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public
abstract
class
ColorSpace
extends Object
java.lang.Object | |
↳ | android.graphics.ColorSpace |
A ColorSpace
is used to identify a specific organization of colors.
Each color space is characterized by a Model
that defines
how a color value is represented (for instance the Model#RGB
color
model defines a color value as a triplet of numbers).
Each component of a color must fall within a valid range, specific to each
color space, defined by getMinValue(int)
and getMaxValue(int)
This range is commonly \([0..1]\). While it is recommended to use values in the
valid range, a color space always clamps input and output values when performing
operations such as converting to a different color space.
This implementation provides a pre-defined set of common color spaces
described in the Named
enum. To obtain an instance of one of the
pre-defined color spaces, simply invoke get(android.graphics.ColorSpace.Named)
:
ColorSpace sRgb = ColorSpace.get(ColorSpace.Named.SRGB);
The get(android.graphics.ColorSpace.Named)
method always returns the same instance for a given
name. Color spaces with an Model#RGB
color model can be safely
cast to Rgb
. Doing so gives you access to more APIs to query various
properties of RGB color models: color gamut primaries, transfer functions,
conversions to and from linear space, etc. Please refer to Rgb
for
more information.
The documentation of Named
provides a detailed description of the
various characteristics of each available color space.
To allow conversion between color spaces, this implementation uses the CIE
XYZ profile connection space (PCS). Color values can be converted to and from
this PCS using toXyz(float[])
and fromXyz(float[])
.
For color space with a non-RGB color model, the white point of the PCS
must be the CIE standard illuminant D50. RGB color spaces use their
native white point (D65 for Named#SRGB
for instance and must
undergo Adaptation
as necessary.
Since the white point of the PCS is not defined for RGB color space, it is
highly recommended to use the variants of the connect(android.graphics.ColorSpace, android.graphics.ColorSpace)
method to perform conversions between color spaces. A color space can be
manually adapted to a specific white point using adapt(android.graphics.ColorSpace, float[])
.
Please refer to the documentation of Rgb
for more
information. Several common CIE standard illuminants are provided in this
class as reference (see ILLUMINANT_D65
or ILLUMINANT_D50
for instance).
Here is an example of how to convert from a color space to another:
// Convert from DCI-P3 to Rec.2020 ColorSpace.Connector connector = ColorSpace.connect( ColorSpace.get(ColorSpace.Named.DCI_P3), ColorSpace.get(ColorSpace.Named.BT2020)); float[] bt2020 = connector.transform(p3r, p3g, p3b);
You can easily convert to Named#SRGB
by omitting the second
parameter:
// Convert from DCI-P3 to sRGB ColorSpace.Connector connector = ColorSpace.connect(ColorSpace.get(ColorSpace.Named.DCI_P3)); float[] sRGB = connector.transform(p3r, p3g, p3b);
Conversions also work between color spaces with different color models:
// Convert from CIE L*a*b* (color model Lab) to Rec.709 (color model RGB) ColorSpace.Connector connector = ColorSpace.connect( ColorSpace.get(ColorSpace.Named.CIE_LAB), ColorSpace.get(ColorSpace.Named.BT709));
Color spaces and other related classes (Connector
for instance)
are immutable and stateless. They can be safely used from multiple concurrent
threads.
Public static methods provided by this class, such as get(android.graphics.ColorSpace.Named)
and connect(android.graphics.ColorSpace, android.graphics.ColorSpace)
, are also guaranteed to be
thread-safe.
