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Questions tagged [color]

The tag has no usage guidance.

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1answer
21 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 ...
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0answers
20 views

Retro Tiled Image Palettization Algorithm?

In most cases today, image palettization consists of reducing the overall number of colors in an image to some fixed number globally. This is typically solved as a straightforward but computationally ...
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0answers
13 views

Amplifying the difference of luminance between pixels of color images?

I'm doing some research on digital watermarking and came across an article that embeds QR codes on mostly grayscale images and the extraction part for color images is quite confusing the article ...
0
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1answer
31 views

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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1answer
261 views

SSIM(YUV) vs SSIM(Y): values 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 ...
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0answers
20 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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0answers
153 views

Best approach to check the result of color space conversion from RGB to LMS?

I'm currently working on manipulating the order of RGB color from an image into RRB, GGB, etc. Now I need to convert this RGB value into LMS. I take this paper as a reference for the transformation ...
2
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0answers
30 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, ...
57
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4answers
16k 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 ...
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1answer
183 views

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)...
0
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1answer
152 views

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 ...
0
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1answer
74 views

how to describe the color of a small 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
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1answer
676 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 ...
1
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1answer
620 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 ...
4
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1answer
850 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 ...
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0answers
42 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 ...
0
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1answer
44 views

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, ...
0
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1answer
210 views

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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2answers
153 views

How to Reverse Color Quantization?

Are there any algorithms that attempt to perform the inverse of color quantization on an image? In other words, is there a smart way to increase the bit depth of image? The obvious answer would be to ...
1
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1answer
826 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
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1answer
83 views

Magnification of a colored image through two color space: RGB & YCbCr

I have tried to magnify a colored image using bicubic method. I did this in two ways; First, I resize R, G, and B parts of it. Second, I transformed RGB to YCbCr color space and then resized Y, Cb, ...
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2answers
985 views

Create a color image in Matlab with sinusoidal patterns

I want to create a color image in Matlab whose components have sinusoidal patterns (okay even if they have different frequencies). To create a black and white image I did: ...
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3answers
148 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 ...
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3answers
110 views

Is a real Grayscale image always 8 bit per pixel indexed?

I tested several Grayscale images downloaded from the Internet. Some of them are 8bpp indexed while others are 24bpp (true colored). Looks like different Grayscale images have different depths. For ...
2
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1answer
233 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 ...
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5answers
3k 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?
4
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0answers
112 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 ...
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2answers
390 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 ...
0
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1answer
204 views

How do I calculate correlated color temperature correctly?

How can I calculate the color temperature(CCT) of the light source illuminating a given raw image correctly? The method I used is proposed by McCamy, and the algorithm was also described in the ...
0
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1answer
410 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 ...
1
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4answers
347 views

Finding a signals complimentary sound / frequency

I know about complimentary colors and how to get them, since colors are basically frequency / wavelengths. Is it possible to find a signals complimentary, additive or subtractive frequencies in an ...
1
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2answers
930 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 ...
4
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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 ...
0
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1answer
24 views

Getting composition of a mixture of colours

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 + ...
2
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3answers
356 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 ...
0
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1answer
735 views

Converting from RGB to Lab 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 ...
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2answers
784 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 ...
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1answer
639 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
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1answer
427 views

what is the difference between HSV and CIE-Lab color space? [closed]

when do we use HSV color space and when do we use CIE-Lab color space?
0
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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 ...
0
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1answer
197 views

How to Linearise an Input Image before applying Color Correction?

I'm doing color correction on Raw images taken from Camera directly. I want to make my Camera reproduce same colors as my Target camera. Here are the steps I'm following: Take Target Color values ...
5
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2answers
830 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 ...
0
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1answer
255 views

Difference between ycbcr and ycbycr

I see in a paper mentioning ycbcr as well as ycbycr. I am wondering what is the difference between the two? In the figure, the first two lines show ycbycr but the two bottom lines show ycbycr?
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0answers
62 views

Good color distance metric for classifying color pairs

I have some two tone origami paper. This particular paper comes in six types, each with a different pair of colors. Here's an image that shows all six: Given a picture of one of these sheets, I want ...
0
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1answer
655 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 ...
8
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1answer
364 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 ...
2
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1answer
277 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 ...
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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 ...
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1answer
1k 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 ...
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2answers
61 views

Tracking using color

I am working on tracking an object in a video by using its color. what i did is that i have converted the color of a selected object into LAB color space since it is a uniform color space. and then in ...