|
|
| Line 1: |
Line 1: |
| In [[colorimetry]] the '''OSA-UCS''' (Optical Society of America Uniform Color Space) is a [[color space]] first published in 1947 and developed by the [[Optical Society of America]]’s Committee on Uniform Color Scales.<ref name="BabelColor">{{cite web |url=http://www.babelcolor.com/download/AN-7%20The%20OSA%20UCS.pdf |title=BabelColor: The Optical Society of America Uniform Color Scales}}</ref> Previously created color order systems, such as the [[Munsell color system]], failed to represent perceptual uniformity in all directions. The committee decided that, in order to accurately represent uniform color differences in each direction, a new shape of three dimensional [[cartesian geometry]] would need to be used.<ref name=BabelColor/><ref name="Kuehni">{{cite book |last1=Kuehni |first1=Rolf G. |title=Color, An Introduction to Practice and Priciples, 3rd Edition |publisher=[[John Wiley & Sons|Wiley]] |pages=100–105 |ISBN=978-1-118-17384-8}}</ref>
| | CMS provides the best platform to create websites that fulfill all the specifications of SEO. Medical word press themes give you the latest medical designs. I thought about what would happen by placing a text widget in the sidebar beneath my banner ad, and so it went. If you are using videos on your site then this is the plugin to use. It's as simple as hiring a Wordpress plugin developer or learning how to create what is needed. <br><br>Thus, it is imperative that you must Hire Word - Press Developers who have the expertise and proficiency in delivering theme integration and customization services. If a newbie missed a certain part of the video then they could always rewind. A Wordpress plugin is a software that you can install into your Wordpress site. You can up your site's rank with the search engines by simply taking a bit of time with your site. If you cherished this article and you would like to be given more info regarding [http://247url.info/wordpress_backup_plugin_859923 wordpress backup plugin] nicely visit the web site. That's a total of 180$ for each Wordpress theme if you sell 3 links and keep the designer link for your own website, or 240$ if you sell all links. <br><br>But before choosing any one of these, let's compare between the two. To sum up, ensure that the tactics are aiming to increase the ranking and attracting the maximum intended traffic in the major search engines. We can active Akismet from wp-admin > Plugins > Installed Plugins. Every single Theme might be unique, providing several alternatives for webpage owners to reap the benefits of in an effort to instantaneously adjust their web page appear. If you have any questions on starting a Word - Press food blog or any blog for that matter, please post them below and I will try to answer them. <br><br>Digg Digg Social Sharing - This plugin that is accountable for the floating social icon located at the left aspect corner of just about every submit. Quttera - Quttera describes itself as a 'Saa - S [Software as a Service] web-malware monitoring and alerting solution for websites of any size and complexity. A higher percentage of women are marrying at older ages,many are delaying childbearing until their careers are established, the divorce rate is high and many couples remarry and desire their own children. The most important plugins you will need are All-in-One SEO Pack, some social bookmarking plugin, a Feedburner plugin and an RSS sign up button. Where from they are coming, which types of posts are getting top traffic and many more. <br><br>Yet, overall, less than 1% of websites presently have mobile versions of their websites. Sanjeev Chuadhary is an expert writer who shares his knowledge about web development through their published articles and other resource. Offshore Wordpress development services from a legitimate source caters dedicated and professional services assistance with very simplified yet technically effective development and designing techniques from experienced professional Wordpress developer India. This is because of the customization that works as a keystone for a SEO friendly blogging portal website. Likewise, professional publishers with a multi author and editor setup often find that Word - Press lack basic user and role management capabilities. |
| | |
| == History and Development ==
| |
| | |
| The development of the OSA-UCS took place during many years, from 1947-1977. Not long after the first mathematical color model was developed by the [[International Commission on Illumination|CIE]], [[David MacAdam]] showed that when selecting a color on the CIE [[Chromaticity|chromaticity diagram]], it could not be guaranteed that colors of the same perceived color difference around this color were at the same color distance with respect to the reference color.<ref name=BabelColor/> More simply, the Euclidean distance between any two colors on the chromaticity diagram could not be used as a uniform measure of perceived color difference. Immediately following this discovery work began to create a space that would behave uniformly in all directions of color difference.
| |
| | |
| Starting with a sample of 59 colored tiles of non-uniform color differences, the OSA asked 72 observers to judge color differences between the different sample tiles.<ref name=Kuehni/> From the data collected, formulas were developed and parameters were defined to create the new uniform color space. They chose the reference 10 degree observer and [[Illuminant D65]] to characterize the uniform space and a neutral gray background of 30% reflectance. In the end, 558 color samples were produced - 424 full step and 54 half step - and distributed by the OSA.<ref name=BabelColor/>
| |
| | |
| == Design ==
| |
| | |
| === Geometry ===
| |
| | |
| [[File:Cuboctahedron.svg|thumb|[[Cuboctahedron]].]]
