Color management - Revision history

BryceHarrington at 02:35, 9 January 2018

2018-01-09T02:35:24Z

← Older revision		Revision as of 02:35, 9 January 2018
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	*[http://www.w3.org/TR/SVGPrint/#devcolor SVG Print mentions color issues], including expected color support in SVG 1.2		*[http://www.w3.org/TR/SVGPrint/#devcolor SVG Print mentions color issues], including expected color support in SVG 1.2
			* Sk1's code: https://github.com/sk1project/sk1-wx

	[[Category:Developer Discussion]]		[[Category:Developer Discussion]]

Frigory: Frigory moved page InkscapeColor to Color management

2016-07-13T05:55:50Z

Frigory moved page InkscapeColor to Color management

← Older revision	Revision as of 05:55, 13 July 2016
(No difference)

Mormegil: Undo revision 14241 by UyaEaw (Talk)

2009-11-26T23:15:25Z

Undo revision 14241 by UyaEaw (Talk)

← Older revision		Revision as of 23:15, 26 November 2009
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	Fill/stroke paints that mention an icc color reference a color-profile by name.		Fill/stroke paints that mention an icc color reference a color-profile by name.
	We thus need a mapping from name to color profile.		We thus need a mapping from name to color profile.
	This mapping is to be populated by handlers for the		This mapping is to be populated by handlers for the <color-profile> element and the <tt>@color-profile</tt> CSS at-rule. However, note that these handlers also need to cope with the user changing or deleting that element/stylesheet; and that there can be multiple purported definitions for a given name (in which case the last one wins). I think we want a doubly-linked list of definitions, and then we re-create the mapping (hashtable or whatever) in full when the list changes. (We don't expect the list to contain many entries, so it's cheap to rescan the whole list.) The <color-profile> element object should then include a pointer into that list, and I suppose that stylesheet objects should include multiple pointers into the list (given that stylesheets can contain arbitrarily many <tt>@color-profile</tt> at-rules). (The reason for storing a pointer rather than just storing the name is to allow for duplicate names in the list.)

			=== Links ===

			*[http://www.w3.org/TR/SVGPrint/#devcolor SVG Print mentions color issues], including expected color support in SVG 1.2

			[[Category:Developer Discussion]]

Roxton: /* What is "Color"? */

2009-04-28T22:41:09Z

What is "Color"?

← Older revision		Revision as of 22:41, 28 April 2009
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	To illustrate how this works, consider the case where you need an sRGB graphic displayed on your profiled LCD monitor. The sRGB profile is used to convert the RGB tuple in the document into a Lab tuple. Your monitor's profile is then used to convert the Lab tuple to the RGB tuple that will be delivered to your monitor.		To illustrate how this works, consider the case where you need an sRGB graphic displayed on your profiled LCD monitor. The sRGB profile is used to convert the RGB tuple in the document into a Lab tuple. Your monitor's profile is then used to convert the Lab tuple to the RGB tuple that will be delivered to your monitor.

	~~The~~ same ~~approach~~ is used ~~both for displaying graphics~~ in the Adobe RGB 1998 color space ~~and for displaying graphics in~~ a CMYK ~~color space~~ defined by ~~either~~ a ~~printing~~ industry standard profile (e.g. SWOP ~~or FOGRA~~) or a profile ~~specific~~ to a particular printer and output medium.		This same technique for displaying a graphic is used if your graphic is defined in the Adobe RGB 1998 color space, a CMYK colorspace defined by a print industry standard profile (e.g. FOGRA or SWOP), or a custom profile tailored to a particular printer and output medium.

	A common color space for the Internet is [http://www.w3.org/Graphics/Color/sRGB.html sRGB]. Adobe and HP created this color space to model the behavior of a typical computer monitor so that in the absence of any color management, the raw RGB values piped to your display hardware will appear more-or-less as the designer intended. For this reason, SVG defaults to sRGB. Likewise, CSS supports only sRGB. As a working space for ~~more broadly~~ targeted ~~design work~~, sRGB is a poor choice due to its limited gamut.		A common color space for the Internet is [http://www.w3.org/Graphics/Color/sRGB.html sRGB]. Adobe and HP created this color space to model the behavior of a typical computer monitor so that in the absence of any color management, the raw RGB values piped to your display hardware will appear more-or-less as the designer intended. For this reason, SVG defaults to sRGB. Likewise, CSS supports only sRGB. As a working space for artwork not targeted exclusively at web browsers, sRGB is a poor choice due to its limited gamut.

	And then there are [http://www.ps.missouri.edu/PS2/support/TutorialFolder/ColorTutorial/ColorTutorial2.html spot colors]. Many designers (and thus users of vector art packages) often specify spot colors that are precise matches from a book, such as [http://en.wikipedia.org/wiki/Pantone Pantone] named colors. The main thing about these is that they are supposed to be fixed single colors of a known appearance.		And then there are [http://www.ps.missouri.edu/PS2/support/TutorialFolder/ColorTutorial/ColorTutorial2.html spot colors]. Many designers (and thus users of vector art packages) often specify spot colors that are precise matches from a book, such as [http://en.wikipedia.org/wiki/Pantone Pantone] named colors. The main thing about these is that they are supposed to be fixed single colors of a known appearance.

