How to reduce color gamut in Photoshop?

I would like to see how the image will be displayed on the monitor with lower color gamut.

Am I able to mimic this using Photoshop?

Can an RGB channel be shifted to increase color gamut into the violet range?

TL;DR: Can additive RGB color gamuts produce the perception of light with higher frequency than the Blue component? If not, does pushing the highest-frequency “Blue” component increase the range of human-perceptible colors producible by the gamut? Is that not done due to technical obstacles?

Digital photography and light projectors typically use an RGB (Red + Green + Blue) color model, which at least superficially makes sense because it approximately corresponds to the peak responses of the three human color receptors:

Human photoreceptor spectral response curves

But humans can perceive light with higher frequency than “blue.” Spectrally we refer to that higher-frequency color region as “violet” or purple:

Visible spectrum

It is not physically possible to produce light with a frequency higher than the Blue component through any combination of RGB color projectors.

We know that a standard RGB color gamut does not cover the range of perceptible frequencies. Here is a standard gamut coverage chart, with the gray area indicating “colors” that cannot be produced by any combination of the RGB source:

RGB color gamut

Considering the violet region: There is a region in the RGB gamut we refer to as “violet,” which is a combination of red and blue. But referring back to the photoreceptor response curves it is distinguishable from true violet because true violet barely stimulates the red photoreceptors.

If we increase the frequency of the highest-frequency component of a 3-color projector – i.e., we increase the frequency of “blue,” pushing it towards the “violet” limit of human color perception – do we not increase the coverage of the projector gamut?

I suspect the answer is “Yes. But: the blue photoreceptors are not excited as strongly by the violet frequency. The RGB frequencies were picked to correspond with the peaks response frequency of each photoreceptor. If you shifted the blue frequency towards violet (call this an RGV gamut) then your projector would have to be able to output more violet light than the red or green channels in order to cover the rest of the unshifted gamut.” If that’s correct then this is a technical issue, and not one that seems particularly challenging. For back-lit projectors, which produce color by filtering a white source, the red and green filters would have to be recalibrated to cut more light than the violet filter.

However the answer might be, “No: See that region between blue and green? No matter how you boost your boosted violet channel it just can’t reach into it as far as a centered blue channel.” (I think the only way to reach this answer would be to have complete parameters of the photoreceptor response curves to spend some time linear programming.)

color – Why does my white picture have a blue hue? And brighter/darker horizontal waves?

Two main things apply here that affect the result you got.

  • When your camera meters a scene it assumes some of the scene is composed of lighter shades, some of it is composed of medium shades, and some of it is composed of darker shades. Absent of any instructions from you to the contrary, it will attempt to expose the scene so that the result is of medium brightness. But when you have a scene that is primarily white you probably don’t want a medium gray result – you want the whites to look white. But your camera can’t tell the difference between white and grey, and so it will normally expose for grey. You have to tell it to expose brighter using exposure compensation, probably at around +1.5 to +2 stops. The same is true of very dark objects, your camera can’t tell grey from near black either. But in that case you need to dial in -1.5 to -2.0 stops of exposure compensation.
  • Fluorescent and some LED lights flicker. Not only does the brightness vary, but so does the temperature of the light. Peaks are bluer, valleys are yellower. Some people can actually see fluorescent lights flicker, but most of us can’t. Cameras certainly can, though! If your images show the effects of flickering lights, the best way to combat this when neither the camera nor the subject is in motion is to reduce the ISO and aperture and use a longer shutter time. By catching several cycles of the peaks and valleys of the light flicker the light should even out. So if your image is showing the effects of flicker, slowing the shutter time down when possible will help.

In your image, though, I’m not convinced the variation in brightness is caused by light flicker. It may just be an indication that that your lights project an uneven pattern of brightness.

Even with the JPEG file, increasing brightness and using the eyedropper tool to “pick” the white balance gives a more natural looking result. If the raw file were available a true WB correction could be done. But WB is “baked in” when the data from the sensor is converted to JPEG. And the color cast near the hot spot in the upper right is another indication that you have uneven illumination from your lights.

semi-corrected image

Magento 2 color swatches on product listing need show more

I need color swatches on product listing show 4 color in row and on click of more,
show Remaining color swatches images Please see screenshot
How can I achieve this programmatically??
enter image description here

binary – How to display image in color as well as create histogram of grayscaled image?

I would like to know how I can display an image in color, then convert that image to both greyscale and binary, and lastly create a histogram from the greyscale version. It would also be helpful to be able to print the area of the binary/greyscale image in pixels in the console. Right now my original image is in greyscale as soon as I display it, and I would like to have that in color. I am reading in two images, ‘heart_rotated’ and ‘mole_1’. I believe that I have the histograms setup properly for each, but because I am reading them in incorrectly, the histograms are improper. Here is my code, and thank you very much!

