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Questions tagged [color]

Questions about the visual perceptual property deriving from the spectrum of light, usually expressed numerically according to a color model.

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1 vote
1 answer
83 views

UHD monitor showing artifacts for cetrain patterns, e.g. lighter lines, or image turns to green on purple

I wonder, why black-white pixels pattern as seen on this page http://www.lagom.nl/lcd-test/clock_phase.php is displayed wrongly by UHD LCDs (on all i tried). Please note, that it must be displayed 1:1 ...
3 votes
2 answers
286 views

Determining input color space primaries from spectrum data

If I have an output device, for which I have a known spectrum data for each of it's primaries, I should be able to calculate the CIEXYZ of its primaries using using the integral equations together ...
0 votes
0 answers
34 views

Is there a more extensive collection of OpenGL materials?

I develop a modeling program where users can choose from a set of predetermined OpenGL materials or enter their own custom materials. I would like to expand the list of predetermined materials ...
2 votes
1 answer
3k views

ACES tonemapping confusion

In different sources I see ACES tonemapping, but I see one of two possible sets of formulas: https://www.shadertoy.com/view/XsGfWV this one https://www.shadertoy.com/view/tdffDl or this I compared ...
0 votes
0 answers
8 views

DrawArrayInstanced is not rendering what it should (OPENGL)

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1 vote
1 answer
50 views

Is the light emitted by a typical white pixel actually a blue-ish purple to compensate for our greater sensitivity to the color green?

The human eye is considerably more sensitive to green light than red or blue; this is expressed in formulae which calculate an approximate overall "luminance" value for a RGB color (example)....
2 votes
1 answer
47 views

Why are YCbCr transforms defined in terms of gamma-corrected RGB?

I've learned a lot about digital color recently, and I've had the opportunity to implement several transforms in shaders, including converting between different RGB systems and converting into YCbCr ...
3 votes
2 answers
618 views

How to determine RGB values given a display spectral response curve?

I am reading Physically Based Rendering section 2.2.2 on RGB color. I am trying to understand how, given a display spectral response curves for rgb intensities, we can choose the intensities so that ...
15 votes
4 answers
6k views

For shader math, why should linear RGB keep the gamut of sRGB?

sRGB is often contrasted with "linear RGB." Images are stored on disk and passed to displays in sRGB, which is approximately perceptually uniform in intensity. Shader math is done in linear RGB, ...
0 votes
1 answer
109 views

Average luminence and auto exposure algorithm not seeming to work properly

I've been working on adding HDR rendering, auto exposure, and tone-mapping to my rendering engine, following this blog post for doing auto exposure and it sequel as well as a few side resources for ...
2 votes
0 answers
39 views

Is color saturation really related to light intensity?

In this article on Wikipedia, under saturation, it's written that "The purest (most saturated) color is achieved by using just one wavelength at a high intensity, such as in laser light. If the ...
2 votes
1 answer
60 views

value range in CIEXYZ space

When converting from sRGB to CIEXYZ I seem to be off by a factor of 100 I'm trying to convert from sRGB to CIELAB. Calculation First I need to go from sRGB to CIEXYZ. Using this formula I get i.e. ...
0 votes
0 answers
29 views

Normal blend mode math

I have one question. How to calculate source color after blending operation. For example. I have 1 - Background color (r-115, g-94, b-67, a-1) 2 - Foreground color above background color, which ...
0 votes
1 answer
80 views

Does CMYK values provide more colors than RGB?

We know that in the RGB system we have three primary colors and each of them has a value from $0$ to $255$ (or $256$ values in total). So all possible colors are $256^{3}=16777216$. But in the CMYK ...
-1 votes
1 answer
113 views

Converting ACES ap0 color space into srgb?

I'd like to know the correct when of converting ACES AP0 color space into sRGB. Let's say artists decide to pick colors outside of sRGB in AP0, will ACES handle this situation correctly, meaning no ...
0 votes
1 answer
98 views

With a light source at (0,2,0) and unit cube (from [-1,1]) using a given shading formula, how is the r,g,b for each surface calculated?