Roxton: /* What is "Color"? */

2009-04-28T22:35:23Z

What is "Color"?

← Older revision		Revision as of 22:35, 28 April 2009
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	That is a very good question. In Inkscape, color is basically RGB value triplets. But in order to get precise, and to enable the same color to be seen on different computers, the general idea of [http://en2.wikipedia.org/wiki/Color_space color spaces] comes into play.		That is a very good question. In Inkscape, color is basically RGB value triplets. But in order to get precise, and to enable the same color to be seen on different computers, the general idea of [http://en2.wikipedia.org/wiki/Color_space color spaces] comes into play.

	A color space determines how a tuple of data values (e.g., an RGB triplet) maps to a well-defined color (and vice-versa). In software, this is commonly achieved through the use of an [http://en.wikipedia.org/wiki/Color_profile ICC profile]. In ~~this case~~, well-defined colors are defined in either the [http://en.wikipedia.org/wiki/Lab_color_space Lab color space] or the [http://en.wikipedia.org/wiki/CIE_1931_color_space CIEXYZ color space]. These are known as profile connector spaces.		A color space determines how a tuple of data values (e.g., an RGB triplet) maps to a well-defined color (and vice-versa). In software, this is commonly achieved through the use of an [http://en.wikipedia.org/wiki/Color_profile ICC profile]. In ICC profiles, well-defined colors are defined in either the [http://en.wikipedia.org/wiki/Lab_color_space Lab color space] or the [http://en.wikipedia.org/wiki/CIE_1931_color_space CIEXYZ color space]. These are known as profile connector spaces.

	To illustrate how this works, consider the case where you need an sRGB graphic displayed on your profiled LCD monitor. The sRGB profile is used to convert the RGB tuple in the document into a Lab tuple. Your monitor's profile is then used to convert the Lab tuple to the RGB tuple that will be delivered to your monitor.		To illustrate how this works, consider the case where you need an sRGB graphic displayed on your profiled LCD monitor. The sRGB profile is used to convert the RGB tuple in the document into a Lab tuple. Your monitor's profile is then used to convert the Lab tuple to the RGB tuple that will be delivered to your monitor.

Roxton: /* What is "Color"? */

2009-04-28T22:33:24Z

What is "Color"?

← Older revision		Revision as of 22:33, 28 April 2009
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	=== What is "Color"? ===		=== What is "Color"? ===

	That is a very good question. In Inkscape, color is basically RGB value triplets. But in order to get precise, and to enable the same color to be seen on different computers, the general idea of [http://en2.wikipedia.org/wiki/Color_space ~~colorspaces~~] comes into play.		That is a very good question. In Inkscape, color is basically RGB value triplets. But in order to get precise, and to enable the same color to be seen on different computers, the general idea of [http://en2.wikipedia.org/wiki/Color_space color spaces] comes into play.

	A ~~common colorspace for~~ the ~~internet is~~ [http://~~www~~.w3.org/~~Graphics~~/~~Color~~/~~sRGB~~.~~html sRGB~~]. ~~SVG defaults to sRGB~~.		A color space determines how a tuple of data values (e.g., an RGB triplet) maps to a well-defined color (and vice-versa). In software, this is commonly achieved through the use of an [http://en.wikipedia.org/wiki/Color_profile ICC profile]. In this case, well-defined colors are defined in either the [http://en.wikipedia.org/wiki/Lab_color_space Lab color space] or the [http://en.wikipedia.org/wiki/CIE_1931_color_space CIEXYZ color space]. These are known as profile connector spaces.

	~~Then there~~ is CMYK. ~~Of course,~~ this ~~is not~~ a ~~single colorspace~~, ~~but needs~~ to ~~be specified per output device~~, ~~inks~~, ~~media~~, ~~viewing conditions, etc~~.		To illustrate how this works, consider the case where you need an sRGB graphic displayed on your profiled LCD monitor. The sRGB profile is used to convert the RGB tuple in the document into a Lab tuple. Your monitor's profile is then used to convert the Lab tuple to the RGB tuple that will be delivered to your monitor.

			The same approach is used both for displaying graphics in the Adobe RGB 1998 color space and for displaying graphics in a CMYK color space defined by either a printing industry standard profile (e.g. SWOP or FOGRA) or a profile specific to a particular printer and output medium.

			A common color space for the Internet is [http://www.w3.org/Graphics/Color/sRGB.html sRGB]. Adobe and HP created this color space to model the behavior of a typical computer monitor so that in the absence of any color management, the raw RGB values piped to your display hardware will appear more-or-less as the designer intended. For this reason, SVG defaults to sRGB. Likewise, CSS supports only sRGB. As a working space for more broadly targeted design work, sRGB is a poor choice due to its limited gamut.