| |
| | |
| The ideal color solid with points all at an equal distance from a center point is a sphere - however a collection of spheres can not be packed to form a larger solid without gaps. The geometry that the OSA finally chose is a [[rhombohedral lattice]] based on a [[cuboctahedron]]. Each of the 12 vertices of this solid are equal distance from the center, as well as from each of their neighbors. The last step to completing this geometry was in a rescaling of the vertical L axis, in order to achieve integer coordinate locations for color description. The color distance uniformity is maintained, as only the axis dimensions are scaled, and the scaling is accounted for in the color distance formula.<ref name=BabelColor/>
| |
| | |
| === Coordinate Values ===
| |
| | |
| The three perpendicular dimensions of the OSA-UCS are the [[Lightness (color)|lightness]] dimension '''L''', the [[Yellow|jaune]] dimension '''j''' (a yellow/blue [[Opponent process|opponent]] dimension) and the [[green]] dimension '''g''' (a green/red [[Opponent process|opponent]] dimension).
| |
| | |
| ==== Lightness (L) ====
| |
| | |
| The lightness scale of the OSA-UCS color solid varies vertically from about -10 to 8. UCS lightness of 0 corresponds to the 30% reflective neutral background gray selected for their samples, while lighter shades have positive values and darker shades have negative values.
| |
| | |
| ==== Jaune (j) ====
| |
| | |
| The jaune dimension of the OSA-UCS color solid runs horizontally and perpendicular to the '''L''' dimension. This is a yellow-blue chromatic dimension, varying from positive values appearing more yellowish to negative values appearing more blueish. A '''j''' value of 0 lies along the neutral axis.
| |
| | |
| ==== Green (g) ====
| |
| | |
| The green dimension of the OSA-UCS runs horizontally perpendicular to both the '''L''' and '''j''' dimensions. This green-red chromatic axis varies from more greenish positive values to more pinkish negative values. Again, a '''g''' value of 0 lies along the neutral (L) axis.
| |
| | |
| === Color Groupings ===
| |
| | |
| The cuboctahedron structure of the OSA-UCS color solid can be geometrically divided into 9 planes, known as [[cleavage planes]]. These 9 cleavage planes are defined as:<ref name="OSAUCS">{{cite web |url=http://www.handprint.com/HP/WCL/IMG/OSA/index.html |title=Optical Society of America Uniform Color Scales (OSA-UCS)}}</ref>
| |
| * '''L''' - A plane of constant L (lightness) that runs perpendicular to the L axis, where j and g can take on any values.
| |
| * '''j''' - A plane of constant j (yellow-blueness) that runs perpendicular to the j axis, where L and g can take on any values.
| |
| * '''g''' - A plane of constant g (red-greenness) that runs perpendicular to the g axis, where L and j can take on any values.
| |
| * '''L+j''' - A plane of constant L+j that runs parallel to the g axis, at 35° from the L axis and 55° from the j axis.
| |
| * '''L-j''' - A plane of constant L-j that runs parallel to the g axis, at 35° from the L axis and 55° from the j axis.
| |
| * '''L+g''' - A plane of constant L+g that runs parallel to the j axis, at 35° from the L axis and 55° from the g axis.
| |
| * '''L-g''' - A plane of constant L-g that runs parallel to the g axis, at 35° from the L axis and 55° from the g axis.
| |
| * '''j+g''' - A plane of constant j+g that runs parallel to the L axis, at 45° from the j and g axes.
| |
| * '''j-g''' - A plane of constant j-g that runs parallel to the L axis, at 45° from the j and g axes.
