class QColorSpace

The QColorSpace class provides a color space abstraction. More…

Synopsis

Methods

Static functions

Note

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Detailed Description

Color values can be interpreted in different ways, and based on the interpretation can live in different spaces. We call this color spaces.

QColorSpace provides access to creating several predefined color spaces and can generate QColorTransforms for converting colors from one color space to another.

QColorSpace can also represent color spaces defined by ICC profiles or embedded in images, that do not otherwise fit the predefined color spaces.

A color space can generally speaking be conceived as a combination of set of primary colors and a transfer function. The primaries defines the axes of the color space, and the transfer function how values are mapped on the axes. The primaries are for Rgb color spaces defined by three primary colors that represent exactly how red, green, and blue look in this particular color space, and a white color that represents where and how bright pure white is. For grayscale color spaces, only a single white primary is needed. The range of colors expressible by the primary colors is called the gamut, and a color space that can represent a wider range of colors is also known as a wide-gamut color space.

The transfer function or gamma curve determines how each component in the color space is encoded. These are used because human perception does not operate linearly, and the transfer functions try to ensure that colors will seem evenly spaced to human eyes.

class NamedColorSpace

Predefined color spaces.

Constant

Description

QColorSpace.SRgb

The sRGB color space, which Qt operates in by default. It is a close approximation of how most classic monitors operate, and a mode most software and hardware support. ICC registration of sRGB .

QColorSpace.SRgbLinear

The sRGB color space with linear gamma. Useful for gamma-corrected blending.

QColorSpace.AdobeRgb

The Adobe RGB color space is a classic wide-gamut color space, using a gamma of 2.2. ICC registration of Adobe RGB (1998)

QColorSpace.DisplayP3

A color-space using the primaries of DCI-P3, but with the whitepoint and transfer function of sRGB. Common in modern wide-gamut screens. ICC registration of DCI-P3

QColorSpace.ProPhotoRgb

The Pro Photo RGB color space, also known as ROMM RGB is a very wide gamut color space. ICC registration of ROMM RGB

QColorSpace.Bt2020

BT.2020, also known as Rec.2020 is a basic colorspace of HDR TVs. ICC registration of BT.2020

QColorSpace.Bt2100Pq

BT.2100(PQ), also known as Rec.2100 or HDR10 is an HDR encoding with the same primaries as Bt2020 but using the Perceptual Quantizer transfer function. ICC registration of BT.2100

QColorSpace.Bt2100Hlg

BT.2100 (HLG) is an HDR encoding with the same primaries as Bt2020 but using the Hybrid Log-Gamma transfer function.
class Primaries

Predefined sets of primary colors.

Constant

Description

QColorSpace.Primaries.Custom

The primaries are undefined or does not match any predefined sets.

QColorSpace.Primaries.SRgb

The sRGB primaries

QColorSpace.Primaries.AdobeRgb

The Adobe RGB primaries

QColorSpace.Primaries.DciP3D65

The DCI-P3 primaries with the D65 whitepoint

QColorSpace.Primaries.ProPhotoRgb

The ProPhoto RGB primaries with the D50 whitepoint

QColorSpace.Primaries.Bt2020

The BT.2020 primaries with a D65 whitepoint
class TransferFunction

Predefined transfer functions or gamma curves.

Constant

Description

QColorSpace.TransferFunction.Custom

The custom or null transfer function

QColorSpace.TransferFunction.Linear

The linear transfer functions

QColorSpace.TransferFunction.Gamma

A transfer function that is a real gamma curve based on the value of gamma()

QColorSpace.TransferFunction.SRgb

The sRGB transfer function, composed of linear and gamma parts

QColorSpace.TransferFunction.ProPhotoRgb

The ProPhoto RGB transfer function, composed of linear and gamma parts

QColorSpace.TransferFunction.Bt2020

The BT.2020 transfer function, composited of linear and gamma parts

QColorSpace.TransferFunction.St2084

The SMPTE ST 2084 transfer function, also known Perceptual Quantizer(PQ).

QColorSpace.TransferFunction.Hlg

The Hybrid log-gamma transfer function.
class TransformModel

Defines the processing model used for color space transforms.

Constant

Description

QColorSpace.TransformModel.ThreeComponentMatrix

The transform consist of a matrix calculated from primaries and set of transfer functions for each color channel. This is very fast and used by all predefined color spaces. Any color space on this form is reversible and always both valid sources and targets.

