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Questions tagged [cielab]

In CIE LAB, LAB stands for Lightness, position between red and green, and position between yellow and blue. It is a colour space designed as more related to human perception than RGB or HSV spaces. It was proposed by the International Commission on Illumination (CIE).

CIE LAB (strictly speaking L*a*b*, as opposed to LAB in Hunter LAB) is a chromatic value colour space and is said to be the most complete colour space specified by the International Commission on Illumination (Commission internationale de l'éclairage - CIE). It describes all the colors visible to the human eye and was created to serve as a device-independent model to be used as a reference.

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Number of unique CIELab colors in an image

I have an image represented in the CIELab color space. How can I return the number of unique CIELab colors the image contains? Thanks.
Simplicity
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How can I adjust color curves in a CIE L*a*b* image in python?

In Photoshop, it is possible to adjust the color curves of L,a,and b in the CIE Lab* color space. I am attempting to perform a similar process for image enhancement using gamma correction in python. However, this only adjusts the curve in one…
Deepti Hegde
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I can't save RGB image as a Lab image

I'm trying to read an RGB 8-bit image, converting it into Lab and save it. The result is always interpreted as an RGB image and it's very strange (saturated). I tried not to normalize values or to use RGB2Lab or to convert the images to 32FC but…
Davide577
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Clarification on conversion between RGB and CIELAB

I'm working cum clouds of points with PCL. I recently had to convert the color information of the points that are in RGB to Cielab. I have seen that it is possible to do with OpenCV and then I used the following…
Tiago A. Silva
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Color Math and Programming

I am currently trying to build a program that will accept a image and replace all of its individual parts 20x20 with individual images (up to a 1000) that are a best visual match. I researched and learned about avg RGB/Color, my broad idea of how I…
adot
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How to invert a density distribution?

I'm working with the RGB cube, trying to create a maximal palette of strongly distinct colors. So I'm taking slices of the RGB cube perpendicular to the diagonal between the black and white vertices and applying the CIELab color distance formula. It…
Mike Reynolds
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Why is Delta CMC algorithm (for calculating color difference), not symmetric?

I'm implementing the Delta CMC algorithm (color difference in CIELAB space) as described here and here. I was surprised to see a calculation for the Hue of the first color but not the second color. This would most likely make the algorithm…
Mark
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How can I determine the colorspace (RGB) profile of my data?

I have a standard jpeg image, which I use within some commercial software to colorize other data (by mapping the image's color onto the data). Then I export the colored data from this software to an XYRGB ascii file, i.e. I store the data…
Michael
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Opencv L*a*b* to RGB conversion produces grayscale output

I've been assigned to change a picture from the Lab* color space to RGB using OpenCV. In order to do that I used the information presented here and here. EDIT: Was assigned to do it without the cvtColor function that comes with OpenCV. Also tried…
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valgrind: errors with cvCvtColor in opencv

Here is my very simple code: #include #include #include using namespace std; using namespace cv; int main(int argc, char** argv) { for(int i=0;i<2;i++){ ostringstream tmp; tmp <<…
Tu Bui
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RGB to CIE Lab skin color segmentation

I got problem to convert RGB to CIE Lab to get skin-colored area, I did some calculations from RGB based on this, to XYZ and finally Lab with a help from this link. Here's my code: #include #include…
Wandiw
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How to compare colors in iOS

I have a need to compare a color from an image to an array of other colors and determine which of the other colors it is most perceptually similar to. I do not know a lot about color theory. I understand that L*a*b* is the colorspace that is most…
Sarah L
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