color space.htm

是一部关于java高级图像处理的的一本入门书

<P></P></LI></UL></PRE>
  <DL><A name=51488>
    <DT>
    <DD>transforms a color value assumed to be in the <CODE>CS_CIEXYZ</CODE> 
    conversion color space into this <CODE>ColorSpace</CODE>. </A>
    <P></P></DD></DL><PRE><UL>
<LI>static ColorSpace getInstance(int colorspace)
<P></P></LI></UL></PRE>
  <DL><A name=51497>
    <DT>
    <DD>returns a ColorSpace representing one of the specific predefined color 
    spaces.
    <P>
    <TABLE cellPadding=3 border=3>
      <CAPTION><FONT size=-1><B></B></FONT></CAPTION>
      <TBODY>
      <TR vAlign=top>
        <TD><EM>Parameter</EM>:<EM></EM> 
          <P></P>
        <TD><CODE>colorSpace</CODE> 
          <P></P>
        <TD>A specific color space identified by one of the predefined class 
          constants (e.g., <CODE>CS_sRGB</CODE>, <CODE>CS_LINEAR_RGB</CODE>, 
          <CODE>CS_CIEXYZ</CODE>, <CODE>CS_GRAY</CODE>, or 
          <CODE>CS_PYCC</CODE>). 
          <P></P></TR></TBODY></TABLE></A>
    <P></P></DD></DL><PRE><UL>
<LI>int getType()
<P></P></LI></UL></PRE>
  <DL><A name=51499>
    <DT>
    <DD>returns the color space type of this <CODE>ColorSpace</CODE> (for 
    example <CODE>TYPE_RGB</CODE>, <CODE>TYPE_XYZ</CODE>, etc.). </A>
    <P></P></DD></DL><A name=51500>
  <H3>5.2.3 <IMG src="Color Space.files/space.gif">ICC Profile and ICC Color 
  Space</H3></A>The <CODE>ColorSpace</CODE> class is an abstract class. It is 
  expected that particular implementations of subclasses of 
  <CODE>ColorSpace</CODE> will support high performance conversion based on 
  underlying platform color management systems. The <CODE>ICC_ColorSpace</CODE> 
  class is one such implementation provided in the base AWT. Developers can 
  define their own subclasses to represent arbitrary color spaces, as long as 
  the appropriate "to" and "from" conversion methods are implemented. However, 
  most developers can simply use the default <CODE>sRGB</CODE> color space or 
  color spaces that are represented by commonly-available ICC profiles, such as 
  profiles for monitors and printers or profiles embedded in image 
  data.<CODE></CODE> 
  <P>The <CODE>ICC_ColorSpace</CODE> class is based on ICC profile data as 
  represented by the <CODE>ICC_Profile</CODE> class. The 
  <CODE>ICC_Profile</CODE> class is a representation of color profile data for 
  device-independent and device-dependent color spaces based on the <EM>ICC 
  Profile Format Specification</EM>, Version 3.4, August 15, 1997, from the 
  International Color Consortium. ICC profiles describe an <EM>input space</EM> 
  and a <EM>connection space</EM>, and define how to map between them. 
  <P>The <CODE>ICC_Profile</CODE> class has two subclasses that correspond to 
  the specific color types: 
  <P>
  <UL>
    <LI><CODE>ICC_ProfileRGB</CODE>, which represents <CODE>TYPE_RGB</CODE> 
    color spaces
    <P></P></LI></UL>
  <UL>
    <LI><CODE>ICC_ProfileGray</CODE>, which represents <CODE>TYPE_GRAY</CODE> 
    color spaces
    <P></P></LI></UL><A name=51516>
  <H2>5.3 <IMG src="Color Space.files/space.gif">Transparency</H2></A>Just as 
  images can have color, they can also have transparency. Transparency defines 
  the specular transmission of light through transparent materials, such as 
  glass, or the lack of transparency for completely opaque objects. The amount 
  of transparency is specified by an alpha (<IMG 
  src="Color Space.files/alpha.gif">) value. An alpha value of 0.0 specifies 
  complete translucency; an alpha value of 1.0 specifies complete opacity. 
  <P>Images can carry transparency information, known as the alpha channel, for 
  each pixel in the image. The alpha value is particularly important when colors 
  overlap. The alpha value specifies how much of the previously-rendered color 
  should show through. 
  <P>The Java <CODE>Transparency</CODE> interface defines the common 
  transparency modes for implementing classes. <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Color.doc.html#51528">Table 
  5-2</A> lists the variables used to specify transparency.
  <P>
  <TABLE cellPadding=3 border=3>
    <CAPTION><FONT size=-1><B><A name=51528><I>Table 5-2 </I><IMG 
    src="Color Space.files/sm-blank.gif" border=0> Transparency 
    </A></B></FONT></CAPTION>
    <TBODY>
    <TR vAlign=top>
      <TH><A name=51532>Name </A>
      <TH><A name=51534>Description </A>
    <TR vAlign=top>
      <TD><A name=51537>BITMASK</A><BR>
      <TD><A name=51539>Represents image data that is guaranteed to be either 
        completely opaque, with an alpha value of 1.0, or completely 
        transparent, with an alpha value of 0.0.</A><BR>
    <TR vAlign=top>
      <TD><A name=51542>OPAQUE</A><BR>
      <TD><A name=51544>Represents image data that is guaranteed to be 
        completely opaque, meaning that all pixels have an alpha value of 
        1.0.</A><BR>
    <TR vAlign=top>
      <TD><A name=51547>TRANSLUCENT</A><BR>
      <TD><A name=51549>Represents image data that contains or might contain 
        arbitrary alpha values between and including 0.0 and 
    1.0.</A><BR></TR></TBODY></TABLE>
  <P>Transparency is specified as part of the color model (see <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Color.doc.html#51226">Section 
  5.2.1, "Color Models</A>"). 
  <P><A name=51551>
  <H2>5.4 <IMG src="Color Space.files/space.gif">Color Conversion</H2></A>The 
  <CODE>ColorConvert</CODE> operation performs a pixel-by-pixel color conversion 
  of the data in a rendered or renderable source image. The data are treated as 
  having no alpha channel, i.e., all bands are color bands. The color space of 
  the source image is specified by the <CODE>ColorSpace</CODE> object of the 
  source image <CODE>ColorModel</CODE> which must not be null. 
  <P>JAI does not attempt to verify that the <CODE>ColorModel</CODE> of the 
  destination image is consistent with the <CODE>ColorSpace</CODE> parameter. To 
  ensure that this is the case, a compatible <CODE>ColorModel</CODE> must be 
  provided via an <CODE>ImageLayout</CODE> in the <CODE>RenderingHints</CODE> 
  (see <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Programming-environ.doc.html#55991">Section 
  3.7.3, "Rendering Hints</A>"). 
  <P>Integral data are assumed to occupy the full range of the respective data 
  type; floating point data are assumed to be normalized to the range [0.0,1.0]. 
  By default, the destination image bounds, data type, and number of bands are 
  the same as those of the source image. 
  <P>The <CODE>ColorConvert</CODE> operation takes one parameter:
  <P>
  <TABLE cellPadding=3 border=3>
    <CAPTION><FONT size=-1><B></B></FONT></CAPTION>
    <TBODY>
    <TR vAlign=top>
      <TH><A name=51557>Parameters </A>
      <TH><A name=51559>Type </A>
      <TH><A name=51561>Description </A>
    <TR vAlign=top>
      <TD><A name=51563>colorSpace</A><BR>
      <TD><A name=51565>ColorSpace</A><BR>
      <TD><A name=51567>The destination color space.</A><BR></TR></TBODY></TABLE>
  <P>For information on color space, see <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Color.doc.html#51305">Section 
  5.2.2, "Color Space</A>." 
  <P><A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Color.doc.html#51792">Listing 
  5-1</A> shows a code sample for a <CODE>ColorConvert</CODE> operation.
  <P><CAPTION><FONT size=-1><B><A name=51792>
  <CENTER><FONT size=-1><B><I>Listing 5-1 </I><IMG 
  src="Color Space.files/sm-blank.gif" border=0> Example ColorConvert 
  Operation</B></FONT></CENTER></A>
  <P></B></FONT></CAPTION>
  <HR>
  <TR valign="top"><TD><PRE>     // Read the image from the specified file name.
     RenderedOp src = JAI.create("fileload", fileName);
</PRE><TR valign="top"><TD><PRE>     // Create the ParameterBlock.
     ParameterBlock pb = new ParameterBlock();
     pb.addSource(src).add(colorSpace);
</PRE><TR valign="top"><TD><PRE>     // Perform the color conversion.
     RenderedOp dst = JAI.create("ColorConvert", pb);
</PRE>
  <HR>

