ColorSpace
abstract class ColorSpace
kotlin.Any | |
↳ | android.graphics.ColorSpace |
A ColorSpace
is used to identify a specific organization of colors. Each color space is characterized by a color model
that defines how a color value is represented (for instance the 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.
Using color spaces
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 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.
Color space conversions
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 sRGB
for instance and must undergo chromatic 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 color spaces
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 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 multi-threading
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.
Summary
Nested classes | |
---|---|
List of adaptation matrices that can be used for chromatic adaptation using the von Kries transform. |
|
open |
A connector transforms colors from a source color space to a destination color space. |
A color model is required by a |
|
List of common, named color spaces. |
|
A render intent determines how a |
|
open |
An RGB color space is an additive color space using the |
Constants | |
---|---|
static Int |
The maximum ID value a color space can have. |
static Int |
The minimum ID value a color space can have. |
Public methods | |
---|---|
open static ColorSpace |
adapt(colorSpace: ColorSpace, whitePoint: FloatArray) Performs the chromatic adaptation of a color space from its native white point to the specified white point. |
open static ColorSpace |
adapt(colorSpace: ColorSpace, whitePoint: FloatArray, adaptation: ColorSpace.Adaptation) Performs the chromatic adaptation of a color space from its native white point to the specified white point. |
open static FloatArray |
Computes the chromaticity coordinates of a specified correlated color temperature (CCT) on the Planckian locus. |
open static FloatArray |
chromaticAdaptation(adaptation: ColorSpace.Adaptation, srcWhitePoint: FloatArray, dstWhitePoint: FloatArray) Computes the chromatic adaptation transform from the specified source white point to the specified destination white point. |
open static ColorSpace.Connector |
connect(source: ColorSpace, destination: ColorSpace) Connects two color spaces to allow conversion from the source color space to the destination color space. |
open static ColorSpace.Connector |
connect(source: ColorSpace, destination: ColorSpace, intent: ColorSpace.RenderIntent) Connects two color spaces to allow conversion from the source color space to the destination color space. |
open static ColorSpace.Connector |
connect(source: ColorSpace) Connects the specified color spaces to sRGB. |
open static ColorSpace.Connector |
connect(source: ColorSpace, intent: ColorSpace.RenderIntent) Connects the specified color spaces to sRGB. |
open Boolean | |
open FloatArray |
Converts tristimulus values from the CIE XYZ space to this color space's color model. |
abstract FloatArray |
fromXyz(v: FloatArray) Converts tristimulus values from the CIE XYZ space to this color space's color model. |
open static ColorSpace |
get(name: ColorSpace.Named) Returns an instance of |
open Int |
Returns the number of components that form a color value according to this color space's color model. |
open Int |
Retrieve the |
open static ColorSpace? |
getFromDataSpace(dataSpace: Int) Create a |
open Int |
getId() Returns the ID of this color space. |
abstract Float |
getMaxValue(component: Int) Returns the maximum valid value for the specified component of this color space's color model. |
abstract Float |
getMinValue(component: Int) Returns the minimum valid value for the specified component of this color space's color model. |
open ColorSpace.Model |
getModel() Return the color model of this color space. |
open String |
getName() Returns the name of this color space. |
open Int |
hashCode() |
open Boolean |
isSrgb() Indicates whether this color space is the sRGB color space or equivalent to the sRGB color space. |
abstract Boolean |
Returns whether this color space is a wide-gamut color space. |
open static ColorSpace? |
match(toXYZD50: FloatArray, function: ColorSpace.Rgb.TransferParameters) Returns a |
open String |
toString() Returns a string representation of the object. |
open FloatArray |
Converts a color value from this color space's model to tristimulus CIE XYZ values. |
abstract FloatArray |
toXyz(v: FloatArray) Converts a color value from this color space's model to tristimulus CIE XYZ values. |
Properties | |
---|---|
static FloatArray! |
Standard CIE 1931 2° illuminant A, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant B, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant C, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant D50, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant D55, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant D60, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant D65, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant D75, encoded in xyY. |
static FloatArray! |
Standard CIE 1931 2° illuminant E, encoded in xyY. |
Constants
MAX_ID
static val MAX_ID: Int
The maximum ID value a color space can have.
Value: 63
See Also
MIN_ID
static val MIN_ID: Int
The minimum ID value a color space can have.
Value: -1
See Also
Public methods
adapt
open static fun adapt(
colorSpace: ColorSpace,
whitePoint: FloatArray
): ColorSpace
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 |
FloatArray: The new white point This value cannot be null . |
Return | |
---|---|
ColorSpace |
A ColorSpace instance with the same name, primaries, transfer functions and range as the specified color space This value cannot be null . |
adapt
open static fun adapt(
colorSpace: ColorSpace,
whitePoint: FloatArray,
adaptation: ColorSpace.Adaptation
): ColorSpace
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 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 |
FloatArray: The new white point This value cannot be null . |
adaptation |
ColorSpace.Adaptation: The adaptation matrix This value cannot be null . |
Return | |
---|---|
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 . |
cctToXyz
open static fun cctToXyz(cct: Int): FloatArray
Computes the chromaticity coordinates of a specified correlated color temperature (CCT) on the Planckian locus. The specified CCT must be greater than 0. A meaningful CCT range is [1667, 25000].
