# Questions tagged [color]

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### Derive white balance matrix operator in YUV space

Assume that the white balance matrix operator in RGB space is $$W=\begin{bmatrix} \alpha &0 &0 \\ 0 & \beta & 0 \\ 0&0&\gamma \end{bmatrix}$$ where the constants ...
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1 vote
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### How to generate covariance matrix of coloured noise

For standard gaussian white noise, the covariance matrix is a identity matrix. What about other coloured noises (generated from standard gaussian): Brown(red), Pink, Blue, Violet? Additional details / ...
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### Is indexing of color independent from pixel sampling, or do they interact, and how?

My partner stitches, and uses sites like https://www.pixel-stitch.net/ in order to produce patterns. These sites do two things: they downsample an image in space to produce fewer pixels, but they also ...
23 views

### HSI formula inconsistency in Gonzalez & Woods

I'm confused about how the book Digital Image Processing by Gonzalez & Woods explains HSI model. It includes a double cone-shaped space for the model (like the figure below) and says every color ...
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1 vote
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### Consistent reconstruction of image from partial images

I am given a set of $N = 649$ color PNG images, each of size $W \times H \times 3 = 586 \times 689 \times 3$. The corresponding pixels in each image represent the same object. Many of the pixels in ...
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1 vote
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### Algorithm for Hue correction behind HSL sliders in image processing software

I have a project where i need to recreate hue specific hue adjustment sliders like in Lightroom/Capture One/DxO photolab. Initial image. Image after hue adjustment (Orange hue range) in DxO Photolab....
2k views

### Why color is coded with two numbers rather than one?

I was thinking why color spaces use two numbers to represent color: Lab, HSV, HSL? Is it possible to use one number and have the same or very similar properties when comparing colors as we have for ...
• 183
1 vote
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### Minimum number of patches needed to find color correction matrix (CCM)

The chart should have at least 9 distinct color patches for 3×3 CCMs (which are generally recommended). Excellent results can usually be achieved with the inexpensive, widely-available 24-patch X-Rite ...
143 views

### What Measure to Compare the Color Depth (Distribution of Colors) of Images

I am looking to compare the color depth of multiple images, in order to see which one has the best color depth. I was wondering what is the best way to compute color depth computationally? I've seen ...
44 views

### Edge Detection with a special algorithm

Studying for my finals in Image Processing. Trying to solve the following question: An image processing specialist recommended an algorithm for Edge Detection in a color image RGB. He argued that it ...
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### Simulate chromatic filter on RGB image

My question is quite similar to this one but I believe it is slightly different, which is why I am posting a new question. Given an image in RGB format, I want to know if it is possible to simulate (...
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### How can I segment areas, each of which has nearly same colors of pixels in an image?

For clarity, Nearly same colors of pixels belong to a category. Another nearly same colors of pixels belong to another category. The distinction depends on nearly same RGB values of pixels.
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### Chroma subsampling calculating bandwidth

How do I calculate the bandwidth required to transmit a UHDTV signal with a frame size of 3840 x 2160 at 50fps with a sampling rate of 8bits/sample?
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### Synthetic channel creation using linux software

I have a RGB image in FITS format (though I can easily convert it to another format if that makes things easier). I wish to use the R, G, B channel data from each pixel in the original image, weighted ...
2k views

### How to calculate the SDCM?

I have a light source that I want to know value for SDCM for it ( Standard Deviation Color Matching ) . I've been searching for hours with no clear way for it . I have the CCT , (x,y) coordinates , (u,...
74 views

### How to convert CIE xy value to gray scale value

Is there a way CIE chromaticity coordinates to gray scale value (0 to 255)? Any existing implementation in ImageJ, R or Python? Or formula? Here is the table taken from here. Purpose Description To ...
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51 views

### Several Questions Regarding Color Space Representation

As part of my seminar, I have to make a full representation on the many color spaces. I took a deep dive in the internet and on YouTube and managed to gather a lot of information. BUT I have a few ...
130 views

### Multivariate Histogram / CDF Matching for Image Color Matching

Suppose X is random variable that is spatial position in finite range, which its Cumulative Distribution Function (CDF) could be calculated easily, then if I have two random variable X and Y spatial ...
1 vote
30 views

### Extracting color information from lit regions to adjust shadow regions, HSV space

If I wanted to match the color of a shadow region to the color it is supposed to be in the lit region, would this, purely color information, be preserved in the hue of the HSV space of the image?
1 vote
136 views

### Is it okay to interpolate between overlapping areas obtained using a sliding window?

I am using a 50x50 pixel sliding window which moves left to right every pixel so that it covers a whole binary image which is about 2000x2000 pixels. In the window, the ratio value of black to white ...
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884 views

### how formula for saturation component is working in RGB-HSI conversion?

As shown in attached snapshot,chap6 of gonzalez 3rd edition How the highlighted expression for S in eq 6.2-3 is working? and what will be range of values of S? By range,i mean,maximum and minimum ...
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### which are saturation and intensity images in this figure?

