14
votes
Accepted
Should the alpha channel be gamma corrected
We know that in PNG,BMP,etc... the pixel value stored is not in the linear RGB space.
This is not necessarily true. You can store whatever color space you want into an image, it doesn't even need to ...
- 1,353
12
votes
Accepted
How are we supposed to fix brightness with square roots?
What the video is talking about is called gamma correction and it's a very familiar topic for graphics programmers. The first 30 minutes of John Hable's talk on Uncharted 2 rendering is my favorite ...
- 24.8k
10
votes
Accepted
Tone Mapping vs Gamma Correction
I think it would be a good idea to get back to the basics. It's a large post, so there's a recap at the end.
Colour can be represented in a couple of ways. We can have Red, Green and Blue (RGB). We ...
- 1,595
7
votes
Accepted
Gamma correction is done in an image or a monitor?
Is every image from the internet commonly got gamma corrected?
Every image is encoded with a color profile. Most color profiles do have a gamma correction, but not every color profile has that (raw ...
- 1,595
7
votes
Accepted
Applying correct light physics to gaussian blur formulas for glow
Yes, your theory is correct. A gamma-correct blur entails converting the input pixels to linear color space, performing the blur weighting and accumulation in that space, and then converting back to ...
- 24.8k
6
votes
Accepted
Artifacts when gamma correcting
Short answer, set the precision of the image to a higher value.
Long answer,
When looking at a gamma correction curve, you can see that the lower values get changed much more, this means that the ...
- 1,595
5
votes
Why shouldn't Bump, Normal and Displacement maps be gamma corrected?
The fact that a photo is stored in gamma space doesn't have to do with PNG or JPEG, it has to do with the fact that it's a photo.
The camera detects a 50% intensity but is going to save it as a 187 ...
- 4,380
4
votes
Accepted
Does a gaussian blur based bloom/glow shader require gamma correction? Any other tips?
In short:
You should not gamma correct your glow map. In fact, you should do everything in a linear color space. At the very end, when doing any color grading (which is the very last step), you ...
- 1,595
3
votes
Should the alpha channel be gamma corrected
Image file formats themselves do not regard the gamma but store pixel values unmodified as the authoring program (e.g. Photoshop) decides to store the values, so RGB and alpha channels have no ...
- 3,616
3
votes
Question about function for color
The actual color of a pixel, outputted on a monitor, does not linearly depend on the applied voltage signal for that pixel. For CRT monitors, the actual color is approximately proportional to the ...
- 1,044
3
votes
Accepted
Why shouldn't Bump, Normal and Displacement maps be gamma corrected?
Introduction
It depends on how you create the map! Consider the following and let it sink in for a while before you go forward:
The image is displayed with a gamma correction for the benefit of your ...
- 8,397
3
votes
Why shouldn't Bump, Normal and Displacement maps be gamma corrected?
JPG, PNG or any other 8 bit image formats do not intrinsically have 1/2.2 gamma associated with it. They just store values from 0-255. How that data is interpreted depends on the software that reads ...
- 434
3
votes
Why shouldn't Bump, Normal and Displacement maps be gamma corrected?
Actually, if your bump or displacement map is saved with that 0.45 gamma correction, it's wrong. These maps contain geometrical information rather than colour, and as such, should be simply encoded ...
- 882
3
votes
Accepted
Gamma setting in games - Why 3 icons?
This has to do with gamma correction.
If one pixel has red component with value of 1 (where 255 is max), the next pixel has value for red that is 2, there no guarantee that exactly twice as much ...
- 146
2
votes
Does a gaussian blur based bloom/glow shader require gamma correction? Any other tips?
You can get fancy with individual weighting on the blur maps if you want to adjust the look, but an equally weighted mix (and yes, it should be additive) will work too. I’m not sure about whether you ...
- 2,132
2
votes
Should the alpha channel be gamma corrected
Keeping alpha linear makes it unbiased towards source and destination color. It should not be gamma corrected, because it should not have been subjected to sRGB-encoding.
A specialized application ...
- 121
2
votes
Accepted
Problem on understanding gamma correction
Almost all image formats store colors gamma-encoded, so if you write out those values to a file then that's what you'll see on opening it. The pixel pickers etc operate on the same values stored in ...
- 24.8k
2
votes
Two questions on Gamma correction and Tonemapping
the colors are distorted and much brighter corresponding to (186,186,186) color value. If I don't apply gamma encoding then the image file displays the expected color that is (127,127,127).
No, the ...
- 9,697
2
votes
Accepted
Gamma Correction vs Color Picker
Your understanding is correct, and I think the image on the right looks like the more correct one. I think the root of your confusion is that the constant ...
- 24.8k
1
vote
Is anti-aliasing color processing correct in this image?
The anti-aliasing rendering is correct.
The reference gray ramp (top and bottom) is linear in sRGB color, not in brightness.
The second gray ramp made with anti-aliasing is linear in brightness. The ...
- 121
1
vote
Question about function for color
Welcome to the world of 8-bit graphics! Other answers here are excellent, and most of what you need to know is described well on Wikipedia but let me take you on a human-friendly journey of ...
- 410
1
vote
Question about function for color
Gamma correction originated as a way of correcting the output of a CRT to be a better fit for the human visual system. Modern monitors don't need to do it, but, they followed the CRT and there were ...
- 3,030
1
vote
Accepted
Converting from RGB Color Picker to Surface Reflectance
Yes, I think you're right. The values from a typical color picker would be in a gamma encoding or sRGB encoding and would need to be converted to linear to use as reflectance. This is probably just a ...
- 24.8k
1
vote
Does a bumpmap need to be linearized from sRGB when being read?
A bump map should not be linearised from sRGB, in theory.
A diffuse map or photo contains colour data, which must be encoded in a colour space. Colour spaces consist of two things, a colour gamut (...
- 1,595
1
vote
Does a bumpmap need to be linearized from sRGB when being read?
We can not answer this question. This is important, and you need to get this info from the artist (or vice versa you need to give this info to the artist before he begins) It entirely depends on what ...
- 8,397
1
vote
Gamma correction and halftone
Yes and no. The RGB values are most likely gamma compressed.
Consider gamma calibration images like the one below.
For a well calibrated monitor the gray value should look the same as the pattern of ...
- 151
1
vote
gamma transform in webGLSL: when already done or yet to be done?
This is a hard problem since the systems do not in fact tell you how it should operate. The problem is that there are several ways to address this issue:
Apply a LUT to all output
Let the system ...
- 8,397
Only top scored, non community-wiki answers of a minimum length are eligible