Typically, a Color or ColorModel would be associated with an ICC Profile which is either an input, display, or output profile (see the ICC specification). There are other types of ICC Profiles, e.g. abstract profiles, device link profiles, and named color profiles, which do not contain information appropriate for representing the color space of a color, image, or device (see ICC_Profile). Attempting to create an ICC_ColorSpace object from an inappropriate ICC Profile is an error.
ICC Profiles represent transformations from the color space of the profile (e.g. a monitor) to a Profile Connection Space (PCS). Profiles of interest for tagging images or colors have a PCS which is one of the device independent spaces (one CIEXYZ space and two CIELab spaces) defined in the ICC Profile Format Specification. Most profiles of interest either have invertible transformations or explicitly specify transformations going both directions. Should an ICC_ColorSpace object be used in a way requiring a conversion from PCS to the profile's native space and there is inadequate data to correctly perform the conversion, the ICC_ColorSpace object will produce output in the specified type of color space (e.g. TYPE_RGB, TYPE_CMYK, etc.), but the specific color values of the output data will be undefined.
The details of this class are not important for simple applets, which draw in a default color space or manipulate and display imported images with a known color space. At most, such applets would need to get one of the default color spaces via ColorSpace.getInstance().
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.
This method transforms color values using relative colorimetry, as defined by the ICC Specification. This means that the XYZ argument values taken by this method are represented relative to the D50 white point of the CS_CIEXYZ color space. This representation is useful in a two-step color conversion process in which colors are transformed from an input color space to CS_CIEXYZ and then to an output color space. The color values returned by this method are not those that would produce the XYZ value passed to the method when measured by a colorimeter. If you have XYZ values corresponding to measurements made using current CIE recommended practices, they must be converted to D50 relative values before being passed to this method. The paragraphs below explain this in more detail.
The ICC standard uses a device independent color space (DICS) as the mechanism for converting color from one device to another device. In this architecture, colors are converted from the source device's color space to the ICC DICS and then from the ICC DICS to the destination device's color space. The ICC standard defines device profiles which contain transforms which will convert between a device's color space and the ICC DICS. The overall conversion of colors from a source device to colors of a destination device is done by connecting the device-to-DICS transform of the profile for the source device to the DICS-to-device transform of the profile for the destination device. For this reason, the ICC DICS is commonly referred to as the profile connection space (PCS). The color space used in the methods toCIEXYZ and fromCIEXYZ is the CIEXYZ PCS defined by the ICC Specification. This is also the color space represented by ColorSpace.CS_CIEXYZ.
The XYZ values of a color are often represented as relative to some white point, so the actual meaning of the XYZ values cannot be known without knowing the white point of those values. This is known as relative colorimetry. The PCS uses a white point of D50, so the XYZ values of the PCS are relative to D50. For example, white in the PCS will have the XYZ values of D50, which is defined to be X=.9642, Y=1.000, and Z=0.8249. This white point is commonly used for graphic arts applications, but others are often used in other applications.
To quantify the color characteristics of a device such as a printer or monitor, measurements of XYZ values for particular device colors are typically made. For purposes of this discussion, the term device XYZ values is used to mean the XYZ values that would be measured from device colors using current CIE recommended practices.
Converting between device XYZ values and the PCS XYZ values taken as arguments by this method corresponds to converting between the device's color space, as represented by CIE colorimetric values, and the PCS. There are many factors involved in this process, some of which are quite subtle. The most important, however, is the adjustment made to account for differences between the device's white point and the white point of the PCS. There are many techniques for doing this and it is the subject of much current research and controversy. Some commonly used methods are XYZ scaling, the von Kries transform, and the Bradford transform. The proper method to use depends upon each particular application.
The simplest method is XYZ scaling. In this method each device XYZ value is converted to a PCS XYZ value by multiplying it by the ratio of the PCS white point (D50) to the device white point.
Xd, Yd, Zd are the device XYZ values Xdw, Ydw, Zdw are the device XYZ white point values Xp, Yp, Zp are the PCS XYZ values Xd50, Yd50, Zd50 are the PCS XYZ white point values Xp = Xd * (Xd50 / Xdw) Yp = Yd * (Yd50 / Ydw) Zp = Zd * (Zd50 / Zdw)
Conversion from the PCS to the device would be done by inverting these equations:
Xd = Xp * (Xdw / Xd50) Yd = Yp * (Ydw / Yd50) Zd = Zp * (Zdw / Zd50)
Note that the media white point tag in an ICC profile is not the same as the device white point. The media white point tag is expressed in PCS values and is used to represent the difference between the XYZ of device illuminant and the XYZ of the device media when measured under that illuminant. The device white point is expressed as the device XYZ values corresponding to white displayed on the device. For example, displaying the RGB color (1.0, 1.0, 1.0) on an sRGB device will result in a measured device XYZ value of D65. This will not be the same as the media white point tag XYZ value in the ICC profile for an sRGB device.