QColorSpace.TransformModel.ElementListProcessing

The transforms are one or two lists of processing elements that can do many things, each list only process either to the connection color space or from it. This is very flexible, but rather slow, and can only be set by reading ICC profiles (See fromIccProfile() ). Since the two lists are separate a color space on this form can be a valid source, but not necessarily also a valid target. When changing either primaries or transfer function on a color space on this type it will reset to an empty ThreeComponentMatrix form.

Added in version 6.8.

class ColorModel

Defines the color model used by the color space data.

Constant

Description

QColorSpace.ColorModel.Undefined

No color model

QColorSpace.ColorModel.Rgb

An RGB color model with red, green, and blue colors. Can apply to RGB and grayscale data.

QColorSpace.ColorModel.Gray

A gray scale color model. Can only apply to grayscale data.

QColorSpace.ColorModel.Cmyk

Can only represent color data defined with cyan, magenta, yellow, and black colors. In effect only QImage::Format_CMYK32. Note Cmyk color spaces will be ElementListProcessing .

Added in version 6.8.

__init__()

Creates a new colorspace object that represents an undefined and invalid colorspace.

__init__(namedColorSpace)
Parameters:

namedColorSpace – NamedColorSpace

Creates a new colorspace object that represents a namedColorSpace.

__init__(colorSpace)
Parameters:

colorSpace – QColorSpace

Creates a new colorspace object that represents a namedColorSpace.

__init__(primaries, transferFunctionTable)
Parameters:

  • primaries – Primaries

  • transferFunctionTable – .list of uint16_t

Creates a custom color space with the primaries gamut, using a custom transfer function described by transferFunctionTable.

The table should contain at least 2 values, and contain an monotonically increasing list of values from 0 to 65535.

__init__(primaries, gamma)
Parameters:

Creates a custom color space with the primaries primaries, using a gamma transfer function of gamma.

__init__(whitePoint, transferFunctionTable)
Parameters:

  • whitePoint – QPointF

  • transferFunctionTable – .list of uint16_t

Creates a custom grayscale color space with white point whitePoint, and using the custom transfer function described by transferFunctionTable.

__init__(primaries, transferFunction[, gamma=0.0f])
Parameters:

Creates a custom color space with the primaries primaries, using the transfer function transferFunction and optionally gamma.

__init__(whitePoint, transferFunction[, gamma=0.0f])
Parameters:

Creates a custom grayscale color space with the white point whitePoint, using the transfer function transferFunction and optionally gamma.

__init__(whitePoint, redPoint, greenPoint, bluePoint, transferFunctionTable)
Parameters:

Creates a custom color space with primaries based on the chromaticities of the primary colors whitePoint, redPoint, greenPoint and bluePoint, and using the custom transfer function described by transferFunctionTable.

__init__(whitePoint, redPoint, greenPoint, bluePoint, transferFunction[, gamma=0.0f])
Parameters:

Creates a custom colorspace with a primaries based on the chromaticities of the primary colors whitePoint, redPoint, greenPoint and bluePoint, and using the transfer function transferFunction and optionally gamma.

__init__(whitePoint, redPoint, greenPoint, bluePoint, redTransferFunctionTable, greenTransferFunctionTable, blueTransferFunctionTable)
Parameters:

  • whitePoint – QPointF

  • redPoint – QPointF

  • greenPoint – QPointF

  • bluePoint – QPointF

  • redTransferFunctionTable – .list of uint16_t

  • greenTransferFunctionTable – .list of uint16_t

  • blueTransferFunctionTable – .list of uint16_t

Creates a custom color space with primaries based on the chromaticities of the primary colors whitePoint, redPoint, greenPoint and bluePoint, and using the custom transfer functions described by redTransferFunctionTable, greenTransferFunctionTable, and blueTransferFunctionTable.

colorModel()
Return type:

ColorModel

Returns the color model this color space can represent

description()
Return type:

str

Returns the name or short description. If a description hasn’t been given in setDescription() , the original name of the profile is returned if the profile is unmodified, a guessed name is returned if the profile has been recognized as a known color space, otherwise an empty string is returned.

See also

setDescription()

static fromIccProfile(iccProfile)
Parameters:

iccProfile – QByteArray

Return type:

QColorSpace

Creates a QColorSpace from ICC profile iccProfile.

Note

Not all ICC profiles are supported. QColorSpace only supports RGB or Gray ICC profiles.

If the ICC profile is not supported an invalid QColorSpace is returned where you can still read the original ICC profile using iccProfile() .

