Questions tagged [color]

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61
votes
4answers
19k views

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 ...
14
votes
2answers
28k views

How do I calculate the color temperature of the light source illuminating an image?

How can I calculate the (black body equivalent) color temperature of the light source illuminating a given image? Below are screenshots of Adobe Lightroom manipulating color temperature and a shift in ...
9
votes
1answer
459 views

The small red peak in the CIE standard observer

The human eye has 3 types of color cones: red, green and blue. Their spectral sensitivity peaks in short (S, 420–440 nm), middle (M, 530–540 nm), and long (L, 560–580 nm) wavelengths. See diagram ...
8
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2answers
3k views

YV12 to RGB - What is wrong with my algorithm?

I am attempting to convert YV12 to RGB using the following fragment shader: ...
8
votes
1answer
2k views

Coloring a waveform with spectral centroid or by other means

Update 8 Unhappy of having to upload tracks to the service and looking at the new release of RekordBox 3 I've decided to take another look for an offline approach and a finer resolution :D Sounds ...
5
votes
1answer
277 views

Temperature invariant color space

I'd like to build a color difference metric that will be invariant to small changes in lighting conditions. In other words, I should be able to tell that a red shirt is not the same as a blue shirt, ...
5
votes
2answers
1k views

What's the best technique to determine if the contents of two images are the same?

I need to run comparisons on the output of hundreds of frames of simple 3D-rendered characters. Perceptually, many of the frames are exact duplicates. Based on this, I assumed something like a ...
4
votes
1answer
1k views

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 ...
4
votes
2answers
92 views

Old photographies coloring

There is already a succesful question How did they color old black and white movies? on this site. Very general and correspondingly in general answered. Let me please narrow it down to just the ...
3
votes
5answers
5k views

What Is the Difference Between the Terms Color Intensity and Color Saturation?

In Digital Image Processing, what is the difference between the intensity and the saturation of a color? How would you explain the difference to a newbie?
3
votes
4answers
1k views

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 ...
3
votes
1answer
1k views

FFT of color images incorporated into an Object Recognition method?

Is there any instance where Fourier transforms of color images have been used in conjunction with other object recognition method? Any instance of usage of Fourier transforms in color images? I ...
3
votes
2answers
181 views

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. I am interested in applying it in the context of a raw image converter for digital ...
3
votes
1answer
333 views

Decorrelating Stationary Colored Gaussian Noise — Effect On The Desired Signal

So given stationary colored gaussian noise $\mathbf{n}$, I know that I can decorrelate it by first finding it's autocorrelation $R_{nn}$ and performing $R^{-\frac{1}{2}}_{nn} \mathbf{n}$. In ...
3
votes
2answers
869 views

What Is the Best Color Space to Work with for Hand Detection: RGB, HSV, or YCrCb?

I'm working on hand gesture recognition using C#. I'm using OPENCV for skin detection but its performance is not optimal. So I decided to do some filtering based on color space, but I do not know what ...
3
votes
2answers
103 views

What is state of the art in multivariate 2D image display?

If I have a 2D scalar image, it's trivial to display it with MATLAB or matplotlib type tools with the pixel values mapped via a color map, and there is any amount of literature (one example, another ...
3
votes
4answers
6k views

How to Generate False Color Palette

How to convert grayscale intensity input to something like the following image? It seems that no response (0, black) is converted to dark blue, then it goes through other colors to red. How are ...
3
votes
0answers
119 views

How to replace color in an image without changing its texture/shades or brightness?

I want to replace color in an image from another color: For that sample image is below I want to replace color such that it becomes I know it can be easily done in Photoshop but I am looking for an ...
2
votes
3answers
3k views

Problem with HSV and RGB color model

I am a beginner in digital image processing, recently I read a paper on color image contrast enhancement, In that paper authors have implemented their method in HSV color model. In my work I have ...
2
votes
4answers
134 views

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 ...
2
votes
1answer
1k views

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 ...
2
votes
2answers
1k views

Why is it easier to extract color in HSV model than in RGB?

I am following the open-cv tutorial and they claim that: In HSV, it is more easier to represent a color than RGB color-space. after which they convert the image from BGR color model to HSV, claim ...
2
votes
1answer
43 views

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 ...
2
votes
3answers
512 views

How to go about implementing a program to measure the “intensity”/“saturation” of a color in an image?

I have a task of developing an application to measure the intensity of a color in an image. I am researching about how to go about it. Intensity refers to the purity of a hue. Intensity is also ...
2
votes
1answer
1k views

Colored noises: Stationary or non-stationary?

