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Author Topic: Color management myths and misinformation video  (Read 79747 times)

digitaldog

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Re: Color management myths and misinformation video
« Reply #80 on: August 29, 2014, 10:09:35 pm »

Soon, soon...
Maybe but my point is, today one could say the population of New Mexico is larger than New York if one doesn't specify the population of specifically what. It is true for buffalo and untrue if we assume humans. It's probably not a good idea to say "Adobe RGB has more colors than sRGB" without laying out a lot of caveats first.
« Last Edit: August 29, 2014, 10:21:25 pm by digitaldog »
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digitaldog

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Re: Color management myths and misinformation video
« Reply #81 on: August 29, 2014, 10:10:49 pm »

Perhaps a more correct way to say it is that an image in the AdobeRGB color space can contain more colors than one in the sRGB color space.
The color space does not "have" the colors, the image does.
The "can" then changes to "has" when you have identified a particular image and determined if it does or does not.
I like that!
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Slobodan Blagojevic

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Re: Color management myths and misinformation video
« Reply #82 on: August 29, 2014, 10:13:56 pm »

Perhaps a more correct way to say it is that an image in the AdobeRGB color space can contain more colors than one in the sRGB color space...

Since we always assume, for all practical purposes, that when we say "Adobe RGB" we mean "an image in the  AdobeRGB color space," (i.e., it is a shorthand), thus we can then say that Adobe RGB has more colors than sRGB.

digitaldog

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Re: Color management myths and misinformation video
« Reply #83 on: August 29, 2014, 10:17:52 pm »

Since we always assume, for all practical purposes, that when we say "Adobe RGB" we mean "an image in the  AdobeRGB color space," (i.e., it is a shorthand), thus we can then say that Adobe RGB has more colors than sRGB.
Not necessarily. Again, the image content and the encoding need to be considered. Eyeball summed it up best thus far and a key part of that was: The color space does not "have" the colors, the image does.
A gray card? A Macbeth? Bill's flowers?
update: we should not always assume. My people vs. buffalo example comes to mind.
« Last Edit: August 29, 2014, 10:20:21 pm by digitaldog »
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Slobodan Blagojevic

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Re: Color management myths and misinformation video
« Reply #84 on: August 29, 2014, 10:20:57 pm »

However, under no circumstances or caveats we can say that sRGB can have more colors than Adobe RGB. Nor we can say that sRGB can have the same amount of colors as Adobe RGB.

mrenters

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Re: Color management myths and misinformation video
« Reply #85 on: August 29, 2014, 10:23:57 pm »

However, under no circumstance or caveats we can say that sRGB can have more colors than Adobe RGB. Nor we can say that sRGB can have the same amount of colors as Adobe RGB.

For a given image it is possible.  Consider a white canvas.  Total number of colours in sRGB and AdobeRGB is 1.

Martin
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digitaldog

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Re: Color management myths and misinformation video
« Reply #86 on: August 29, 2014, 10:25:01 pm »

However, under no circumstances or caveats we can say that sRGB can have more colors than Adobe RGB. Nor we can say that sRGB can have the same amount of colors as Adobe RGB.
With proper explanation without assumptions, yes, sRGB could easily have more colors than Adobe RGB (1998). Bills photo of flowers in sRGB vs. a photo of a gray card in Adobe RGB comes to mind.
Again, the image, which has a gamut, which can be plotted in ColorThink is nearly as important a factor as the color space you are referencing. As both Eyeball and Mark have pointed out, a color space all by itself is like one hand clapping. There is no color as yet. You have to introduce an image into all this.
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Slobodan Blagojevic

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Re: Color management myths and misinformation video
« Reply #87 on: August 29, 2014, 10:27:23 pm »

With proper explanation without assumptions, yes, sRGB could easily have more colors than Adobe RGB (1998). Bills photo of flowers in sRGB vs. a photo of a gray card in Adobe RGB comes to mind...

Oh, come on! You have to assume the same image.

digitaldog

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Re: Color management myths and misinformation video
« Reply #88 on: August 29, 2014, 10:29:43 pm »

Oh, come on! You have to assume the same image.
You didn't say that. I didn't assume it. Again, you need to be clear and define what you're talking about; people or buffalo.
You really don't get that using a simplistic statement "Adobe RGB has more colors than sRGB" is as dumb as saying NM has a larger population than NY? After all these posts?
Do you know the old saying about assumptions?
« Last Edit: August 29, 2014, 10:31:51 pm by digitaldog »
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mrenters

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Re: Color management myths and misinformation video
« Reply #89 on: August 29, 2014, 10:35:44 pm »

You didn't say that. I didn't assume it. Again, you need to be clear and define what you're talking about; people or buffalo.
You really don't get that using a simplistic statement "Adobe RGB has more colors than sRGB" is as dumb as saying NM has a larger population than NY? After all these posts?
Do you know the old saying about assumptions?

