RGB Color Spaces

If you have an idea for a new feature or other improvement to Curvemeister, this is the place to propose, discuss, and even vote on it. All suggestions are welcome, even the ones that are impossible!
mikemeister_admin
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Postby mikemeister_admin » Mon Jul 26, 2010 2:23 pm

Hi Mike,

I recant my previous suggestion about incorporating RGBW into CM4 - I've a much more exciting idea!

When users select the RGB radio button in CM, CurveMeister currently uses the working space selected in Photoshop's Color Settings window. Within CM there is no way to assign a different RGB color profile. This is where things could get really interesting ;)...

Take a look at the image that I have attached to this post*. The image shows four different looks; none of them were corrected. The different versions were created by assigning different RGB color profiles to the file - beyond that they are untouched.

In my own workflow I like to deliberately assign different profiles to images I work on: false profiles that I have created with odd gamma settings, or profiles with different gamuts, to change image saturation.

The profiles that I used in the example I have attached were created by photographer Joseph Holmes (www.josephholmes.com/propages/AboutRGBSpaces.html). They have been designed to better encompass the range of colours that photographs are likely to contain (there are several variants depending upon the subject matter that particular photographers like to shoot). Additionally, Holmes creates - for each variant - profiles that manipulate the chroma of the image (that is what the -52 and +52 values mean on my image). These profiles then allow you to alter saturation without shifting hue.

Over the course of CM 101 I have been rereading Professional Photoshop v5, and one point that DM made really struck me. Because the dE between colour values in large gamut working spaces (like ProPhoto RGB) is larger than smaller gamut spaces, small gamut spaces are easier to curve, because they are more tolerant of curve moves. Margulis uses neutrals as an example: in sRGB if RGB values are not identical (but are within a couple of points of one another) no one will notice; in ProPhoto RGB (and Adobe RGB), if these values are not identical people will notice.

Therefore what I would like to suggest is that CM4 allows users to switch spaces within the app. The app could use its own profiles - you could create gamma and chroma variants for people to select. I've been thinking about the UI, and I think it would be nice to switch between variants with a slider (the brightness slider in the Wizard could actually switch between gamma variant profiles). If somebody is struggling with a curve that is difficult to fine-tune, it would be great for them to be able to jump into a smaller gamut space, so that they can gain greater control of the adjustment points.

I'm sure that doing something like this from scratch would be a huge amount of work. I was thinking that perhaps you ought to talk with Joseph...

The payoff is that quality is boosted by an astonishing amount - and the UI allows users greater control over their curves. In addition to zooming the curve panel, allowing corner points, and exposing the existing bezier handles to the user for direct manipulation, this will make us all feel like heart surgeons!

I know that you can't make promises - but please at least let me know what you think of Joseph's profiles won't you ;)

All the best,
Lee.

*The image is by Hans F. Meier, and was purchased from iStockPhoto - http://bit.ly/coX2Qj
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-default
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Postby -default » Tue Jul 27, 2010 10:36 pm

Wow - there's a lot to think about in this article.  Adding other color spaces would certainly be possible, once the CM color engine were changed to use something like littlecms to do its own profile conversions. 

I find the idea of using a slider to change between profiles intriguing, particularly if profiles were being generated on the fly.

Re the curve interface - I am in the process of moving the curve controls into the main body of curvemeister, instead of having them use the ActiveX interface - I believe this is behind most of the strange 64 bit issues people have been reporting, including install issues.  A large amount of effort went into accommodating the ActiveX interface, and things like curve zooming, etc, have been more difficult to add as a result.

I'm interested in other people's comments.

BTW  - the "can't make promises" phrase is true enough, but I should mention that the reason for it is this continuing problem with the 64 bit beta.  Until that is solved, I don't have the time to do other

Good thoughts here, and I'd like to hear what other folks (nudge, Greg) have to say.

ggroess
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Postby ggroess » Wed Jul 28, 2010 7:15 pm

These are the questions I have without getting too deep into the waters here...
I have read about 1/2 of the article and will be finishing it later today....I may yet retract my questions but I wanted to respond...