	And then there are [http://www.ps.missouri.edu/PS2/support/TutorialFolder/ColorTutorial/ColorTutorial2.html spot colors]. Many designers (and thus users of vector art packages) often specify spot colors that are precise matches from a book, such as [http://en.wikipedia.org/wiki/Pantone Pantone] named colors. The main thing about these is that they are supposed to be fixed single colors of a known appearance.		And then there are [http://www.ps.missouri.edu/PS2/support/TutorialFolder/ColorTutorial/ColorTutorial2.html spot colors]. Many designers (and thus users of vector art packages) often specify spot colors that are precise matches from a book, such as [http://en.wikipedia.org/wiki/Pantone Pantone] named colors. The main thing about these is that they are supposed to be fixed single colors of a known appearance.
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	*sRGB color		*sRGB color
	*spot color		*spot color
			*RGB and CMYK colorspaces defined by ICC profiles

			There are two different problems: firstly, displaying a composite image composed of several spot colours. This is easy - just represent the spot colours with their rgb approximations. The only work is at the interface and colour lookup phase - implementing schemes or palettes solves this straight off. The second problem is generating PostScript or png with the colours separated correctly. PostScript handles this readily with the /DeviceN color space, whereas output to PNG would involve masking occluded artwork. A more sophisticated approach would need to address [http://en.wikipedia.org/wiki/Spreading_and_choking trapping] and [http://en.wikipedia.org/wiki/Overprinting overprinting].
	*colorspace definition

	There are two different problems: firstly, displaying a composite image composed of several spot colours. This is easy - just represent the spot colours with their rgb approximations. The only work is at the interface and colour lookup phase - implementing schemes or palettes solves this straight off. The second problem is generating ~~postscript~~ or png with the colours separated correctly. ~~This is hard~~.

	=== Color Management ===		=== Color Management ===

JonCruz: /* Color Management */

2008-08-27T08:32:05Z

Color Management

← Older revision		Revision as of 08:32, 27 August 2008
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	[[LittleCMS]] also has its own VERY ACCURATE COLOR CONVERSION ROUTINES!!! I know we were discussing this awhile back when the new color palette was being built.		[[LittleCMS]] also has its own VERY ACCURATE COLOR CONVERSION ROUTINES!!! I know we were discussing this awhile back when the new color palette was being built.

			Note: adding some information on [[Adding color-profile element]]

	=== Implementation ===		=== Implementation ===

UyaEaw at 12:36, 18 April 2007

2007-04-18T12:36:11Z

← Older revision		Revision as of 12:36, 18 April 2007
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	Fill/stroke paints that mention an icc color reference a color-profile by name.		Fill/stroke paints that mention an icc color reference a color-profile by name.
	We thus need a mapping from name to color profile.		We thus need a mapping from name to color profile.
	This mapping is to be populated by handlers for the <color-profile> element and the <tt>@color-profile</tt> CSS at-rule. However, note that these handlers also need to cope with the user changing or deleting that element/stylesheet; and that there can be multiple purported definitions for a given name (in which case the last one wins). I think we want a doubly-linked list of definitions, and then we re-create the mapping (hashtable or whatever) in full when the list changes. (We don't expect the list to contain many entries, so it's cheap to rescan the whole list.) The <color-profile> element object should then include a pointer into that list, and I suppose that stylesheet objects should include multiple pointers into the list (given that stylesheets can contain arbitrarily many <tt>@color-profile</tt> at-rules). (The reason for storing a pointer rather than just storing the name is to allow for duplicate names in the list.)		This mapping is to be populated by handlers for the

	~~=== Links ===~~

	*[http://www.w3.org/TR/SVGPrint/#devcolor SVG Print mentions color issues], including expected color support in SVG 1.2

	~~[[Category:Developer Discussion]]~~

JonCruz: /* Implementation */

2007-03-28T18:18:52Z

Implementation

← Older revision		Revision as of 18:18, 28 March 2007
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	Of course our CSS infrastructure alone would need some radical changes before it would deal well with this well.		Of course our CSS infrastructure alone would need some radical changes before it would deal well with this well.
	:<i>What changes do you have in mind? Below are the changes I'm aware of, but these aren't particularly radical. --pjrm</i>		:<i>What changes do you have in mind? Below are the changes I'm aware of, but these aren't particularly radical. --pjrm</i>

			Other examples with more parts:

			fill="uri(#pat) #f0f icc-color(myprofile, .1, .3)"
			fill="steelblue icc-color(cmyk, 0.8, 0.1745, 0.098, 0.2)"
			fill="uri(#machine) steelblue icc-color(cmyk, 0.8, 0.1745, 0.098, 0.2)"

			SVG 1.2 had proposed additional icc-named-color and device-color:

			fill="steelblue icc-named-color(named, greyblue) device-color(spot-inks, blue7030)"

	==== SPIPaint ====		==== SPIPaint ====

GigaClon at 22:20, 20 June 2006

2006-06-20T22:20:09Z

← Older revision		Revision as of 22:20, 20 June 2006
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	*[http://www.w3.org/TR/SVGPrint/#devcolor SVG Print mentions color issues], including expected color support in SVG 1.2		*[http://www.w3.org/TR/SVGPrint/#devcolor SVG Print mentions color issues], including expected color support in SVG 1.2

	[[Category:~~User Documentation~~]]		[[Category:Developer Discussion]]