The above problem is from a past Computer Graphics exam. I am particularly confused about the explanation given, firstly for the top and bottom planes (since the direction of normal for top plane ...
1 vote
2 answers
360 views

Applying Phong illumination to a colored surface

The formula for Phong illumination as given on Wikipedia (see there for the variable definitions) is: $$I_\text{p} = k_\text{a} i_\text{a} + \sum_{m\;\in\;\text{lights}} (k_\text{d} (\hat{L}_m \cdot \...
0 votes
1 answer
25 views

Is there a way to automatically optimize imags based on predefined marker on image?

Color correction is tricky. It's always a lot of work to make everything look same. I have multiple products (clothing) to take a picture of. One is 100% red, other 100% Orange. Some are multicolor ...
0 votes
0 answers
30 views

What happens when we select lower resolutions on a high-resolution monitor?

I have a monitor with a resolution of 1360x768 (16:9), When I set the resolution to 1280x768 (5:3), 1024x768 (4:3), 800x600 (4:3), even 1920x1080 (16:9) it completely covers the screen and the monitor ...
3 votes
2 answers
277 views

Algorithm to reduce number of colors used on an image. (sRGB)

Introduction: I have a program that receives an image as input and does stuff. The more colors the image has the longer it takes for the program to finish and the less visible the difference between ...
2 votes
1 answer
260 views

Painter's algorithm test 2 and test 3?

TEST #2: Surface S is completely behind the overlapping surface relative to the viewing position. S1 is completely behind/inside the overlapping surface S2 How to check these conditions? i) Set the ...
4 votes
1 answer
324 views

How to find the nearest palette color when dithering in RGB

I maintain an image dithering library and command line tool. When I was initially developing the library, I was trying to figure out how to match dithered RGB values (containing quantization error or ...
0 votes
2 answers
242 views

Why are the HSL and HSV color models not considered "perceptually uniform"?

The HSL/HSV color spaces are not considered "perceptually uniform" despsite being widely used. Is there a detailed reason for this?
2 votes
0 answers
41 views

How to add HemisphereLight to a simple threejs scene?

I'm trying to add light and see its changes in a simple scene in threejs but no matter the intensity or the color I set for the light, I see no change in a scene. Actually, if I don't include the ...
0 votes
1 answer
457 views

Why does my Dell laptop monitor give this weird color banding?

I've noticed some very obvious color banding on the screen of my Dell Precision 7750 laptop while watching video (same in every video program; VLC, built-in Windows video player, etc.) Not only does ...
1 vote
0 answers
214 views

What are the main concepts behind building the plasma effect with GSLS?

By the plasma effect I mean an animation that looks like this: I have seen some codes, like these https://www.shadertoy.com/view/Xst3zN https://www.shadertoy.com/view/4tdGWX and messed with the code ...
2 votes
1 answer
163 views

Interpolating HSV color with black

I'm interpolating RGB values by transforming them into HSV space and then back into RGB. I have trouble figuring out how to achieve ...
0 votes
1 answer
117 views

How to visualize color synthesis in HSL diagram

before considering the HSL color space, let's consider the CIE chromaticity diagram to understand what I'm looking for: Unless I am mistaken, I read it that way: Given two points A, B, any color in ...
1 vote
1 answer
86 views

Using the Preetham/Shirley/Smits daylight model to get practical (s)RGB values

I have implemented Preetham, Shirley, and Smits’s daylight model using Aubrey Jaffer’s Scheme implementation as a reference and confirmed that my implementation produces the same results in the xyY ...
4 votes
2 answers
173 views

Confusion about HDR image pipeline

I am working on a path tracing renderer, and I want to produce an sRGB image out of the HDR image buffer I get at the end of my rendering algorithm. Up until now I have worked just by clamping values, ...
0 votes
3 answers
2k views

How do I add two color values containing alpha?

I started out writing my Color class as just containing R, G, B triplets. Adding colors in this situation turns out to be fairly simple. ...
2 votes
1 answer
207 views

Why do some texture data formats only have the red channel?

While programming something in Rust with the BevyEngine, I came across TextureFormats. My understanding is that those are used to define how the pixel data is handled. So Rgba8Unorm means that there ...
2 votes
2 answers
373 views

Why do computers more efficiently store black colors than white colors in computer graphics?