This method transforms color values using algorithms designed
to produce the best perceptual match between input and output
colors. In order to do colorimetric conversion of color values,
you should use the toCIEXYZ
method of the CS_sRGB color space to first convert from the input
color space to the CS_CIEXYZ color space, and then use the
fromCIEXYZ method of this color space to
convert from CS_CIEXYZ to the output color space.
See toCIEXYZ
and
fromCIEXYZ
for further information.
java.util.Hashtable.
The general contract of hashCode is:
hashCode method on each of
the two objects must produce the same integer result.
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 JavaTM programming language.)
wait methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized statement
that synchronizes on the object.
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method transforms color values using relative colorimetry, as defined by the ICC Specification. This means that the XYZ values returned by this method are represented relative to the D50 white point of the CS_CIEXYZ color space. This representation is useful in a two-step color conversion process in which colors are transformed from an input color space to CS_CIEXYZ and then to an output color space. This representation is not the same as the XYZ values that would be measured from the given color value by a colorimeter. A further transformation is necessary to compute the XYZ values that would be measured using current CIE recommended practices. The paragraphs below explain this in more detail.
The ICC standard uses a device independent color space (DICS) as the mechanism for converting color from one device to another device. In this architecture, colors are converted from the source device's color space to the ICC DICS and then from the ICC DICS to the destination device's color space. The ICC standard defines device profiles which contain transforms which will convert between a device's color space and the ICC DICS. The overall conversion of colors from a source device to colors of a destination device is done by connecting the device-to-DICS transform of the profile for the source device to the DICS-to-device transform of the profile for the destination device. For this reason, the ICC DICS is commonly referred to as the profile connection space (PCS). The color space used in the methods toCIEXYZ and fromCIEXYZ is the CIEXYZ PCS defined by the ICC Specification. This is also the color space represented by ColorSpace.CS_CIEXYZ.
The XYZ values of a color are often represented as relative to some white point, so the actual meaning of the XYZ values cannot be known without knowing the white point of those values. This is known as relative colorimetry. The PCS uses a white point of D50, so the XYZ values of the PCS are relative to D50. For example, white in the PCS will have the XYZ values of D50, which is defined to be X=.9642, Y=1.000, and Z=0.8249. This white point is commonly used for graphic arts applications, but others are often used in other applications.
To quantify the color characteristics of a device such as a printer or monitor, measurements of XYZ values for particular device colors are typically made. For purposes of this discussion, the term device XYZ values is used to mean the XYZ values that would be measured from device colors using current CIE recommended practices.
Converting between device XYZ values and the PCS XYZ values returned by this method corresponds to converting between the device's color space, as represented by CIE colorimetric values, and the PCS. There are many factors involved in this process, some of which are quite subtle. The most important, however, is the adjustment made to account for differences between the device's white point and the white point of the PCS. There are many techniques for doing this and it is the subject of much current research and controversy. Some commonly used methods are XYZ scaling, the von Kries transform, and the Bradford transform. The proper method to use depends upon each particular application.
The simplest method is XYZ scaling. In this method each device XYZ value is converted to a PCS XYZ value by multiplying it by the ratio of the PCS white point (D50) to the device white point.
Xd, Yd, Zd are the device XYZ values Xdw, Ydw, Zdw are the device XYZ white point values Xp, Yp, Zp are the PCS XYZ values Xd50, Yd50, Zd50 are the PCS XYZ white point values Xp = Xd * (Xd50 / Xdw) Yp = Yd * (Yd50 / Ydw) Zp = Zd * (Zd50 / Zdw)
Conversion from the PCS to the device would be done by inverting these equations:
Xd = Xp * (Xdw / Xd50) Yd = Yp * (Ydw / Yd50) Zd = Zp * (Zdw / Zd50)
Note that the media white point tag in an ICC profile is not the same as the device white point. The media white point tag is expressed in PCS values and is used to represent the difference between the XYZ of device illuminant and the XYZ of the device media when measured under that illuminant. The device white point is expressed as the device XYZ values corresponding to white displayed on the device. For example, displaying the RGB color (1.0, 1.0, 1.0) on an sRGB device will result in a measured device XYZ value of D65. This will not be the same as the media white point tag XYZ value in the ICC profile for an sRGB device.
This method transforms color values using algorithms designed
to produce the best perceptual match between input and output
colors. In order to do colorimetric conversion of color values,
you should use the toCIEXYZ
method of this color space to first convert from the input
color space to the CS_CIEXYZ color space, and then use the
fromCIEXYZ method of the CS_sRGB color space to
convert from CS_CIEXYZ to the output color space.
See toCIEXYZ
and
fromCIEXYZ
for further information.
toString method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify method
or the notifyAll method.
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.