Nested classes | |
---|---|
enum |
ColorSpace.Adaptation
List of adaptation matrices that can be used for chromatic adaptation using the von Kries transform. |
class |
ColorSpace.Connector
A connector transforms colors from a source color space to a destination color space. |
enum |
ColorSpace.Model
A color model is required by a |
enum |
ColorSpace.Named
List of common, named color spaces. |
enum |
ColorSpace.RenderIntent
A render intent determines how a |
class |
ColorSpace.Rgb
An RGB color space is an additive color space using the
|
Constants | |
---|---|
int |
MAX_ID
The maximum ID value a color space can have. |
int |
MIN_ID
The minimum ID value a color space can have. |
Fields | |
---|---|
public
static
final
float[] |
ILLUMINANT_A
Standard CIE 1931 2° illuminant A, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_B
Standard CIE 1931 2° illuminant B, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_C
Standard CIE 1931 2° illuminant C, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_D50
Standard CIE 1931 2° illuminant D50, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_D55
Standard CIE 1931 2° illuminant D55, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_D60
Standard CIE 1931 2° illuminant D60, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_D65
Standard CIE 1931 2° illuminant D65, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_D75
Standard CIE 1931 2° illuminant D75, encoded in xyY. |
public
static
final
float[] |
ILLUMINANT_E
Standard CIE 1931 2° illuminant E, encoded in xyY. |
Public methods | |
---|---|
static
ColorSpace
|
adapt(ColorSpace colorSpace, float[] whitePoint, ColorSpace.Adaptation adaptation)
Performs the chromatic adaptation of a color space from its native white point to the specified white point. |
static
ColorSpace
|
adapt(ColorSpace colorSpace, float[] whitePoint)
Performs the chromatic adaptation of a color space from its native white point to the specified white point. |
static
ColorSpace.Connector
|
connect(ColorSpace source, ColorSpace.RenderIntent intent)
Connects the specified color spaces to sRGB. |
static
ColorSpace.Connector
|
connect(ColorSpace source, ColorSpace destination, ColorSpace.RenderIntent intent)
Connects two color spaces to allow conversion from the source color space to the destination color space. |
static
ColorSpace.Connector
|
connect(ColorSpace source)
Connects the specified color spaces to sRGB. |
static
ColorSpace.Connector
|
connect(ColorSpace source, ColorSpace destination)
Connects two color spaces to allow conversion from the source color space to the destination color space. |
boolean
|
equals(Object o)
Indicates whether some other object is "equal to" this one. |
float[]
|
fromXyz(float x, float y, float z)
Converts tristimulus values from the CIE XYZ space to this color space's color model. |
abstract
float[]
|
fromXyz(float[] v)
Converts tristimulus values from the CIE XYZ space to this color space's color model. |
static
ColorSpace
|
get(ColorSpace.Named name)
Returns an instance of |
int
|
getComponentCount()
Returns the number of components that form a color value according to this color space's color model. |
int
|
getId()
Returns the ID of this color space. |
abstract
float
|
getMaxValue(int component)
Returns the maximum valid value for the specified component of this color space's color model. |
abstract
float
|
getMinValue(int component)
Returns the minimum valid value for the specified component of this color space's color model. |
ColorSpace.Model
|
getModel()
Return the color model of this color space. |
String
|
getName()
Returns the name of this color space. |
int
|
hashCode()
Returns a hash code value for the object. |
boolean
|
isSrgb()
Indicates whether this color space is the sRGB color space or equivalent to the sRGB color space. |
abstract
boolean
|
isWideGamut()
Returns whether this color space is a wide-gamut color space. |
static
ColorSpace
|
match(float[] toXYZD50, ColorSpace.Rgb.TransferParameters function)
Returns a |
String
|
toString()
Returns a string representation of the object. |
float[]
|
toXyz(float r, float g, float b)
Converts a color value from this color space's model to tristimulus CIE XYZ values. |
abstract
float[]
|
toXyz(float[] v)
Converts a color value from this color space's model to tristimulus CIE XYZ values. |
Inherited methods | |
---|---|
public static final int MAX_ID
The maximum ID value a color space can have.
See also:
Constant Value: 63 (0x0000003f)
public static final int MIN_ID
The minimum ID value a color space can have.
See also:
Constant Value: -1 (0xffffffff)
public static final float[] ILLUMINANT_A
Standard CIE 1931 2° illuminant A, encoded in xyY. This illuminant has a color temperature of 2856K.
public static final float[] ILLUMINANT_B
Standard CIE 1931 2° illuminant B, encoded in xyY. This illuminant has a color temperature of 4874K.
public static final float[] ILLUMINANT_C
Standard CIE 1931 2° illuminant C, encoded in xyY. This illuminant has a color temperature of 6774K.
public static final float[] ILLUMINANT_D50
Standard CIE 1931 2° illuminant D50, encoded in xyY. This illuminant has a color temperature of 5003K. This illuminant is used by the profile connection space in ICC profiles.
public static final float[] ILLUMINANT_D55
Standard CIE 1931 2° illuminant D55, encoded in xyY. This illuminant has a color temperature of 5503K.
public static final float[] ILLUMINANT_D60
Standard CIE 1931 2° illuminant D60, encoded in xyY. This illuminant has a color temperature of 6004K.
public static final float[] ILLUMINANT_D65
Standard CIE 1931 2° illuminant D65, encoded in xyY. This illuminant has a color temperature of 6504K. This illuminant is commonly used in RGB color spaces such as sRGB, BT.209, etc.