| |
| | |
| === Color Difference ===
| |
| | |
| OSA-UCS color difference is defined by the simple [[Euclidian distance]] between two colors in the color space, that takes into account the scaling done to the L axis. The formula used to calculate color difference between color 1 and 2 is:
| |
| | |
| :<math>\Delta UCS = \sqrt{(\sqrt{2}L_2 - \sqrt{2}L_1)^2 + (j_2 - j_1)^2 + (g_2 - g_1)^2} = \sqrt{2 \Delta L^2 + \Delta j^2 + \Delta g^2}</math>
| |
| | |
| Due to the design of the system, the color difference between two neighbors in the OSA-UCS color space is always 2. Small color differences can be accurately calculated using this formula. Larger color differences, however, require a non-linear correction for accuracy.<ref name=BabelColor/>
| |
| | |
| == Color Transformations ==
| |
| | |
| Although there is no direct conversion between OSA-UCS and [[CIEXYZ]], analytic conversion methods have been created and tested for accuracy.<ref>{{cite journal |last1=Kobayasi |first1=Mituo |last2=Yosiki |first2=Kayoko |title=Effective conversion algorithm from OSA-UCS to CIEXYZ |date=June 2002 |volume=4421 |issue=1 |journal=Proceedings of SPIE |doi=10.1117/12.464524}}</ref>
| |
| | |
| === CIEXYZ to OSA-UCS ===
| |
| | |
| To perform an analytical conversion from OSA-UCS to CIEXYZ, the following steps should be followed. First a factor representing the [[Helmholtz-Kohlrausch effect]] must be calculated from the x and y chromaticity coordinates:
| |
| | |
| :<math>K = 4.4934x^2 + 4.3034y^2 - 4.276xy - 1.3744x - 2.5643y +1.8103</math>
| |
| | |
| Next determine the modified luminous reflectance:
| |
| | |
| :<math>Y_0 = K*Y</math>
| |
| | |
| Then calculate the lightness and [[Colorfulness|chroma]] modification factor:
| |
| | |
| :<math>L = \frac{1}{\sqrt{2}}(5.9(Y_0^{1/3} - \frac{2}{3}) + 0.042(Y_0 - 30)^{1/3}) - 14.3993)</math>
| |
| :<math>C = 1 + \frac{0.042(Y_0 - 30)^{1/3}}{Y_0^{1/3} - \frac{2}{3}}</math>
| |
| | |
| Convert the XYZ values to [[RGB]] using the linear matrix transformation:
| |
| | |
| :<math>
| |
| \begin{bmatrix}R\\G\\B\end{bmatrix}=
| |
| \begin{bmatrix}
| |
| 0.7990&0.4194&-0.1648\\
| |
| -0.4493&1.3265&0.0927\\
| |
| -0.1149&0.3394&0.7170
| |
| \end{bmatrix}
| |
| \begin{bmatrix}X\\Y\\Z\end{bmatrix}
| |
| </math>
| |
| | |
| Last, calculate '''a''' and '''b''':
| |
| | |
| :<math>a = -13.7R^{1/3} + 17.7G^{1/3} - 4B^{1/3}</math>
| |
| :<math>b = 1.7R^{1/3} + 8G^{1/3} - 9.7B^{1/3}</math>
| |
| | |
| and multiply them by '''C''' to obtain OSA-UCS '''g''' and '''j''':
| |
| | |
| :<math>g = C*a</math>
| |
| :<math>j = C*b</math>
| |
| | |
| == See also ==
| |
| | |
| *[[Color space]]
| |
| *[[Color order system]]
| |
| *[[Munsell color system]]
| |
| *[[Optical Society]]
| |
| *[[CIEXYZ]]
| |
| *[[CIELAB]]
| |
| *[[CIELUV]]
| |
| *[[David MacAdam]]
| |
| | |
| == References ==
| |
| {{reflist}}
| |
| | |
| [[Category:Color space]]
| |
CMS provides the best platform to create websites that fulfill all the specifications of SEO. Medical word press themes give you the latest medical designs. I thought about what would happen by placing a text widget in the sidebar beneath my banner ad, and so it went. If you are using videos on your site then this is the plugin to use. It's as simple as hiring a Wordpress plugin developer or learning how to create what is needed.
Thus, it is imperative that you must Hire Word - Press Developers who have the expertise and proficiency in delivering theme integration and customization services. If a newbie missed a certain part of the video then they could always rewind. A Wordpress plugin is a software that you can install into your Wordpress site. You can up your site's rank with the search engines by simply taking a bit of time with your site. If you cherished this article and you would like to be given more info regarding wordpress backup plugin nicely visit the web site. That's a total of 180$ for each Wordpress theme if you sell 3 links and keep the designer link for your own website, or 240$ if you sell all links.
But before choosing any one of these, let's compare between the two. To sum up, ensure that the tactics are aiming to increase the ranking and attracting the maximum intended traffic in the major search engines. We can active Akismet from wp-admin > Plugins > Installed Plugins. Every single Theme might be unique, providing several alternatives for webpage owners to reap the benefits of in an effort to instantaneously adjust their web page appear. If you have any questions on starting a Word - Press food blog or any blog for that matter, please post them below and I will try to answer them.
Digg Digg Social Sharing - This plugin that is accountable for the floating social icon located at the left aspect corner of just about every submit. Quttera - Quttera describes itself as a 'Saa - S [Software as a Service] web-malware monitoring and alerting solution for websites of any size and complexity. A higher percentage of women are marrying at older ages,many are delaying childbearing until their careers are established, the divorce rate is high and many couples remarry and desire their own children. The most important plugins you will need are All-in-One SEO Pack, some social bookmarking plugin, a Feedburner plugin and an RSS sign up button. Where from they are coming, which types of posts are getting top traffic and many more.
Yet, overall, less than 1% of websites presently have mobile versions of their websites. Sanjeev Chuadhary is an expert writer who shares his knowledge about web development through their published articles and other resource. Offshore Wordpress development services from a legitimate source caters dedicated and professional services assistance with very simplified yet technically effective development and designing techniques from experienced professional Wordpress developer India. This is because of the customization that works as a keystone for a SEO friendly blogging portal website. Likewise, professional publishers with a multi author and editor setup often find that Word - Press lack basic user and role management capabilities.