that contrast sensitivity is dictated by spatial frequency is a matter of peer-reviewed scientific consensus dating back to the 1960s. ⁵

Click for additional background _**Luminance**_ carries the **high** spatial frequency information such as text, and color (hue) exists in the very **lowest** spatial frequencies. _"...reading speed depends on the spatial frequency and contrast of the text. When text contrast is low, reading speed shows strong spatial-frequency dependence..."_ ⁴ Visual presentation properties such as line spacing affect spatial frequency and therefore directly affect contrast and readability. Currently they are in a different area, but they belong as part of the overall visual contrast/visual hierarchy group. DataViz and nontext are often at low spatial frequencies, and use of color for data coding is related closely to DataViz, but _not particularly related_ to visual contrast for readability. Meanwhile, reading _requires good luminance contrast_, without regard to color as in hue. _(An exception is rejecting pure red paired with black or dark colors, note that APCA essentially does this naturally anyway, as read on black is actually bad for standard vision as well)._

Some of the other adds:

Text zoom, Text use-cases, non-text use-cases, text in an SVG, contrast for images of text/logos.

Click for additional background These were some editorial adds made to the Google doc along with comments. I did not delete any lines from the other areas such as visual presentation, but I did leave comment notes at those in the document. - Text zoom, as text size is a primary factor in visual contrast because of the spatial frequency characteristic of text size, the ability to zoom text and the nature thereof is important. - **Text use-cases** and **non-text use-cases**, as it provides the structure for which elements must have high contrast and which elements can have relaxed contrast which is required for practical design implementation.⁶ - And while images of text does partly belong over with alt text, it **_also_** belongs in visual contrast, as images with text or semantic imagery that is required for understanding content. Also added a line for "text in an SVG" and formatted rich-text for alt text in conjunction with images/SVGs of formatted text or logos.

For convenience, here are the tables relating to color and visual contrast from the Google doc as split / combined into these two guidelines:

Guideline: Content does not rely on color alone to convey meaning, uses sufficient contrast.

2.x SC Short Description
1.4.1 Use of Color (hue and colorfulness)
1.4.1a Use of color in controls
1.4.1b Use of color in organizing content
1.4.11 Non-text Contrast - UI Components
1.4.11a Non-text Contrast - Graphics
1.4.11b Non-text Contrast - Dataviz
1.4.11c Non-text use-cases: Semantic, Symbolic, DataViz, Container.⁶

Scope: Item or View

Expertise Needed:

Guideline: Visually readable content uses ample luminance contrast.

2.x SC Short Description
1.4.3 Contrast (Minimum)
1.4.3a Contrast exceptions (see use-cases)
1.4.4 Content Zoom
1.4.4a Proportional Text Zoom
1.4.6 Contrast (Enhanced)
1.4.6a Font weight and glyph characteristics
1.4.6b Text use cases: Fluent Body Text, fluent, sub-fluent, spot-read, ancillary.⁶
1.4.8 Use of contrast in the visual hierarchy (was Visual Presentation)
1.4.8a User selectable text and background colors for blocks of text.
1.4.8b Column width for body-text rules.⁷
1.4.8c Body-text justification rules.⁸
1.4.8d Body-text line spacing (leading) & paragraphs.⁹
1.4.8e Sufficient margins and padding around text
1.4.5 Images of Text, when the text is part of content it meets contrast minimums.
1.4.5a SVGs containing text, rich-text formatted alt-text (logos).

Scope: Item or View

Expertise Needed:

Thank you for reading.