The transform is computed using the methods in Kang et al., Design of Advanced Color - Temperature Control System for HDTV Applications, Journal of Korean Physical Society 41, 865-871 (2002).
Parameters | |
---|---|
cct |
Int: The correlated color temperature, in Kelvin Value is 1 or greater |
Return | |
---|---|
FloatArray |
Corresponding XYZ values This value cannot be null . |
Exceptions | |
---|---|
java.lang.IllegalArgumentException |
If cct is invalid |
chromaticAdaptation
open static fun chromaticAdaptation(
adaptation: ColorSpace.Adaptation,
srcWhitePoint: FloatArray,
dstWhitePoint: FloatArray
): FloatArray
Computes the chromatic adaptation transform from the specified source white point to the specified destination white point.
The transform is computed using the von Kries method, described in more details in the documentation of Adaptation
. The Adaptation
enum provides different matrices that can be used to perform the adaptation.
Parameters | |
---|---|
adaptation |
ColorSpace.Adaptation: The adaptation method This value cannot be null . |
srcWhitePoint |
FloatArray: The white point to adapt from This value cannot be null . |
dstWhitePoint |
FloatArray: The white point to adapt to This value cannot be null . |
Return | |
---|---|
FloatArray |
A 3x3 matrix as a non-null array of 9 floats |
connect
open static fun connect(
source: ColorSpace,
destination: ColorSpace
): ColorSpace.Connector
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 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 . |
Return | |
---|---|
ColorSpace.Connector |
A non-null connector between the two specified color spaces |
connect
open static fun connect(
source: ColorSpace,
destination: ColorSpace,
intent: ColorSpace.RenderIntent
): ColorSpace.Connector
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 . |
Return | |
---|---|
ColorSpace.Connector |
A non-null connector between the two specified color spaces |
connect
open static fun connect(source: ColorSpace): ColorSpace.Connector
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 perceptual
render intent.
Parameters | |
---|---|
source |
ColorSpace: The color space to convert colors from This value cannot be null . |
Return | |
---|---|
ColorSpace.Connector |
A non-null connector between the specified color space and sRGB |
connect
open static fun connect(
source: ColorSpace,
intent: ColorSpace.RenderIntent
): ColorSpace.Connector
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 . |
Return | |
---|---|
ColorSpace.Connector |
A non-null connector between the specified color space and sRGB |
equals
open fun equals(other: Any?): Boolean
Parameters | |
---|---|
obj |
the reference object with which to compare. |
Return | |
---|---|
Boolean |
true if this object is the same as the obj argument; false otherwise. |
fromXyz
open fun fromXyz(
x: Float,
y: Float,
z: Float
): FloatArray
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 |
Return | |
---|---|
FloatArray |
A new array whose size is equal to the number of color components as returned by Model#getComponentCount() This value cannot be null . |
fromXyz
abstract fun fromXyz(v: FloatArray): FloatArray
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 |
FloatArray: 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 . |
Return | |
---|---|
FloatArray |
The array passed in parameter This value cannot be null . |
get
open static fun get(name: ColorSpace.Named): ColorSpace
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.
Note that in the Android W release and later, this can return the SRGB ColorSpace if theColorSpace.Named
parameter is not enabled in the corresponding release.
Parameters | |
---|---|
name |
ColorSpace.Named: The name of the color space to get an instance of This value cannot be null . |
Return | |
---|---|
ColorSpace |
A non-null ColorSpace instance. If the ColorSpace is not supported then the SRGB ColorSpace is returned. |
getComponentCount
open fun getComponentCount(): Int
Returns the number of components that form a color value according to this color space's color model.
Return | |
---|---|
Int |
An integer between 1 and 4 Value is between 1 and 4 inclusive |
getDataSpace
open fun getDataSpace(): Int
Retrieve the DataSpace
value from a ColorSpace
object.
If this ColorSpace
object has no matching dataSpace
value, DATASPACE_UNKNOWN
will return.
getFromDataSpace
open static fun getFromDataSpace(dataSpace: Int): ColorSpace?
Create a ColorSpace
object using a DataSpace
value.
This function maps from a dataspace to a Named
ColorSpace. If no Named
ColorSpace object matching the dataSpace
value can be created, null
will return.
Return | |
---|---|
ColorSpace? |
the ColorSpace object or null if no matching colorspace can be found. |
getId
open fun getId(): Int
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.