See also

iccProfile()

gamma()
Return type:

float

Returns the gamma value of color spaces with TransferFunction::Gamma, an approximate gamma value for other predefined color spaces, or 0.0 if no approximate gamma is known.

iccProfile()
Return type:

QByteArray

Returns an ICC profile representing the color space.

If the color space was generated from an ICC profile, that profile is returned, otherwise one is generated.

Note

Even invalid color spaces may return the ICC profile if they were generated from one, to allow applications to implement wider support themselves.

See also

fromIccProfile()

isValid()
Return type:

bool

Returns true if the color space is valid. For a color space with TransformModel::ThreeComponentMatrix that means both primaries and transfer functions set, and implies isValidTarget() . For a color space with TransformModel::ElementListProcessing it means it has a valid source transform, to check if it also a valid target color space use isValidTarget() .

See also

isValidTarget()

isValidTarget()
Return type:

bool

Returns true if the color space is a valid target color space.

__ne__(colorSpace2)
Parameters:

colorSpace2 – QColorSpace

Return type:

bool

Returns true if colorspace colorSpace1 is not equal to colorspace colorSpace2; otherwise returns false

__eq__(colorSpace2)
Parameters:

colorSpace2 – QColorSpace

Return type:

bool

Returns true if colorspace colorSpace1 is equal to colorspace colorSpace2; otherwise returns false

primaries()
Return type:

Primaries

Returns the predefined primaries of the color space or primaries::Custom if it doesn’t match any of them.

See also

setPrimaries()

setDescription(description)
Parameters:

description – str

Sets the name or short description of the color space to description.

If set to empty description() will return original or guessed descriptions instead.

See also

description()

setPrimaries(primariesId)
Parameters:

primariesId – Primaries

Sets the primaries to those of the primariesId set.

See also

primaries()

setPrimaries(whitePoint, redPoint, greenPoint, bluePoint)
Parameters:

Set primaries to the chromaticities of whitePoint, redPoint, greenPoint and bluePoint.

See also

primaries()

setTransferFunction(transferFunctionTable)
Parameters:

transferFunctionTable – .list of uint16_t

Sets the transfer function to transferFunctionTable.

setTransferFunction(transferFunction[, gamma=0.0f])
Parameters:

Sets the transfer function to transferFunction and gamma.

setTransferFunctions(redTransferFunctionTable, greenTransferFunctionTable, blueTransferFunctionTable)
Parameters:

  • redTransferFunctionTable – .list of uint16_t

  • greenTransferFunctionTable – .list of uint16_t

  • blueTransferFunctionTable – .list of uint16_t

Sets the transfer functions to redTransferFunctionTable, greenTransferFunctionTable and blueTransferFunctionTable.

setWhitePoint(whitePoint)
Parameters:

whitePoint – QPointF

Sets the white point to used for this color space to whitePoint.

See also

whitePoint()

swap(colorSpace)
Parameters:

colorSpace – QColorSpace

Swaps color space other with this color space. This operation is very fast and never fails.

transferFunction()
Return type:

TransferFunction

Returns the predefined transfer function of the color space or TransferFunction::Custom if it doesn’t match any of them.

transformModel()
Return type:

TransformModel

Returns the transfrom processing model used for this color space.

transformationToColorSpace(colorspace)
Parameters:

colorspace – QColorSpace

Return type:

QColorTransform

Generates and returns a color space transformation from this color space to colorspace.

whitePoint()
Return type:

QPointF

Returns the white point used for this color space. Returns a null QPointF if not defined.

See also

setWhitePoint()

withTransferFunction(transferFunctionTable)
Parameters:

transferFunctionTable – .list of uint16_t

Return type:

QColorSpace

Returns a copy of this color space, except using the transfer function described by transferFunctionTable.

withTransferFunction(transferFunction[, gamma=0.0f])
Parameters:
Return type:

QColorSpace

Returns a copy of this color space, except using the transfer function transferFunction and gamma.

withTransferFunctions(redTransferFunctionTable, greenTransferFunctionTable, blueTransferFunctionTable)
Parameters:

  • redTransferFunctionTable – .list of uint16_t

  • greenTransferFunctionTable – .list of uint16_t

  • blueTransferFunctionTable – .list of uint16_t

Return type:

QColorSpace

Returns a copy of this color space, except using the transfer functions described by redTransferFunctionTable, greenTransferFunctionTable and blueTransferFunctionTable.