A general reference for a crash-course in color and contrast: The Realities And Myths Of Contrast And Color

Footnotes 1) G.Legge, et alia (Psychophysics of Reading) 2) M.Stone (NIST,Guidelines for Using Color...) 3) L.Arends (NASA,Individual Differences in Color Vision) 4) S. Chung,B.Tjan Spatial-frequency and contrast properties of reading 5) Stevens, 1961; Bartleson and Breneman 1967

6) Click for refs & discussion of text use cases ### Text Use Cases * **FLUENT** *(primary content)* * **High-Fluent Readability** *(Block/Body Text)* * **Defined as:** a block or column of *more than two* continuous lines of content text that uses a readable font with an **x-height** of \~16px or *less ( < 32px)* . * \*\*Fluent Readability (\*\**Primary* content that is *not* body text) * **Defined as:** *up to* two and a half lines of continuous text. * **Large Fluent header/title content** * **Defined as:** fluent subcategory of "large content" such as big, bold headlines, and generally referring to text larger than \~32px. * **SUB FLUENT** *(secondary content)* * Soft Readability, small sub-fluent secondary/ancillary content * **Defined as:** non-primary content with *relaxed* readability needs. * **Spot Readability,** *(sub-fluent* ***"non-content"****)* * **Defined as:** non-content text of an incidental nature. * **Logo or Branding,** **brand related logo, symbol, service mark.** * This category relates to specific colors that are required as part of a brand or logotype. * **Incidental Text in Images** incidental means text in images not critical to the understanding, nor specifically contributing to the content, in other words a photo of a city street, and you can see the text on the signs for the various stores. ### NON Text Use Cases Regarding nontext use cases, one set is: - Intrinsically semantic (icon or pictogram, land map) - Contextually semantic (chart lines, pie chart pieces, demographics map, lat/long lines, legend codes) - Meta semantic (focus or state, dynamic driving map, animatable potentially in combination with 1 & 2) - Discernible non-semantic (border, abstract button shape, map outer edge or legend area, zoom-up enlargement areas) So another idea for non-text use cases is: Semantic, Symbolic, DataViz, Container SEE: Draft [Use Cases, Conformance, Research, and Glossary](https://github.com/Myndex/SAPC-APCA/discussions/39)
7) Click for refs & discussion of characters per line "80 characters per line" is a somewhat unsupported value pulled out of thin air. The history of 80 characters has much to do about the economics of IBM's equipment back in the day, than it has to do with any actual readability research. In other words, asserting lines should be 80 is pseudoscience. Lines of code can reasonably be much longer and there's a number of arguable reasons to not have line breaks in code. But 80 characters is usually too much for columns of body text, which should be much shorter, and this varies per language and writing system. **_"...The 66-character line (counting both letters and spaces) is widely regarded as ideal...."_** -R.Bringhurst from the authoritative _"The Elements of Typographic Style"_ ### _It could be non-normative and informative._ the best practices recommendation for columns to have an average line length of 50 to 70 characters (for latin-based). Other languages need an expert typographer in that specific language to work on certain international outcomes.
8) Click for discussion of body-text justification ### For web content, columns of body-text must be: - left justified for ltr reading languages, (meaning aligned to the left) and - right justified for rtl reading languages, - **Never** full-justified, meaning full lines aligned to both the left and right margins, and - **Never** center justified—Center justified body-text is actually harder to read them full-justified. It's important recognize that full-justification requires the judgment of the eye of a skilled typographer in order to make it work. Web content is responsive and interactive and changes position. Like all automatic adjustment systems it does not benefit from human intervention, and the automated systems for things like text reflow in a browser are not nearly at the level they would need to be to accomplish appropriately set full justification. That said, central justification of body text is even worse for reading, because the beginning of each line is that a different place that makes it very difficult for the eye to scan back to the beginning of the next line. And also, all of this is for body text. These rules do not and should not apply to two or three lines of much larger headline text as an example. On that note, **_the use case for body text is very different from the use case for any other form of text on a page._**
9) Click for refs & discussion of line-height This is from another unsupported SC which originally says something like "must be 1.5 times the line height". This is **practically meaningless in CSS**, because what's important is the distance between glyphs, and for Latin alphabet for instance, that's going to be between lowercase Lines, and the x-height ratio to font-size is vastly different depending on the font family, by as much as ±50% or more. ### _It could be non-normative and informative._ While I revised it for now to be 2.5 times the x-height, i.e. `p{line-height:2.5ex}`, even that is not the whole story. Whether or not increasing line height to a certain degree is helpful is not a matter of scientific consensus, and there are enough variables involved that it's not so cut and dry, and I certainly dependent on the font design font weight and overall size and number of characters per line on average and so forth. This goes for paragraph spacing as well, is there a number of ways to indicate paragraphs including indenting out outdenting, and it is out of scope for a law to say that you must use paragraph spacing as opposed to indenting as an example. These arbitrary values are really notwithstanding, as the reality is much more nuanced. Nevertheless, it is well known though is that the spatial frequency and the effects of crowding are very important readability, but you can't make a blanket statement on how much letter or line spacing needs to be added, as that is a function of every individual font design and **every individual font design is going to need something different.** ### Blanket arbitrary values do not work here Especially not in a guideline that is intended to become law at some point. _Some related references:_ D.Pelli et alia [Crowding and eccentricity determine reading rate](https://pubmed.ncbi.nlm.nih.gov/18217835/) S.Chung et alia [Reading speed does not benefit from increased line spacing in AMD patients](https://pubmed.ncbi.nlm.nih.gov/18772718/) A.Calabrèse et alia [Small effect of interline spacing on maximal reading speed in low-vision patients...](https://pubmed.ncbi.nlm.nih.gov/19834038/)
  1. Language experts are needed as guidelines designed for Latin alphabet are likely not appropriate for many other writing systems.
Myndex commented 1 year ago

