/// <summary>
/// Transforms a color value assumed to be in the default CS_sRGB
/// color space into this ColorSpace.
/// <para>
/// 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 <code>toCIEXYZ</code>
/// 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
/// <code>fromCIEXYZ</code> method of this color space to
/// convert from CS_CIEXYZ to the output color space.
/// See <seealso cref="#toCIEXYZ(float[]) toCIEXYZ"/> and
/// <seealso cref="#fromCIEXYZ(float[]) fromCIEXYZ"/> for further information.
/// </para>
/// <para>
/// </para>
/// </summary>
/// <param name="rgbvalue"> a float array with length of at least 3. </param>
/// <returns> a float array with length equal to the number of
/// components in this ColorSpace. </returns>
/// <exception cref="ArrayIndexOutOfBoundsException"> if array length is not
/// at least 3. </exception>
public override float[] FromRGB(float[] rgbvalue)
{
if (Srgb2this == null)
{
ColorTransform[] transformList = new ColorTransform [2];
ICC_ColorSpace srgbCS = (ICC_ColorSpace)ColorSpace.GetInstance(CS_sRGB_Renamed);
PCMM mdl = CMSManager.Module;
transformList[0] = mdl.createTransform(srgbCS.Profile, ColorTransform.Any, ColorTransform.In);
transformList[1] = mdl.createTransform(ThisProfile, ColorTransform.Any, ColorTransform.Out);
Srgb2this = mdl.createTransform(transformList);
if (NeedScaleInit)
{
SetComponentScaling();
}
}
short[] tmp = new short[3];
for (int i = 0; i < 3; i++)
{
tmp[i] = (short)((rgbvalue[i] * 65535.0f) + 0.5f);
}
tmp = Srgb2this.colorConvert(tmp, null);
int nc = this.NumComponents;
float[] result = new float [nc];
for (int i = 0; i < nc; i++)
{
result[i] = (((float)(tmp[i] & 0xffff)) / 65535.0f) * DiffMinMax[i] + MinVal[i];
}
return(result);
}
/// <summary>
/// Transforms a color value assumed to be in the CS_CIEXYZ conversion
/// color space into this ColorSpace.
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.
/// <pre>
///
/// 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)
///
/// </pre>
/// </para>
/// <para>
/// Conversion from the PCS to the device would be done by inverting these
/// equations:
/// <pre>
///
/// Xd = Xp * (Xdw / Xd50)
/// Yd = Yp * (Ydw / Yd50)
/// Zd = Zp * (Zdw / Zd50)
///
/// </pre>
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// </para>
/// </summary>
/// <param name="colorvalue"> a float array with length of at least 3. </param>
/// <returns> a float array with length equal to the number of
/// components in this ColorSpace. </returns>
/// <exception cref="ArrayIndexOutOfBoundsException"> if array length is not
/// at least 3. </exception>
public override float[] FromCIEXYZ(float[] colorvalue)
{
if (Xyz2this == null)
{
ColorTransform[] transformList = new ColorTransform [2];
ICC_ColorSpace xyzCS = (ICC_ColorSpace)ColorSpace.GetInstance(CS_CIEXYZ);
PCMM mdl = CMSManager.Module;
transformList[0] = mdl.createTransform(xyzCS.Profile, ColorTransform.Any, ColorTransform.In);
try
{
transformList[1] = mdl.createTransform(ThisProfile, ICC_Profile.IcRelativeColorimetric, ColorTransform.Out);
}
catch (CMMException)
{
transformList[1] = CMSManager.Module.createTransform(ThisProfile, ColorTransform.Any, ColorTransform.Out);
}
Xyz2this = mdl.createTransform(transformList);
if (NeedScaleInit)
{
SetComponentScaling();
}
}
short[] tmp = new short[3];
float ALMOST_TWO = 1.0f + (32767.0f / 32768.0f);
float factor = 65535.0f / ALMOST_TWO;
// For CIEXYZ, min = 0.0, max = ALMOST_TWO for all components
for (int i = 0; i < 3; i++)
{
tmp[i] = (short)((colorvalue[i] * factor) + 0.5f);
}
tmp = Xyz2this.colorConvert(tmp, null);
int nc = this.NumComponents;
float[] result = new float [nc];
for (int i = 0; i < nc; i++)
{
result[i] = (((float)(tmp[i] & 0xffff)) / 65535.0f) * DiffMinMax[i] + MinVal[i];
}
return(result);
}