Can we agree on:

"The AdobeRGB98 colour space has the capability of representing more human perceivable colours than the sRGB colour space. A given image may, or may not, take advantage of this potential depending on subject matter."

Martin
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Slobodan Blagojevic

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Re: Color management myths and misinformation video
« Reply #90 on: August 29, 2014, 10:37:17 pm »

Andrew, it goes without saying it must be the same image for comparison purposes. You know, apples with apples, oranges with oranges.

Ah, the lengths you guys are going to go just to avoid admitting that, in plain English, and for all practical purposes, "Adobe RGB has more colors than sRGB."

Sheldon N

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Re: Color management myths and misinformation video
« Reply #91 on: August 29, 2014, 10:39:26 pm »

Jumping in late to this thread... but if you wanted to make a video that would be useful to the general public and would give you a voice to share correct information, you might make a video titled:

The Top 5 Color Management Errors and How to Avoid Them


You could easily make it a top ten as well. Start simple with jpg shooters and in-camera settings, then work your way into viewing images on other people's computers, then briefly into printing. Explain what the mistake was, show what the result looked like, then tell them how to fix/avoid it. Keep theory to a minimum (just enough to explain why without eyes glazing over) and give good advice that boils down to a "just do this if you don't understand what I'm saying" approach.

Putting the simple stuff early in the video would reach the right people, increasing complexity towards the end for those who are wanting to learn more. You shouldn't cover it all, maybe try to keep the video under 10 minutes.

The best way to "show up" those who spread misinformation is to produce good content.
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digitaldog

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Re: Color management myths and misinformation video
« Reply #92 on: August 29, 2014, 11:01:56 pm »

Can we agree on:

"The AdobeRGB98 colour space has the capability of representing more human perceivable colours than the sRGB colour space. A given image may, or may not, take advantage of this potential depending on subject matter."
I'm OK with that thus far....  ;D
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digitaldog

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Re: Color management myths and misinformation video
« Reply #93 on: August 29, 2014, 11:08:29 pm »

Andrew, it goes without saying it must be the same image for comparison purposes. You know, apples with apples, oranges with oranges.
IF the issue is a comparison with images, sure. But that's not the statements we see or hear from others. They show a gamut plot of two color spaces. They jump to the same conclusions you did about the size of the two triangles and say "Adobe RGB has more colors than sRGB". This thread, which has been very useful, illustrates that without an image, which has a gamut, the statement alone doesn't make sense.
Quote
Ah, the lengths you guys are going to go just to avoid admitting that, in plain English, and for all practical purposes, "Adobe RGB has more colors than sRGB."
I disagree. This is like Gary saying "just tell me what's going to be better, Adobe RGB or sRGB" based on his flawed testing. And no, not for all practical proposes, in specific situations with the rules set so no goal posts get moved. Without assumptions.
The blanket statement that a bigger triangle means more colors doesn't wash. It has NO colors. It's a container. Some of us are just tying to be accurate in our language.

And here's another question: what about encoding?
We have an image (Bills Flowers) in 16-bit Adobe RGB which we convert to sRGB. We then convert his Adobe RGB image to 8-bits. Could the sRGB image have more colors?
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fdisilvestro

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Re: Color management myths and misinformation video
« Reply #94 on: August 29, 2014, 11:45:16 pm »


And here's another question: what about encoding?
We have an image (Bills Flowers) in 16-bit Adobe RGB which we convert to sRGB. We then convert his Adobe RGB image to 8-bits. Could the sRGB image have more colors?

Volume of AdobeRGB in DeltaE^3 = 1,208,631 (Bruce Lindbloom)
Possible numbers in 8 bits x 3 channels = (255*255*255) = 16,581,375

Even in Adobe RGB, with 8 bits you are already one order of magnitude above the possible identifiable colors (if I understand correctly that a person will not differentiate between colors less than 1 DeltaE apart), and this is considering no noise (which does not happen in the real world)

So, my answer would be no, the sRGB image cannot have more colors, More numbers? yes, but they do not lead to different identifiable colors

MarkM

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Re: Color management myths and misinformation video
« Reply #95 on: August 29, 2014, 11:55:19 pm »

I would really like to see a real example where thanks to the "increased precision" of sRGB it is possible to differentiate two colors that otherwise will appear as one color in AdobeRGB due to the "lower precision" of using the same number of digits in both spaces.