Partial Bibliography

The following references are selected early work product from A.Somers 2019/2020 research into visual contrast and accessibility. The 2021/2022 to come.

Organized into clickable sections to keep it more manageable.

CLICK FOR Key References   ### Key References ------ **Brightness function: Effects of adaptation** J. C. Stevens and S. S. Stevens J. Opt. Soc. Am., vol. 53, pp. 375-385, 1963 ------ **Brightness Perception in Complex Fields** C. J. Bartleson and E. J. Breneman J. Opt. Soc. Am., vol. 57, pp. 953-957, 1967 ------ **A Technical Introduction to Digital Video** C. A. Poynton John Wiley & Sons, New York, 1996 ------ **Gamma and its disguises: The nonlinear mappings of intensity in perception, CRTs, film and video** C. A. Poynton J. SMPTE, pp. 1099-1108, 1993 ------ **Color Appearance Models** M.D. Fairchild John Wiley and Sons, 3 edition, 2013. ------ **In color perception, size matters** Maureen Stone IEEE Computer Graphics and Applications, 32(2):8–13, March/April 2012. ------ **An engineering model for color difference as a function of size** Maureen Stone, Danielle Albers Szafir, and Vidya Setlur In 22nd Color and Imaging Conference. Society for Imaging Science and Technology, 2014. ------ **Adaptive luminance contrast for enhancing reading performance and visual comfort on smartphone displays** Nooree Na and Hyeon-Jeong Suk Optical Engineering 53(11), 113102 (November 2014) ------ **The CIE DE2000 Color-Difference Formula: Implementation Notes, Supplementary Test Data, and Mathematical Observations** Gaurav Sharma,1\* Wencheng Wu,2 Edul N. Dalal2 COLOR research and application Volume 30, Number 1, February 2005 ------ **Effects of chromatic and luminance contrast on reading.** Knoblauch K1, Arditi A, Szlyk J. J. Opt. Soc. Am. A/Vol. 8,No. 2/February 1991 ------ **Psychophysics of reading. XI. Comparing color contrast and luminance contrast.** Legge GE1, Parish DH, Luebker A, Wurm LH. Minnesota Laboratory for Low-Vision Research, University of Minnesota, Minneapolis 55455. ------ **Colour and luminance contrasts predict the human detection of natural stimuli in complex visual environments** Thomas E. White 1, Bibiana Rojas 2, Johanna Mappes 2, Petri Rautiala 3 and Darrell J. Kemp 1 Biol. Lett. 13: 20170375. [http://dx.doi.org/10.1098/rsbl.2017.0375](http://dx.doi.org/10.1098/rsbl.2017.0375)<>
CLICK FOR Neurological / Visual Cortex   ### Neurological / Visual Cortex ------ **The Empirical Characteristics Of Human Pattern Vision Defy Theoretically-Driven Expectations** Peter NeriID PLOS Computational Biology December 4, 2018 [https://doi.org/10.1371/journal.pcbi.1006585](https://doi.org/10.1371/journal.pcbi.1006585) ------ **Chromatic And Luminance Losses With Multiple Sclerosis And Optic Neuritis Measured Using Dynamic Random Luminance Contrast Noise.** Flanagan P1, Zele AJ. Department of Psychology, Deakin University, Victoria 3217, Australia. flanagan@deakin.edu.au ------ **First- and second-order contrast sensitivity functions reveal disrupted visual processing following mild traumatic brain injury** Daniel P.Spiegela Alexandre Reynaud Tatiana Ruiz Maude Laguë-Beauvaisac Robert Hess Reza Farivara Vision Research 122 (2016) 43–50 ------ **Representation of Surface Luminance and Contrast in Primary Visual Cortex** Ji Dai1,2 and Yi Wang1 Cerebral Cortex April 2012;22:776-787 doi:10.1093/cercor/bhr133