The attached article talks about hue,saturation and intensity images. Where is each of them in fig6.25 ? I know that fig(b) shows Hue image but where are other two(saturation and intensity images)
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1 vote
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### Making images taken under daylight conditions appear as if they were taken at night using image processing elementary techniques

I know that these days' style-transfer GANs should be able to style-transfer day images into night images. I however prefer to do it using a set of elementary image processing manipulations, so I can ...
137 views

### What are the tradeoffs in HSB and HSV versus CIE color models in computer vision?

I coded a computer vision algorithm to detect objects in different lighting conditions using HSV. I recently read a convincing critique of HSV by Charles Poynton: HSB and HLS were developed to ...
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### How to Downsample The Chrominance Components

So I am doing an image compression project for college and am trying to create a visual demonstration of how downsampling chrominance components can reduce the amount of digital information while ...
2k views

### Calculating colour temperature from two sources of varying luminous intensity

I'd like to calculate the resultant colour temperature if I were to mix two different temperatures, each at a different intensity in lumens. I have series of LEDs in two different temperatures, and ...
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### what is the difference between YUV format and HSV format?

i wonder why HSV and YUV are different formats, even though they both works similarly (based on the brightness), if not what is the difference and i have confusions with YPbPr and YCbCr , can anyone ...
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### Localized Gamma Correction

Question: Is there an algorithm that does (what I would call) "localized" gamma correction? That is, applying different gamma corrections on different parts of an image, using a masking filter or ...
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1 vote
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### Restore RGB Values from Luminance Value?

I am not sure, but can we get RGB (Red-Green-Blue) values from calculated luminance value for each pixel? ...
180 views

### Can the colors of an image be interpreted as "virtual" Doppler effect? [closed]

In astronomy, the Doppler effect is used to estimate approximate distances to stars and other celestial bodies. Using the same principle, lets say we divide an image (photograph) in pixels and that ...
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### What Is the Correct Way to Apply Richarson Lucy Deconvolution to Luminance Data?

My question concerns the Richardson–Lucy deconvolution algorithm, which is described in Richardson's original paper - William Hadley Richardson - Bayesian Based Iterative Method of Image Restoration. ...
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1 vote
746 views

### Generating a colored waveform of an audio file?

I would like to ask on what approaches could one attempt to generate a colored waveform out of an audio file. Below are two examples of waveform coloring by commercial products along an audio sample ...
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### Why does the Y component in YCbCr represent luma/intensity?

As far as I know, the RGB to YCbCr conversion is just a linear transformation, yet the Y channel successfully captures the intensity value of each pixel. How? In other words, where do the following ...
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### Encoding YUV Color Space with Positive Numbers

I got 2 hdr rgb textures/signals. When fetched one gets bicubicly interpolated and the other bilinearly. So I was thinking I can store as YUV and store Y from each texture in the bicubic one and the ...
1 vote
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### Why is the green colour not represented as black in Cr component of YCbCr?

I am testing conversion from RGB to YCbCr in Python's pillow imaging module (formerly PIL), and am getting predictable results ...
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### HVS models and rods and cones

It is common to say that the YUV color model is inspired from the human visual system (HVS), knowing that we have many more rods than cones, and consequently, we are more sensitive to light than color....
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### SSIM(YUV) vs. SSIM(Y): Values Are Very Different

I'm seeing some weird results when trying to compare image qualities in a few different color spaces. Have a look at my graph: I want to compare with another publication, which reported PSNR(YUV) and ...
142 views

### What is the relationship between luminosity of Lab color space and intensity of HSI color space?

I am wondering whether one can simply convert the intensity of a color in HSI space to the luminosity value in Lab space. I am referring to te CIELab color space as discussed here: https://en....
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### Make use of a color scale in a random map [closed]

In my class I often need to work with color map images. I would show the image and try to make inferences/observations about different subjects. Often times I need to actually quantify some aspects, ...
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### Why is TV static noise always black and white?

Most modern day Cathode Ray Tube (CRT) televisions manufactured after the 1960s (after the introduction of NTSC and PAL standards) supported the circuit-based decoding of colored signals. It is well ...
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### Manipulating RGB color by copying channel value

I have a picture and trying to swap the RGB channel into RRB, it's like I need to change all G pixels value into R. I did that by copying the R pixel value to G and store it into a new image file (Mat)...
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### Colorimetry: Gamma/gamut colors Color/color light

I've been reading some color basic stuff and I came across with two different terms: gamut and gamma colors. By definition the difference between them may be clear. I found: Gamma: transfer ...
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### How to Describe the Color of an Image Patch?

I want to describe the color of an image patch (say, of size 5x5) centered around a pixel of an RGB image. The most straightforward way to do that is to calculate the average color over that patch and ...
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### what does it mean to have a decorrelated colour space?

I'm working on the problem of colour transfer between images. In the literature there's a common practice that consists in performing the transformations on images in what is called a decorrelated ...
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### What do the L, M and S pixel values in the LMS color space stand for exactly?

From what I read in the literature, the LMS color space is an attempt to quantify how the human retina's cone cells respond to light. More specifically, L has to deal with long wavelengths, M with ...
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### How to choose the most appropriate color space for a computer vision application?

A lot of image processing techniques used in computer vision consist (among other things) in switching from RGB to another color space (HSV, YUV, LMS...) : color transfer, visual tracking... It seems ...
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57 views

### Offset Wall Color From Reflected Image

I have a movie projector which is projecting an image on a brown wall. The projector allows me to adjust 6 values. Red brightness, Green brightness, Blue brightness. Red contrast, Green contrast, Blue ...
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### How to transform flat-field corrected spectra to those under Standard illuminant E (ideal equal energy illuminant)

My ultimate goal is to convert a flat-field corrected hyperspectral image of reflectance (360nm-780nm) to corresponding CIEXYZ image and thus device-independent color image. By flat-field correction, ...
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### How do I properly do gamut mapping for an image?

I asked this question earlier. To summarize, dithering an image with a specific palette was causing the image to look smeared and very discolored. Thanks to Olli Niemitalo, I found out my issue was ...
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