I have a question about how colors are stored in computer graphics. I had watched this video previously which had explained about why colors are stored and displayed differently than one would assume ...
1 vote
1 answer
471 views

How to change a RGB value using a radiance value?

I am new to this awesome community, I am currently writing a ray tracer but I hit a problem... Let's say I have a surface(material doesn't matter) of colour [1, 0, 0] in RGB, and the radiance reaching ...
8 votes
2 answers
3k views

What is a good color similarity metric?

I have some colors in RGB in [0,1] and want to find a way to rate their similarity, as perceived by a human. I have two ideas in mind, but I am sure there are other options as well, but am unsure ...
1 vote
1 answer
99 views

Is spectral response curve and spectral power distribution the same thing?

I'm reading section 5.2 of pbrt 3rd edition and came across the part where they explain the concept of RGB colors. When we display an RGB color on a display, the spectrum that is actually displayed ...
2 votes
0 answers
109 views

Why do materials have both an ambient color and a diffuse color?

One of the first things I learned about computer graphics lighting (and light in general) is that when a ray of light hits a surface, the surface absorbs certain colors and the light retains the rest. ...
2 votes
4 answers
256 views

Question about function for color

I would like a help to understand the following line of code: return float3(pow(color.r, 2.2), pow(color.g, 2.2), pow(color.b, 2.2)); I've seen some places calling ...
0 votes
1 answer
53 views

Animated rainbow distortion wave effect

https://foundation.app/mg/20210227-3lau-makes-history-1790 The link above shows a video animation that has a rainbow wave distortion effect applied to it, that ripples across the video. how, and in ...
0 votes
2 answers
63 views

What is the name of this moving color pixels effect, for animating a painting?

https://superrare.co/artwork-v2/spring-22267 The artwork in the link seems to be based on a painting of a woman, but effects have been added that assign a pixel to each block of the painting that ...
1 vote
1 answer
65 views

Name and influence of style used for futuristic line patterns?

What is the name of the style of the line graphics used in the image below? The line patterns seem to envelope the shape of the woman maybe algorithmically somehow, becoming denser and yellow on the ...
4 votes
2 answers
268 views

"whiteness" in center of bright colored lights - what is it called?

When a source of colored light is very bright, it's center appears white. What is the term I need to look for so I can implement this in my shader? I have added an image which is an example of what I ...
1 vote
1 answer
55 views

Colour Depth in Hardware

I hope this is the correct place to ask this question. It feels to me that I should ask people who have had to program graphics as there’s a lot of confusion about color depth in general. I’m sure a ...
1 vote
2 answers
348 views

Can I get numeric data from a color map?

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
1 answer
161 views

Raytracer help - Background color writing over some colors?

I'm implementing Peter Shirley's "Raytracer in a Weekend: The next week" and I'm having some trouble with rendering a scene with a light. I'm not sure if the issue is the background color or ...
1 vote
2 answers
68 views

splitting hue & saturating and leaving value behind

In an HSV model, the Hue is the color model. So when we split the image or remove H, should we get an image without rgb colors? Similarly, saturation is the gray shade. I read that images become more ...
1 vote
1 answer
185 views

Weird glColor3f results in framebuffer objects

The code is glColor3f(1, 1, 1); gluSphere(gluq, 0.2, 10, 10); glColor3f(1, 0, 0); glTranslatef(1, 0, 0); gluSphere(gluq, 0.2, 10, 10); In short, when I draw ...
4 votes
3 answers
4k views

Why is there a difference between the CIE XYZ colour gamut vs CIE RGB?

Yet another question about colour space... In my research on CIE XYZ system, I found that it is based on the CIE RGB colour matching experiments, and that because the RGB system needed occasional ...
0 votes
2 answers
106 views

What is the relation between colour spaces and what is actually displayed on our screens?

I am not entirely sure that this is the right stack exchange, but I couldn't find any other suitable one - please redirect me if necessary. There exists mathematically defined colour spaces which help ...
1 vote
0 answers
376 views

How could I remove this colour interpolation artefact across a quad?

I've been reading up on a vulkan tutorial online, here: https://vulkan-tutorial.com. This question should apply to any 3D rendering API however. In this lesson https://vulkan-tutorial.com/...