CLICK FOR Monitor Technology Related   ### Monitor Technology Related ------ **Human factors design standard (HFDS)** Federal Aviation Administration (FAA). (2003) HF-STD-001. Available for download at [http://hf.tc.faa.gov/hfds](http://hf.tc.faa.gov/hfds) ------ **Using Color In Information Display Graphics** Larry Arend, with contributions from Alex Logan and Galina Havin NASA Website, NASA Ames Research Center, Human Systems Integration Division [http://colorusage.arc.nasa.gov](http://colorusage.arc.nasa.gov) ------ **Color Usability On Air Traffic Control Displays** Ulf Ahlstrom, FAA and Larry Arend NASA Ames Research Center Proceedings Of The Human Factors And Ergonomics Society 49Th Annual Meeting—2005 93 ------ **Perceptual Display Calibration** Rafa􏱈l K. Mantiuk Displays: Fundamentals & Applications, Second Edition by Rolf R. Hainich and Oliver Bimber, A K Peters/CRC Press 2016. ------ **Electronically / Optically Generated Airborne Displays** Department Of Defense Handbook MIL-HDBK-87213A ------ **A Multiscale Model of Adaptation and Spatial Vision for Realistic Image Display** Sumanta N. Pattanaik James A. Ferwerda Mark D. Fairchild Donald P. Greenberg Program of Computer Graphics†, Cornell University
CLICK FOR Psychophysics   ### Psychophysics ------ **“Symmetry and constancy in the perception of negative and positive luminance contrast”** D. A. Burkhardt, J. Gottesman, D. Kersten, G. E. Legge, JOSA A, 1(3), 309-316 (1984). ------ **Psychophysics Of Reading II. Low Vision** Gordon E. Legge, Gary S. Rubin, Denis G. Pelli, And Mary M. Schleske ------ **Color Improves Object Recognition in Normal and Low Vision** Gordon E Legge Article in Journal of Experimental Psychology Human Perception & Performance [September 1993 DOI: 10.1037/0096-1523.19.4.899 · Source: PubMed](September%201993%20DOI:%2010.1037/0096-1523.19.4.899%20·%20Source:%20PubMed) ------ **Perceived image contrast and observer preference I. The effects of lightness, chroma, and sharpness manipulations on contrast perception** Anthony J. Calabria and Mark D. Fairchild Munsell Color Science Laboratory—Rochester Institute of Technology ------ **Spatial-Frequency And Contrast Properties Of Reading In Central And Peripheral Vision** Chung ST, Tjan BS J Vis. 2009;9(9):1–19. Published 2009 Aug 28. doi:10.1167/9.9.16 ------ **Edge-Aware Color Appearance** Kim, M. H., Ritschel, T., and Kautz, J. 2011 ACM Trans. Graph. 30, 2, Article 13 (April 2011), 9 pages. DOI = 10.1145/1944846.1944853 [http://doi.acm.org/10.1145/1944846.1944853](http://doi.acm.org/10.1145/1944846.1944853) ------ **Perceived contrast in complex images** Haun, A. M., & Peli, E. (2013) Journal of Vision, 13(13):3, 1–21, doi:10.1167/13.13.3 [http://www.journalofvision.org/content/13/13/3](http://www.journalofvision.org/content/13/13/3) ------ **Tone Mapping Algorithm for Luminance Separated HDR Rendering Based on Visual Brightness Functions** Hyuk-Ju Kwon, Sung-Hak Lee†, Seok-Min Chae†, and Kyu-Ik Sohng † National Research Foundation of Korea [(NRF) funded by the Ministry of Education, Science and Technology (2011-0025905).]((NRF)%20funded%20by%20the%20Ministry%20of%20Education,%20Science%20and%20Technology%20(2011-0025905).) ------ **Viewing distance requires large characters to ensure legibility on TV-set.** Cédric Bertolus, Daniel Bailleul, Marc Mersiol. AFIHM. 