public static final float[] ILLUMINANT_D75
Standard CIE 1931 2° illuminant D75, encoded in xyY. This illuminant has a color temperature of 7504K.
public static final float[] ILLUMINANT_E
Standard CIE 1931 2° illuminant E, encoded in xyY. This illuminant has a color temperature of 5454K.
public static ColorSpace adapt (ColorSpace colorSpace, float[] whitePoint, ColorSpace.Adaptation adaptation)
Performs the chromatic adaptation of a color space from its native
white point to the specified white point. If the specified color space
does not have an Model#RGB
color model, or if the color
space already has the target white point, the color space is returned
unmodified.
The chromatic adaptation is performed using the von Kries method
described in the documentation of Adaptation
.
The color space returned by this method always has
an ID of MIN_ID
.
Parameters | |
---|---|
colorSpace |
ColorSpace : The color space to chromatically adapt
This value cannot be null . |
whitePoint |
float : The new white point
This value cannot be null . |
adaptation |
ColorSpace.Adaptation : The adaptation matrix
This value cannot be null . |
Returns | |
---|---|
ColorSpace |
A new color space if the specified color space has an RGB
model and a white point different from the specified white
point; the specified color space otherwise
This value cannot be null . |
public static ColorSpace adapt (ColorSpace colorSpace, float[] whitePoint)
Performs the chromatic adaptation of a color space from its native white point to the specified white point.
The chromatic adaptation is performed using the
Adaptation#BRADFORD
matrix.
The color space returned by this method always has
an ID of MIN_ID
.
Parameters | |
---|---|
colorSpace |
ColorSpace : The color space to chromatically adapt
This value cannot be null . |
whitePoint |
float : The new white point
This value cannot be null . |
Returns | |
---|---|
ColorSpace |
A ColorSpace instance with the same name, primaries,
transfer functions and range as the specified color space
This value cannot be null . |
public static ColorSpace.Connector connect (ColorSpace source, ColorSpace.RenderIntent intent)
Connects the specified color spaces to sRGB.
If the source color space does not use CIE XYZ D65 as its profile
connection space, the two spaces are chromatically adapted to use the
CIE standard illuminant D50
as needed.
If the source is the sRGB color space, an optimized connector is returned to avoid unnecessary computations and loss of precision.
Parameters | |
---|---|
source |
ColorSpace : The color space to convert colors from
This value cannot be null . |
intent |
ColorSpace.RenderIntent : The render intent to map colors from the source to the destination
This value cannot be null . |
Returns | |
---|---|
ColorSpace.Connector |
A non-null connector between the specified color space and sRGB |
public static ColorSpace.Connector connect (ColorSpace source, ColorSpace destination, ColorSpace.RenderIntent intent)
Connects two color spaces to allow conversion from the source color
space to the destination color space. If the source and destination
color spaces do not have the same profile connection space (CIE XYZ
with the same white point), they are chromatically adapted to use the
CIE standard illuminant D50
as needed.
If the source and destination are the same, an optimized connector is returned to avoid unnecessary computations and loss of precision.
Parameters | |
---|---|
source |
ColorSpace : The color space to convert colors from
This value cannot be null . |
destination |
ColorSpace : The color space to convert colors to
This value cannot be null . |
intent |
ColorSpace.RenderIntent : The render intent to map colors from the source to the destination
This value cannot be null . |
Returns | |
---|---|
ColorSpace.Connector |
A non-null connector between the two specified color spaces |
public static ColorSpace.Connector connect (ColorSpace source)
Connects the specified color spaces to sRGB.
If the source color space does not use CIE XYZ D65 as its profile
connection space, the two spaces are chromatically adapted to use the
CIE standard illuminant D50
as needed.
If the source is the sRGB color space, an optimized connector is returned to avoid unnecessary computations and loss of precision.
Colors are mapped from the source color space to the destination color
space using the RenderIntent#PERCEPTUAL
render intent.
Parameters | |
---|---|
source |
ColorSpace : The color space to convert colors from
This value cannot be null . |
Returns | |
---|---|
ColorSpace.Connector |
A non-null connector between the specified color space and sRGB |
public static ColorSpace.Connector connect (ColorSpace source, ColorSpace destination)
Connects two color spaces to allow conversion from the source color
space to the destination color space. If the source and destination
color spaces do not have the same profile connection space (CIE XYZ
with the same white point), they are chromatically adapted to use the
CIE standard illuminant D50
as needed.