import matplotlib.pyplot as plt
from skimage import data #built in images .camera and .cell for test
import skimage.transform as transform
from skimage.color import rgb2gray
from skimage.exposure import histogram
from skimage.filters import threshold_minimum #automated threshold
from skimage.filters import try_all_threshold 
from skimage.filters import threshold_mean  
import skimage.filters
import matplotlib.image as mpimg
import numpy as np
import skimage.morphology as morph
import skimage.measure as meas
from skimage.measure import regionprops
import cv2
import math
import sklearn

hr2 = cv2.imread('heart_rotated.png', 2)
thresh = threshold_mean(hr2)
binaryhr2 = hr2 < thresh
grayhr2 = rgb2gray(hr2)


plt.figure(1)

hr2hist, bin_edges = np.histogram(binaryhr2, bins = 256)
plt.title('Grayscale Heart Rotated Histogram')
plt.xlim((-0.2,1.2))
plt.plot(bin_edges(0:-1), hr2hist)
plt.show()
fig, axes = plt.subplots(ncols = 3, figsize = (8, 8))
ax = axes.ravel()
ax(0) = plt.subplot(1, 3, 1)
ax(1) = plt.subplot(1, 3, 2)
ax(2) = plt.subplot(1, 3, 3)


plt.figure(2)
ax = axes.ravel()
ax(0).imshow(hr2, cmap = plt.cm.gray)
ax(0).set_title('Heart Rotated')

ax(1).imshow(grayhr2, cmap = plt.cm.gray)
ax(1).set_title('Grayscale Heart Rotated') 

ax(2).imshow(binaryhr2, cmap = plt.cm.gray)
ax(2).set_title('Binary Heart Rotated')

for a in ax:
    a.axis('off')
plt.show()


mole = cv2.imread('mole_1.png', 2)
thresh = threshold_mean(mole)
binarymole = mole < thresh
graymole = rgb2gray(mole)


plt.figure(3)

molehist, bin_edges = np.histogram(binarymole, bins = 256)
plt.title('Grayscale Mole  Histogram')
plt.xlim((-0.2,1.2))
plt.plot(bin_edges(0:-1), molehist)
plt.show()
fig, axes = plt.subplots(ncols = 3, figsize = (8, 8))
ax = axes.ravel()
ax(0) = plt.subplot(1, 3, 1)
ax(1) = plt.subplot(1, 3, 2)
ax(2) = plt.subplot(1, 3, 3)


plt.figure(4)
ax = axes.ravel()
ax(0).imshow(mole, cmap = plt.cm.gray)
ax(0).set_title('Mole')

ax(1).imshow(graymole, cmap = plt.cm.gray)
ax(1).set_title('Grayscale Mole')

ax(2).imshow(binarymole, cmap = plt.cm.gray)
ax(2).set_title('Binary Mole')

for a in ax:
    a.axis('off')
plt.show()

How to export RGB Vertex Color in Blender for Unity

I am currently trying to understand how I can paint my vertices in blender to then use them in my shaders in Unity. Ideally I would like to export all color channels (RGB) so that I have 3 different masks ready in my shader in Unity.

In blender I have used the vertex painting mode and painted a simple sphere in blue on the x-axis and in red on the y-axis. When I exported the fbx and had a look in Unity there were two problems:

  1. The red and the blue channel seem to be mixed up
  2. One channel was painted ontop of the other channel and “erased” data from the other color channel

Why are my color channels mixed up (do I have to tick certain boxes while exporting?) and how can I paint the channels separately and still export them all together inside the fbx?

cheers

color – Coloring data points with LabelingFunction included

I have a plot generated by:

ListPointPlot3D[data -> labels, PlotTheme -> "Scientific",  LabelingFunction -> Center]

and I want to color the data labels. ColorFunction would work if LabelingFunction was not included. Is there a way to change the color with LabelingFunction included?

Why do white people refer to people of color as “black” people? Don’t they realize how offensive that is to us?

Please don’t use white. We’re varying shades of white.

Umm. White devil, piggy, whitewash, etc. Of course, I’m being sarcastic. It’s pretty crazy to assert that because some people have negative connotations with something, that something shouldn’t be used. There are plenty of people who will also be offended by “people of color” given its resemblance to “colored people” as a racial divider in the past. There’s always a way to demonize the language with vague “connotation” arguments. So, instead, let’s focus on what the person is actually saying, rather than make assumptions.

srgb – color spaces and monitors

What happens when retouch an Adobe rgb image in a monitor that only displays srgb?

I normally work on Adobe rgb mode and on a monitor that displays this color space. However, I am going to be using an srgb monitor for a couple of months and I am wondering if this might be a problem. I understand I would be seeing it differently when looking at it in the srgb monitor, but if I keep retouching in Photoshop in Adobe rgb color space and export it as such, would it make any difference to the final output? Thanks.

Should submit button colors match color scheme or be consistent across products?

The consistency of the design is not done by the choice of colors or its quantity, but by the design itself. The color is just one more component within the design guidelines.

If you define color variability in the design guidelines as a design component, the color change in the buttons can be an element of manifestation of this variable, provided that the shape of the buttons is sufficiently personal and recognizable.

A clear and extreme example of the use of different colors in design is the Carrefour supermarket logo. Although one of the basic canons in corporate image is the consistency of unique and representative colors, when Carrefour presented its new design in 2009, it did so with a considerable number of gradients to be used in its different communication needs.

enter image description here

Page from the Carrefour Brand Book

I think the problem is not the color of the buttons in relation to the theme of each product but the color of the buttons in relation to the design guidelines of your website.

This design guidelines can define that all the buttons must keep the same color or vary according to the theme, both options are valid.