29ème conférence francophone sur l’Interaction Homme- Machine, Aug 2017, Poitiers, France. ACM, IHM-2017, 10 p., 2017, [http://ihm2017.afihm.org](http://ihm2017.afihm.org) 10.1145/3132129.3132133. hal-01578483 ------ **The effect of font and line width on reading speed in people with mild to moderate vision loss** Gary S. Rubin, Mary Feely, Sylvie Perera, Katherin Ekstrom and Elizabeth Williamson Ophthal. Physiol. Opt. 2006 26: 545–554 ------ **The Effects of Font Type and Spacing of Text for Online Readability and Performance** Nafiseh Hojjati & Balakrishnan Muniandy Universiti Sains Malaysia Contemporary Educational Technology, 2014, 5(2), 161-174 ------ **Recognition versus Resolution: a Comparison of Visual Acuity Results Using Two Alternative Test Chart Optotype** Jonathan S. Pointer J Optom 2008;1:65-70 ------ **Luminance contrast sensitivity for achromatic and chromatic parafoveal stimuli under mesopic conditions (Mesopic visual function in healthy and Aged-related Macular Degeneration (AMD) subjects: relating structure to function)** João Lourenço Stephanie Mroczkowska Paul H Artes Luis Garcia-Suarez British Congress of Optometry and Visual Science 2019 (BCOVS 2019) [DOI: 10.13140/RG.2.2.15959.83367](DOI:%2010.13140/RG.2.2.15959.83367) ------ **Spatial Contrast Sensitivity Vision Loss in Children with Cortical Visual Impairment** William V. Good,1 Chuan Hou,1 and Anthony M. Norcia1 Investigative Ophthalmology & Visual Science, November 2012, Vol. 53, No. 12 ------ **Spatial-frequency bandwidth of perceived contrast** Kaisa Tiippana a,\*, Risto Na ̈sa ̈nen b Vision Research 39 (1999) 3399–3403 [www.elsevier.com/locate/visres](www.elsevier.com/locate/visres) ------ **Psychophysics Of Reading: XI. Comparing Color Contrast And Luminance Contrast ** Gordon E. Legge, David H. Parish, Andrew Luebker And Lee H. Wurm
CLICK FOR Clinical And Experimental   ### Clinical And Experimental ------ **Reading in low vision** Cheong, Lovie-Kitchin and Bowers OPTOMETRY ------ **Determining magnification for reading with low vision** Allen MY Cheong BSc (Optom) Jan E Lovie-Kitchin PhD MSc Alex R Bowers PhD OPTOMETRY ------ **Effect of room illuminance on monitor black level luminance and monitor calibration.** AMAChakrabarti K, Kaczmarek RV, Thomas JA, Romanyukha A. J Digit Imaging. 2003;16(4):350–355. doi:10.1007/s10278-003-1720-5 ------ **Rethinking ADA signage standards for low-vision accessibility** Arditi A. J Vis. 2017;17(5):8. doi:10.1167/17.5.8 ------ **Spatial-frequency and contrast properties of reading in central and peripheral vision** Chung ST, Tjan BS J Vis. 2009;9(9):1–19. Published 2009 Aug 28. doi:10.1167/9.9.16 ------ **Human Computer Interaction: Legibility and Contrast** Silvia Zuffia, Carla Brambillab, Giordano Berettac, Paolo Scalaa 14th International Conference on Image Analysis and Processing (ICIAP 2007) ------ **Letter case and text legibility in normal and low vision** Aries Arditi, Jianna Cho Vision Research 47 (2007) 2499–2505 ------ **Psychophysical contrast calibration** Long To, Russell L. Woods, Robert B. Goldstein, Eli Peli Vision Research 90 (2013) 15–24 ------ **Guidelines for Using Color in Voting Systems** Maureen Stone, Sharon J. Laskowski NIST—Information Access Division Information Technology Laboratory National Institute of Standards and Technology NISTIR 7537 ------ **Contrast sensitivity of the human eye and its effects on image quality** Barten, P. G. J. (1999) Eindhoven: Technische Universiteit Eindhoven DOI: 10.6100/IR523072 ------ **Positive and negative polarity contrast sensitivity measuring app** Alex D. Hwang and Eli Peli IS&T Int Symp Electron Imaging. 2016 ------ **Visual Calibration and Correction for Ambient Illumination** KATE DEVLIN and ALAN CHALMERS University of Bristol and ERIK REINHARD ACM Transactions on Applied Perception, Vol. 3, No. 4, October 2006.