If the source and destination are the same, an optimized connector is returned to avoid unnecessary computations and loss of precision.
Colors are mapped from the source color space to the destination color
space using the RenderIntent#PERCEPTUAL
render intent.
Parameters | |
---|---|
source |
ColorSpace : The color space to convert colors from
This value cannot be null . |
destination |
ColorSpace : The color space to convert colors to
This value cannot be null . |
Returns | |
---|---|
ColorSpace.Connector |
A non-null connector between the two specified color spaces |
public boolean equals (Object o)
Indicates whether some other object is "equal to" this one.
The equals
method implements an equivalence relation
on non-null object references:
x
, x.equals(x)
should return
true
.
x
and y
, x.equals(y)
should return true
if and only if
y.equals(x)
returns true
.
x
, y
, and z
, if
x.equals(y)
returns true
and
y.equals(z)
returns true
, then
x.equals(z)
should return true
.
x
and y
, multiple invocations of
x.equals(y)
consistently return true
or consistently return false
, provided no
information used in equals
comparisons on the
objects is modified.
x
,
x.equals(null)
should return false
.
The equals
method for class Object
implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x
and
y
, this method returns true
if and only
if x
and y
refer to the same object
(x == y
has the value true
).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the
general contract for the hashCode
method, which states
that equal objects must have equal hash codes.
Parameters | |
---|---|
o |
Object : the reference object with which to compare. |
Returns | |
---|---|
boolean |
true if this object is the same as the obj
argument; false otherwise. |
public float[] fromXyz (float x, float y, float z)
Converts tristimulus values from the CIE XYZ space to this color space's color model.
Parameters | |
---|---|
x |
float : The X component of the color value |
y |
float : The Y component of the color value |
z |
float : The Z component of the color value |
Returns | |
---|---|
float[] |
A new array whose size is equal to the number of color
components as returned by Model#getComponentCount()
This value cannot be null . |
public abstract float[] fromXyz (float[] v)
Converts tristimulus values from the CIE XYZ space to this color space's color model. The resulting value is passed back in the specified array.
The specified array's length must be at least equal to
to the number of color components as returned by
Model#getComponentCount()
, and its first 3 values must
be the XYZ components to convert from.
Parameters | |
---|---|
v |
float : An array of color components containing the XYZ values
to convert from, and large enough to hold the number
of components of this color space's model
This value cannot be null . |
Returns | |
---|---|
float[] |
The array passed in parameter
This value cannot be null . |
public static ColorSpace get (ColorSpace.Named name)
Returns an instance of ColorSpace
identified by the specified
name. The list of names provided in the Named
enum gives access
to a variety of common RGB color spaces.
This method always returns the same instance for a given name.
This method is thread-safe.
Parameters | |
---|---|
name |
ColorSpace.Named : The name of the color space to get an instance of
This value cannot be null . |
Returns | |
---|---|
ColorSpace |
A non-null ColorSpace instance |
public int getComponentCount ()
Returns the number of components that form a color value according to this color space's color model.
Returns | |
---|---|
int |
An integer between 1 and 4 Value is between 1 and 4 inclusive |
See also:
public int getId ()
Returns the ID of this color space. Positive IDs match the color
spaces enumerated in Named
. A negative ID indicates a
color space created by calling one of the public constructors.
Returns | |
---|---|
int |
An integer between MIN_ID and MAX_ID
Value is between MIN_ID and MAX_ID inclusive |
public abstract float getMaxValue (int component)
Returns the maximum valid value for the specified component of this color space's color model.
Parameters | |
---|---|
component |
int : The index of the component
Value is between 0 and 3 inclusive |
Returns | |
---|---|
float |
A floating point value greater than getMinValue(int) |
public abstract float getMinValue (int component)
Returns the minimum valid value for the specified component of this color space's color model.
Parameters | |
---|---|
component |
int : The index of the component
Value is between 0 and 3 inclusive |
Returns | |
---|---|
float |
A floating point value less than getMaxValue(int) |
public ColorSpace.Model getModel ()
Return the color model of this color space.
Returns | |
---|---|
ColorSpace.Model |
A non-null Model |
See also:
public String getName ()
Returns the name of this color space. The name is never null and contains always at least 1 character.
Color space names are recommended to be unique but are not guaranteed to be. There is no defined format but the name usually falls in one of the following categories:
Named#CIE_LAB
.Named#SRGB
or
Named#ACES
.Because the format of color space names is not defined, it is not recommended to programmatically identify a color space by its name alone. Names can be used as a first approximation.