I know for sure that white noise is considered as a stationary sound, but is that true for the rest of them? http://en.wikipedia.org/wiki/Colors_of_noise Also, can we meet some of these sounds in ...
2
votes
2answers
120 views

Object Tracing with Particular Color

I started working on a autonomous robot project in my spare time. Everything is finished except the image proccessing part. I want my robot to follow an object with particular properties. For the ...
2
votes
1answer
63 views

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 ...
2
votes
1answer
530 views

How to use the Walsh-Hadamard transform to filter 24 bit RGB color values in a localized spatial region?

After reading this Signal processing Stack Exchange article tonight, What is the Walsh-Hadamard Transform and what is it good for?, I became interested in applying the Walsh-Hadamard transform to ...
2
votes
1answer
2k views

Algorithm for Color Balancing an Image

I'm working on color-balancing images with as little input from the user of my app as possible, specifically to remove color casts caused by scanning aged paper. Photoshop's Auto Color action works ...
2
votes
1answer
291 views

What is the implementation of a low-, mid- or high tone dodge or burn in the GIMP?

In The GIMP, and also in photoshop, you have the DODGE/BURN tool to enhance colors in shaded or highlighted regions, which would otherwise be blackish or whiteish. I found empirically that this filter ...
2
votes
0answers
32 views

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, ...
1
vote
3answers
207 views

Are There Good Methods for Converting Color Image to Gray Scale Image?

Converting color image to gray-scale image is often the first step of many image processing tasks. There exists many gray-scale image conversion methods. Most them, however, is to give R G B bands a ...
1
vote
2answers
1k views

CIELAB Color Clustering

I am trying to understand if there is an inherent advantage to using CIELAB for color-based segmentation. I segmented the cytoplasm from the image above, where the left image below is from RGB color ...
1
vote
1answer
1k views

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 ...
1
vote
1answer
1k views

Converting from RGB to LAB Color Space to Reduce Colors

In many papers I see the following: First we have to convert image from RGB to LAB color space to reduce colors then ...
1
vote
2answers
84 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 ...
1
vote
1answer
1k views

Correct color values on image taken with no infrared filter

I have a Raspberry Pi NoIR Camera. Which I want to take pictures with at daytime in a well lit room. Unfortunately the colors on the pictures do not look anything like you would expect from a normal ...
1
vote
1answer
150 views

How to unify the color and brightness measure of two given camera?

I have two cameras, and I'm up to perform some matching stuff on videos captured by these two cameras since I'm a CV guy. The problem is the two cameras have very different performance in terms of ...
1
vote
1answer
85 views

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)
1
vote
1answer
37 views

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 ...
1
vote
1answer
146 views

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 ...
1
vote
1answer
519 views

`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 ...
1
vote
1answer
123 views

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 ...
1
vote
2answers
602 views

Seeking segmentation methods for this light microscope image

Although I am not new to math or programming, I am a total newbie to image segmentation. I have the following light microscope image and I would like to segment it into cytoplasm (the magenta ...
1
vote
1answer
47 views

Getting Composition of a Mixture of Colors

I wanted to validate a thought on blending of colours digitally. Imagine I have two colours, $C_1$ $(R_1,G_1,B_1)$ and $C_2$ $(R_2,G_2,B_2)$. Now, I create colour $C3$ as follows: $C_3 = \alpha C_1 + ...
1
vote
1answer
931 views

SSD for RGB images

To compare grayscale images, I'm using SSD like the difference between the two corresponding pixels and then choose the minimum. But when it comes to RGB images, how should it works ?
1
vote
1answer
723 views

Is a change in colorspace needed when comparing colors only evaluated by the computer?

I am confused about the need to change color space for color comparison. I have read about delta E, the Lab format, and I do understand that comparisons in the RGB color space will not seem ...
1
vote
1answer
2k views

How to make color balance of photoshop using opencv

I want to make the same thing programmatically like Color balance in Photoshop , like in below image if we have same bar ...
1
vote
2answers
173 views

What are some uses of the overall colour average of an image?

As I understand, the overall colour average can be obtained by summing the individual r, g, b values of all pixels within and image and dividing by the number of pixels to produce a new tri-vector. ...
1
vote
1answer
514 views

Is the mean of visible color in CIELab color space can be non visible color?

I am converting color from RGB to CIELab to train a GMM. When I get back the mean of clusters of the GMM I have sometimes negatives values in RGB space. I was wondering if the mean of only visible ...