CLICK FOR Color Vision Related Resources   ### Color Vision Related Resources ------ **A Clinically Accurate [Color Blind Simulator**](https://www.myndex.com/CVD/) using the peer reviewed Brettel/Viénot Model. This is a simulator of Color Vision Deficiency (CVD, sometimes inaccurately called "colorblind"). It allows processing your screenshot and shows multiple types of CVD at once. Site includes a biblipgraphy and additional discussion and explaination. ------ **Spectral Sensitivity of Color-Blind Observers and the Cone Photopigments** V Smith, J Pokorny (1972) Vision Res. Vol. 12, pp. 2059-2071. PergamonPress 1972. Printed in Great Britain. ------ **Response Functions for Types of Vision According to the Muller Theory** Deane B. Judd (1949) Part of Journal of Research of the National Bureau of Standards, Volume 42, January 1949
CLICK FOR Interesting Concepts in Improving Accessibility   ### Interesting Concepts in Improving Accessibility ------ **Accessibility for Individuals with Color Vision Deficiency** David R. Flatla (2011) Doctoral Symposium UIST’11, October 16–19, 2011, Santa Barbara, CA, US [hci.usask.ca/uploads/237-UIST-DC.pdf](http://hci.usask.ca/uploads/237-UIST-DC.pdf) ------ **Improving Discrimination in Color Vision Deficiency by Image Re-Coloring** Huei-Yung Lin, Li-Qi Chen, & Min-Liang Wang (2019) Sensors (Basel). 2019 May; 19(10): 2250. [www.ncbi.nlm.nih.gov/pmc/articles/PMC6567888/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6567888/) ------ **Enhancing Color Representation for the Color Vision Impaired** Jia-Bin Huang, Sih-Ying Wu, and Chu-Song Chen (??) SemanticScholar.org [pdfs.semanticscholar.org/a928/736...pdf](https://pdfs.semanticscholar.org/a928/7362636fda805aefa7dad81e763ff8a3c450.pdf) ------ **Increasing Accessibility for Map Readers with Acquired and Inherited Color Vision Deficiencies: A Re-Coloring Algorithm for Maps** Gretchen M. Culp (2016) CUNY Academic Works. [https://academicworks.cuny.edu/gc_etds/1243/](https://academicworks.cuny.edu/gc_etds/1243/?utm_source=academicworks.cuny.edu%2Fgc_etds%2F1243&utm_medium=PDF&utm_campaign=PDFCoverPages) ------ **Information Preserving Color Transformation for Protanopia and Deuteranopia** Huang, Tseng, Wu, Wang (2007) October 2007 IEEE Signal Processing Letters 14(10):711 - 714 DOI: 10.1109/LSP.2007.898333 [www.researchgate.net/publication/3343749_Information...Deuteranopia](https://www.researchgate.net/publication/3343749_Information_Preserving_Color_Transformation_for_Protanopia_and_Deuteranopia) ------ **Contour Enhancement Algorithm for Improving Visual Perception of Deutan and Protan Dichromats** M. Madalena, G. Ribeiro, Abel J.P. Gomes (2019) International Journal of Interactive Multimedia and Artificial Intelligence, Vol. 5, No 5 [www.ijimai.org/journal/...53220.pdf](https://www.ijimai.org/journal/sites/default/files/files/2019/05/ijimai_5_5_10_pdf_53220.pdf) ------
Myndex commented 1 year ago