It is however perfectly acceptable to display color space names to users in a UI, or in debuggers and logs. When displaying a color space name to the user, it is recommended to add extra information to avoid ambiguities: color model, a representation of the color space's gamut, white point, etc.
Returns | |
---|---|
String |
A non-null String of length >= 1 |
public int hashCode ()
Returns a hash code value for the object. This method is
supported for the benefit of hash tables such as those provided by
HashMap
.
The general contract of hashCode
is:
hashCode
method
must consistently return the same integer, provided no information
used in equals
comparisons on the object is modified.
This integer need not remain consistent from one execution of an
application to another execution of the same application.
equals(Object)
method, then calling the hashCode
method on each of
the two objects must produce the same integer result.
equals(java.lang.Object)
method, then calling the hashCode
method on each of the
two objects must produce distinct integer results. However, the
programmer should be aware that producing distinct integer results
for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by
class Object
does return distinct integers for distinct
objects. (This is typically implemented by converting the internal
address of the object into an integer, but this implementation
technique is not required by the
Java™ programming language.)
Returns | |
---|---|
int |
a hash code value for this object. |
public boolean isSrgb ()
Indicates whether this color space is the sRGB color space or equivalent to the sRGB color space.
A color space is considered sRGB if it meets all the following conditions:
Model#RGB
.Named#SRGB
primaries.
D65
.
Named#SRGB
.This method always returns true for Named#SRGB
.
Returns | |
---|---|
boolean |
True if this color space is the sRGB color space (or a close approximation), false otherwise |
public abstract boolean isWideGamut ()
Returns whether this color space is a wide-gamut color space.
An RGB color space is wide-gamut if its gamut entirely contains
the Named#SRGB
gamut and if the area of its gamut is
90% of greater than the area of the Named#NTSC_1953
gamut.
Returns | |
---|---|
boolean |
True if this color space is a wide-gamut color space, false otherwise |
public static ColorSpace match (float[] toXYZD50, ColorSpace.Rgb.TransferParameters function)
Returns a Named
instance of ColorSpace
that matches
the specified RGB to CIE XYZ transform and transfer functions. If no
instance can be found, this method returns null.
The color transform matrix is assumed to target the CIE XYZ space
a D50
standard illuminant.
Parameters | |
---|---|
toXYZD50 |
float : 3x3 column-major transform matrix from RGB to the profile
connection space CIE XYZ as an array of 9 floats, cannot be null
This value cannot be null . |
function |
ColorSpace.Rgb.TransferParameters : Parameters for the transfer functions
This value cannot be null . |
Returns | |
---|---|
ColorSpace |
A non-null ColorSpace if a match is found, null otherwise |
public String toString ()
Returns a string representation of the object. This method returns a string equal to the value of:
getName() + "(id=" + getId() + ", model=" + getModel() + ")"
For instance, the string representation of the Named#SRGB
color space is equal to the following value:
sRGB IEC61966-2.1 (id=0, model=RGB)
Returns | |
---|---|
String |
A string representation of the object
This value cannot be null . |
public float[] toXyz (float r, float g, float b)
Converts a color value from this color space's model to
tristimulus CIE XYZ values. If the color model of this color
space is not Model#RGB
, it is assumed that the
target CIE XYZ space uses a D50
standard illuminant.
This method is a convenience for color spaces with a model
of 3 components (Model#RGB
or Model#LAB
for instance). With color spaces using fewer or more components,
use toXyz(float[])
instead
Parameters | |
---|---|
r |
float : The first component of the value to convert from (typically R in RGB) |
g |
float : The second component of the value to convert from (typically G in RGB) |
b |
float : The third component of the value to convert from (typically B in RGB) |
Returns | |
---|---|
float[] |
A new array of 3 floats, containing tristimulus XYZ values
This value cannot be null . |
public abstract float[] toXyz (float[] v)
Converts a color value from this color space's model to
tristimulus CIE XYZ values. If the color model of this color
space is not Model#RGB
, it is assumed that the
target CIE XYZ space uses a D50
standard illuminant.
The specified array's length must be at least
equal to to the number of color components as returned by
Model#getComponentCount()
.
Parameters | |
---|---|
v |
float : An array of color components containing the color space's
color value to convert to XYZ, and large enough to hold
the resulting tristimulus XYZ values
This value cannot be null . |
Returns | |
---|---|
float[] |
The array passed in parameter
This value cannot be null . |