Greg



When users select the RGB radio button in CM, CurveMeister currently uses the working space selected in Photoshop's Color Settings window. Within CM there is no way to assign a different RGB color profile. This is where things could get really interesting ;)...

The default assumption is that they are using the same color space as Photoshop. This will complicate the interface.  How about and Advanced button that enables this functionality and changes the interface so that the beginning users will not be overwhelmed by all the controls and the advanced users could access this quickly.  Kind of like the wizard...

In my own workflow I like to deliberately assign different profiles to images I work on: false profiles that I have created with odd gamma settings, or profiles with different gamuts, to change image saturation.

The profiles that I used in the example I have attached were created by photographer Joseph Holmes (www.josephholmes.com/propages/AboutRGBSpaces.html). They have been designed to better encompass the range of colours that photographs are likely to contain (there are several variants depending upon the subject matter that particular photographers like to shoot). Additionally, Holmes creates - for each variant - profiles that manipulate the chroma of the image (that is what the -52 and +52 values mean on my image). These profiles then allow you to alter saturation without shifting hue.

I worry that these are specific to his work flow and equipment set up.  Will we be adding to the color control issues that many new users have??

Are these all within the sRGB or Adobe RGB Space?  The resultant file has to go out to a output device...I'm thinking out of Gamut issues here...I know from LAB work that I can and do create problems that i have to go back and solve...

Therefore what I would like to suggest is that CM4 allows users to switch spaces within the app. The app could use its own profiles -

OK...But I want my profile included...Signed "J. Custom ProfileGuy" Apple User....I'm kidding.. but not really..where do you draw the line on included profiles?

you could create gamma and chroma variants for people to select. I've been thinking about the UI, and I think it would be nice to switch between variants with a slider (the brightness slider in the Wizard could actually switch between gamma variant profiles). If somebody is struggling with a curve that is difficult to fine-tune, it would be great for them to be able to jump into a smaller gamut space, so that they can gain greater control of the adjustment points.

Absolutely...but again how does the gamut change accommodate colors that are out..or worse...CMYK.  Maybe I'm all wet here...I'm not 100% on this one....




mikemeister_admin
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Postby mikemeister_admin » Thu Jul 29, 2010 3:18 pm

The default assumption is that they are using the same color space as Photoshop.

Because CM currently operates as a Photoshop plug-in; if CM evolves into an application the best option might be to default to Adobe (1998) RGB (or an equivalent).
This will complicate the interface.

That assumes a poorly designed UI. If this is implemented well in the UI it needn't appear complicated. Between us I'm sure we can come up with something special.
I worry that these are specific to his work flow and equipment set up.

Joseph's profiles are not built specifically for his own images. I read somewhere on his site that he had analysed ~4000 images (different subject matter, different locations) in order to determine the colors that tend to appear in photographs. The problem with Photoshop's working space profiles is that they devote too much space to colours that photographers don't encounter (which means that there's less space devoted to the colors that your images actually contain).
Will we be adding to the color control issues that many new users have?

Again, that depends entirely upon the UI implementation. I'm thinking that this will all happen behind the scenes, with users making visual decisions (perhaps using sliders). Choosing a cryptic profile from an enormous list would be a bad direction to take.
The resultant file has to go out to a output device...I'm thinking out of Gamut issues here...

In actual fact these profiles result in much better prints, because they deliver better information to the printer (this is mentioned later in the article).
where do you draw the line on included profiles?

Well, being that the end user shouldn't be aware that they are (visually) manipulating profiles (they will think that the sliders, etc. are just helping them make their image look better), I think that the line only needs to be drawn when the quality begins to suffer.

Whether or not this is viable depends entirely upon Mike's will to make it happen and a great UI design. I'm sure that between us we could come up with a phenomenal UI design ;D

Lee  :)


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