Some key graphics

These graphics were developed to help explain some of the concepts involved in vision, contrast, and readability.

Visual Presentation

Visual Presentation-2.pdf

Contrast Sensitivity Curve

This is the human contrast sensitivity curve. The grey sample fonts are all at the exact same color of #c7c7c7, they become impossible to read as they get thinner. New contrast sensitivity Graph 5

CVD aka colorblind

This shows standard vision upper left and then different forms of color insensitive to demonstrate the colors that they can see and not see.

CVD color wheels small, this shows standard vision upper left and then different kinds of color blind to demonstrate the colors that they can see and not see

Dark Mode Comparison

This comparison shows WCAG2 text on the left and APCA on the right, with minimums in dark mode, only the APCA text is easily readable.

DarkModeComparev2_2022 this comparison shows WCAG2 text on the left and APCA on the right in dark mode, only the APCA text is easily readable

Font-Smoothing can be bad

in this graphic a thin font is shown with WebKit font smoothing antialiased or in auto, an anti-aliased, much of the font is subsumed into the background making the font thinner in weight and therefore lower in contrast. In auto the contrast is improved because the weight is not damaged as much, and it is still smooth because default anti-aliasing is more than sufficient for small fonts.
Font Smoothing Comparison - in this graphic a thin font is shown with WebKit font smoothing antialiased or in auto, an anti-aliased, much of the font is subsumed into the background making the font thinner in weight and therefore lower in contrast. In auto the contrast is improved because the weight is not damaged as much, and it is still smooth because default anti-aliasing is more than sufficient for small fonts

Font-size is inconsistent

This graphic shows the font Verdana at 14px and the font Times New Roman also at 14px, showing that even though they are both set to the same exact font size, Times new Roman is substantially smaller as rendered to the screen. font Size Comparison - this graphic shows the font Verdana at 14px and the font Times New Roman also at 14px, showing that even though they are both set to the same exact font size, Times new Roman is substantially smaller as rendered to the screen

Screen Pitch at CSS Ref px

This chart indicates the screen pitch for the CSS canonical measurement px to equal 1.278 arc minutes.

ScreenPPItoDistance this chart indicates the screen pitch for the CSS canonical measurement px to equal 1.278 arc minutes

WCAG to APCA

This shows the functional similarity between WCAG2 contrast values and APCA Lc values, measured near center contrast.

WCAG to APCA comparison table Functional

Critical Font Size Table

This is a table that indicates the critical font size for best readability at different levels of visual acuity. Critical Font Size 2021 this is a table that indicates the critical font size for best readability at different levels of visual acuity

Critical Print Size

This graph from research of Lovi-kitchin shows the contrast reserve and critical contrast.

Critical Print Size this graph from research of Lovi-kitchin shows the contrast reserve and critical contrast
ericwbailey commented 6 months ago

Thank you for highlighting and centering the disabled perspective with this issue—it is really appreciated.

I've been doing some research on the academic end of things, and am in the process of performing outreach to individuals whose domain expertise may be applicable for this concern.

I am posting this to communicate that work is occurring here, with the hope that it keeps this issue open until I can either make introductions or come back with no interest expressed from the people I am reaching out to.

Part of this is the translation layer, where these individuals may not be aware of/participate in GitHub or WCAG. I am hoping my outreach communication helps with this aspect.