lab-color-space | 易学教程

Conversion of CIELab to CIELCh(ab) not yielding correct result

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问题 I am having a hard time manually converting CIELab to CIELCh with my calculator. According to http://www.easyrgb.com/en/math.php, the following is a neutral language programming code to get from CIELab to CIELCh by going from radians to degrees: var_H = arc_tangent( CIE-b*, CIE-a* ) //Quadrant by signs if ( var_H > 0 ) var_H = ( var_H / PI ) * 180 else var_H = 360 - ( abs( var_H ) / PI ) * 180 CIE-L* = CIE-L* CIE-C* = sqrt( CIE-a* ^ 2 + CIE-b* ^ 2 ) CIE-H° = var_H And on this website, it

What is perceptually uniform color space and how LAB color space is perceptually uniform? [closed]

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问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . What is perceptually uniform color space ? how Lab color space is perceptually uniform and device independent? 回答1: slhck is right: a perceptual uniform color space ensures that the difference between two colors (as perceived by the human eye) is proportional to the Euclidian distance within the given color

Boundaries of the visible gamut in a CIE color space

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问题 I would like to know if there is any mathematical way to determine the boundaries of the visible spectrum/gamut in a CIE color space ( e.g. Lab, XYZ). Thank you in advance! 回答1: mmm... this seems to be a not-so-good formulation of a valid question. As boscarol pointed it out, the boundary of the human gamut is determined by the "color matching functions" that you will decide to use, which refer to the type of "standard observer" you need, i.e., 2° (1931, often used) or 10° (1964, a bit rare)

Plot Matlab colours as vertical bars

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问题 I stumbled upon this file exchange submission, which, given a positive integer, generates that many "maximally distinguishable" colours. The tool is working great, but I would like to visualize the colours it generates with coloured vertical bands. An example, taken from the linked blog article: For the choice of colours: ans = 0 0 1.0000 1.0000 0 0 0 1.0000 0 0 0 0.1724 1.0000 0.1034 0.7241 1.0000 0.8276 0 0 0.3448 0 We obtain the vertical bands on the left that show these colours. 回答1: A

Unable find location of ColorSpace objects in PDF document

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问题 I want to identify the ColorSpace objects in PDF and fetch their location(coordinates, width and height of the colorspace) in the page. I tried traversing through the BaseDataObject in Contents.ContentContext.Resources.ColorSpaces , I can identify the Pantone Colorspaces in file (as shown in screenshot), but unable to find info regarding the location(x,y,w and h) of the object. Where can I find the exact location of the visible objects(visible on opening a document) like ColorSpaces and

Boundaries of the visible gamut in a CIE color space

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I would like to know if there is any mathematical way to determine the boundaries of the visible spectrum/gamut in a CIE color space ( e.g. Lab, XYZ). Thank you in advance! mmm... this seems to be a not-so-good formulation of a valid question. As boscarol pointed it out, the boundary of the human gamut is determined by the "color matching functions" that you will decide to use, which refer to the type of "standard observer" you need, i.e., 2° (1931, often used) or 10° (1964, a bit rare) , or something new like cvrl.org proposed 2006 observers (2° or 10°) To get the points in the CIE xy 1931

UIColor CMYK and Lab Values

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问题 Simple question, more than likely complex answer: How can I get CMYK and Lab values from a UIColor object (of which I know the RGB values if it helps)? I have found this regarding getting CMYK values but I can't get any accurate values out of it, despite it being everywhere, I've heard it's not a great snippet. CGFloat rgbComponents[4]; [color getRed:&rgbComponents[0] green:&rgbComponents[1] blue:&rgbComponents[2] alpha:&rgbComponents[3]]; CGFloat k = MIN(1-rgbComponents[0], MIN(1