Sure, it's not hard - for every AdobeRGB color value that is out of the sRGB gamut there is an one more sRGB color within the sRGB gamut than there is an AdobeRGB value. Here are 2 sRGB colors that map to one AdobeRGB color on PhotoshopCC on the Mac: [2, 255, 240] & [1, 255, 240]  - They both map to AdobeRGB [144, 255, 240].

I've attached the file I used (it's only 2 pixels so you'll need to zoom in).
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MarkM

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Re: Color management myths and misinformation video
« Reply #96 on: August 29, 2014, 11:58:43 pm »

Volume of AdobeRGB in DeltaE^3 = 1,208,631 (Bruce Lindbloom)
Possible numbers in 8 bits x 3 channels = (255*255*255) = 16,581,375

Even in Adobe RGB, with 8 bits you are already one order of magnitude above the possible identifiable colors (if I understand correctly that a person will not differentiate between colors less than 1 DeltaE apart), and this is considering no noise (which does not happen in the real world)

So, my answer would be no, the sRGB image cannot have more colors, More numbers? yes, but they do not lead to different identifiable colors

I thinks that's probably true and the real truth is just a matter of figuring what the real just noticeable difference is for color. I think this is something that is currently and actively studied in color science. We could certainly differentiate between the  concepts of number of discernible colors and the number of colorimetric values. In fact, doing so would really clear up a lot of confusion.
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fdisilvestro

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Re: Color management myths and misinformation video
« Reply #97 on: August 30, 2014, 12:17:04 am »

Sure, it's not hard - for every AdobeRGB color value that is out of the sRGB gamut there is an one more sRGB color within the sRGB gamut than there is an AdobeRGB value. Here are 2 sRGB colors that map to one AdobeRGB color on PhotoshopCC on the Mac: [2, 255, 240] & [1, 255, 240]  - They both map to AdobeRGB [144, 255, 240].

I've attached the file I used (it's only 2 pixels so you'll need to zoom in).

Mark, I understand your point and I agree that those different triplets in sRGB map to a single triplet in Adobe RGB. In my monitor, which is calibrated but not a sophisticated one, just a regular one, I cannot see any difference between them in sRGB. I look for the DeltaE between the two colors and the result that I get is 0.0211 (This might be not correct, I'll appreciate if anybody could confirm) which by definition implies that both colors cannot be differentiated

If the issue was precision, we could just move to tiff 16 bits or if that was not enough, then some high end application would handle 32 or more bits per channel, but no real need for it has been proved.

Regards

smthopr

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Re: Color management myths and misinformation video
« Reply #98 on: August 30, 2014, 12:36:15 am »

While this might be true about color spaces, in the case of this discussion, Abobe RGB does encompass all of sRGB.

I agree that this can become too abstract and we can get easily carried away in technicalities

A possible source for learning are the tutorials at Cambridge in Colour here. In this comparison between Adobe RGB and sRGB i find it useful the color gamut graphs at the bottom of the page, showing the difference when you use CIE xyz vs. CIE u'v', the latter giving a better approximation to what we really perceive

The cambridge colour site illustrations are very good.  But I think still too advanced for novices to grasp at first.  Thanks though, on the right track!
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Re: Color management myths and misinformation video
« Reply #99 on: August 30, 2014, 12:53:23 am »

Please tolerate this rather naive reply by one who understands just enough of this thread to be dangerous.

A thought experiment:
Suppose we have a chart containing many* color patches some of which are outside the gamut of sRGB. 
A strict condition is that each patch can be distinguished from each of the other patches by the human eye.
*I write many without specifying the number.  The thought experiment allows the number to be increased without limit under the condition that each patch be distinguishable from all others, by the human eye.

We photograph the chart and convert duplicate images, one in sRGB, the other in aRGB.  We view the images with color managed software on a wide gamut monitor. 

We now examine each of the images. 

1.  Is it possible that within one of the images we now observe least two patches that can no longer be distinguished?  If so, is this more likely to occur in the sRGB image or the aRGB image?

2.  When comparing individual patches between the two images, will we see differences in some (but not all) patches?

3.  If, between the two images, some patches are distinguishably different,  is this confined to the patches which were outside the sRGB gamut?

Right now my brain hurts, but I think the answers to these question may provide some insight.   

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