Questions tagged [luminance]
64 questions
1
vote
2 answers
Problems with GL_LUMINANCE and ATI
I'm trying to use luminance textures on my ATI graphics card.
The problem: I'm not being able to correctly retrieve data from my GPU. Whenever I try to read it (using glReadPixels), all it gives me is an 'all-ones' array (1.0, 1.0, 1.0...).
You can…
Pedro Boechat
- 2,446
- 1
- 20
- 25
1
vote
1 answer
Dot Product and Luminance/ Findmyicone
All,
I have a basic question that I am struggling with here. When you look at the findmyicone sample code from WWDC 2010, you will see this:
static const uint8_t orangeColor[] = {255, 127, 0};
uint8_t referenceColor[3];
// Remove luminance
static…
Khaled Barazi
- 8,681
- 6
- 42
- 62
1
vote
0 answers
Building Luminance HDR on Ubuntu
I'm following the INSTALL for luminance-hdr-2.3.0, building on Ubuntu 12.04, but I'm getting the following error:
root@ben-laptop:/usr/src/luminance# cmake /usr/src/luminance-hdr-2.3.0/src
-- The C compiler identification is GNU
-- The CXX compiler…
Ben Rogers
- 21
- 3
0
votes
1 answer
Luminance calculator with 8-digit hexadecimal or RGBa colors
I am calculating the contrast of a website and finding errors. But when I have rgba or Eight-digit hex notation I don't know how calculate the Luminance.
I calculate the hexadecimal luminance with this…
Jenny Fer
- 21
- 1
0
votes
0 answers
Color contrast using relativ luminance, where does the 0.05 come from
I am currently calculating the contrast of two foreground colors and a background color to programmatically decide if the foreground color should be white or black.
The formula for the contrast ratio is defined as
(L1 + 0.05) / (L2 + 0.05)
Where…
user13523921
0
votes
0 answers
Looking for a way to replace LUX, Luminance or Color in HLSL for a Shader Graph in Unity, as 2D editing software does
I am currently writing a custom node in my Unity HDRP shadergraph. Those are done in HLSL.
My current situation: Image A is an RGBA float vector. It shall recieve the color values of Image B, which is also an RGBA float vector. If not possible,…
xDonnervogelx
- 101
- 4
0
votes
1 answer
How to get parent widget color in flutter tree widget?
I want change a color of a button depending by background color of with:
computeLuminance()
So, I need to get parent widget located by button and get its color / any that can I calculate difference between the two colors.
Color…
Antônio Alexandre
- 15
- 2
0
votes
0 answers
Increasing the Y value in a YCbCr image in Python (pillow) results desaturated image
I'm using the code below to convert from/to RGB/YCbCr images, which works properly when I don't do any adjustment over Y values.
def rgb2ycbcr(im):
xform = np.array([[.299, .587, .114], [-.1687, -.3313, .5], [.5, -.4187, -.0813]])
ycbcr =…
0
votes
1 answer
what is the constant k in calculating the luminance
I want to calculate the luminance of image using RGB value but in the formula there is a constant k i didn't know what it is this is the formula from the document:
"In calculating luminance (L), CIE Y is multiplied by a constant value ‘k’, where k…
Ameni Kaabi
- 1
- 1
0
votes
0 answers
how to compare two images based on luminosity of each pixel on matlab
I am working on a project in which I have to compare two b&w images based on their luminosity. I wanted to create a program that compares the pixels of each image using MATLAB and I wanted some advice on how I could do this.
mehta
- 1
0
votes
1 answer
Get float of UnitIlluminance from ios
I want the luminance value of iPhone. In Android we can get it using Type_Light as given here:
https://developer.android.com/guide/topics/sensors/sensors_environment
I want the same for iOS. I want the value like 80.0 or 454.0 whatever the luminance…
Shubham1212
- 35
- 5
0
votes
1 answer
Getting RGB Values of Pixels Based on Luminance in Python
Trying to figure out how to accomplish this task: I'd want to select pixels of an image based on luminance, and then grab the rgb values of those pixels.
My initial thought was to use OpenCV to make a histogram on the greyscale of the image:
img =…
CreativelyChris
- 63
- 1
- 7
0
votes
1 answer
How to set same luminance for several images?
I have a lot of images with different luminance value. And i want to set luminance of image to standard value that is 0,196 or 49,98.
And what i want is:
image that has overexposure the luminance should be decrease, and
image that has…
Putri Ranati
- 47
- 6
0
votes
1 answer
adjust image luminance imagemagick
I am trying to adjust the mean luminance of an image using imagemagick. I have converted the size and color of the images so they are now in grayscale as below:
body_heavy_female_gray_resize
next I need to adjust the luminance of each image so they…
Casey Jayne
- 69
- 8
0
votes
0 answers
how have a chrominance in RGB channels in opencv?
I have the next problem
I want to use this equation in openCV
X = blue channel , Y = green channel and Z = red channel
x = X / (X + Y + Z);
y = Y / (X + Y + Z);
Z = Z / (X + Y + Z);
But when i run my code I have a window whit 3 images on…