Return | |
---|---|
Int |
An integer between MIN_ID and MAX_ID Value is between MIN_ID and MAX_ID inclusive |
getMaxValue
abstract fun getMaxValue(component: Int): Float
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 |
Return | |
---|---|
Float |
A floating point value greater than getMinValue(int) |
getMinValue
abstract fun getMinValue(component: Int): Float
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 |
Return | |
---|---|
Float |
A floating point value less than getMaxValue(int) |
getModel
open fun getModel(): ColorSpace.Model
Return the color model of this color space.
Return | |
---|---|
ColorSpace.Model |
A non-null Model |
getName
open fun getName(): String
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:
- Generic names used to identify color spaces in non-RGB color models. For instance:
Generic L*a*b*
. - Names tied to a particular specification. For instance:
sRGB IEC61966-2.1
orSMPTE ST 2065-1:2012 ACES
. - Ad-hoc names, often generated procedurally or by the user during a calibration workflow. These names often contain the make and model of the display.
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.
Return | |
---|---|
String |
A non-null String of length >= 1 |
hashCode
open fun hashCode(): Int
Return | |
---|---|
Int |
a hash code value for this object. |
isSrgb
open fun isSrgb(): Boolean
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:
- Its color model is
Model#RGB
. - Its primaries are within 1e-3 of the true
sRGB
primaries. - Its white point is within 1e-3 of the CIE standard illuminant
D65
. - Its opto-electronic transfer function is not linear.
- Its electro-optical transfer function is not linear.
- Its transfer functions yield values within 1e-3 of
Named#SRGB
. - Its range is \([0..1]\).
This method always returns true for Named#SRGB
.
Return | |
---|---|
Boolean |
True if this color space is the sRGB color space (or a close approximation), false otherwise |
isWideGamut
abstract fun isWideGamut(): Boolean
Returns whether this color space is a wide-gamut color space. An RGB color space is wide-gamut if its gamut entirely contains the sRGB
gamut and if the area of its gamut is 90% of greater than the area of the NTSC
gamut.
Return | |
---|---|
Boolean |
True if this color space is a wide-gamut color space, false otherwise |
match
open static fun match(
toXYZD50: FloatArray,
function: ColorSpace.Rgb.TransferParameters
): ColorSpace?
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 |
FloatArray: 3x3 column-major transform matrix from RGB to the profile connection space CIE XYZ as an array of 9 floats, cannot be null |
function |
ColorSpace.Rgb.TransferParameters: Parameters for the transfer functions This value cannot be null . |
Return | |
---|---|
ColorSpace? |
A non-null ColorSpace if a match is found, null otherwise |
toString
open fun toString(): String
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 sRGB
color space is equal to the following value:
sRGB IEC61966-2.1 (id=0, model=RGB)
Return | |
---|---|
String |
A string representation of the object This value cannot be null . |
toXyz
open fun toXyz(
r: Float,
g: Float,
b: Float
): FloatArray
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 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 (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) |
Return | |
---|---|
FloatArray |
A new array of 3 floats, containing tristimulus XYZ values This value cannot be null . |
toXyz
abstract fun toXyz(v: FloatArray): FloatArray
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 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 |
FloatArray: 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 . |
Return | |
---|---|
FloatArray |
The array passed in parameter This value cannot be null . |
Properties
ILLUMINANT_A
static val ILLUMINANT_A: FloatArray!
Standard CIE 1931 2° illuminant A, encoded in xyY. This illuminant has a color temperature of 2856K.
ILLUMINANT_B
static val ILLUMINANT_B: FloatArray!
Standard CIE 1931 2° illuminant B, encoded in xyY. This illuminant has a color temperature of 4874K.
ILLUMINANT_C
static val ILLUMINANT_C: FloatArray!
Standard CIE 1931 2° illuminant C, encoded in xyY. This illuminant has a color temperature of 6774K.
ILLUMINANT_D50
static val ILLUMINANT_D50: FloatArray!
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.
ILLUMINANT_D55
static val ILLUMINANT_D55: FloatArray!
Standard CIE 1931 2° illuminant D55, encoded in xyY. This illuminant has a color temperature of 5503K.
ILLUMINANT_D60
static val ILLUMINANT_D60: FloatArray!
Standard CIE 1931 2° illuminant D60, encoded in xyY. This illuminant has a color temperature of 6004K.
ILLUMINANT_D65
static val ILLUMINANT_D65: FloatArray!
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.709, etc.
ILLUMINANT_D75
static val ILLUMINANT_D75: FloatArray!
Standard CIE 1931 2° illuminant D75, encoded in xyY. This illuminant has a color temperature of 7504K.
ILLUMINANT_E
static val ILLUMINANT_E: FloatArray!
Standard CIE 1931 2° illuminant E, encoded in xyY. This illuminant has a color temperature of 5454K.