  <P><A name=51591>
  <H2>5.5 <IMG src="Color Space.files/space.gif">Non-standard Linear Color 
  Conversion (BandCombine)</H2></A>In JAI, the <CODE>BandCombine</CODE> 
  operation performs a linear color conversion between color spaces other than 
  those listed in <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Color.doc.html#51319">Table 
  5-1</A>. The <CODE>BandCombine</CODE> operation computes a set of arbitrary 
  linear combinations of the bands of a rendered or renderable source image, 
  using a specified matrix. The matrix must have dimension (# of source bands 
  plus one) by (# of desired destination bands). 
  <P>The <CODE>BandCombine</CODE> operation takes one parameter:
  <P>
  <TABLE cellPadding=3 border=3>
    <CAPTION><FONT size=-1><B></B></FONT></CAPTION>
    <TBODY>
    <TR vAlign=top>
      <TH><A name=51599>Parameter </A>
      <TH><A name=51601>Type </A>
      <TH><A name=51603>Description </A>
    <TR vAlign=top>
      <TD><A name=51605>matrix</A><BR>
      <TD><A name=51607>double</A><BR>
      <TD><A name=51609>The matrix specifying the band 
    combination.</A><BR></TR></TBODY></TABLE>
  <P>As an example, assume the three-band source image and the matrix shown in 
  <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Color.doc.html#51639">Figure 
  5-1</A>. The equation to calculate the value of the destination pixel in this 
  example would be: 
  <P>
  <DL><A name=51615>
    <DT>
    <DD><EM>dst</EM> = (255 * 0.25) + (157 * 0.5) + (28 * 0.75) </A>
    <P><A name=51637>
    <HR>

    <CENTER><IMG src="Color Space.files/Color.doc.anc.gif"></CENTER>
    <HR>
    </A></DD></DL><A name=51639>
  <CENTER><FONT size=-1><B><I>Figure 5-1 </I><IMG 
  src="Color Space.files/sm-blank.gif" border=0> Band Combine 
  Example</B></FONT></CENTER></A>
  <P>In this example, the number of columns in the matrix is equal to the number 
  of bands in the source image. The number of rows in the matrix must equal the 
  number of bands in the destination image. For a destination image with three 
  bands, the values in the second row of the matrix would be used to calculate 
  the values in the second band of the destination image and the values in the 
  third row would be used to calculate the values in the third band. 
  <P>If the result of the computation underflows or overflows the minimum or 
  maximum value supported by the destination image, it will be clamped to the 
  minimum or maximum value, respectively. 
  <P><A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Color.doc.html#51816">Listing 
  5-2</A> shows a code sample for a <CODE>BandCombine</CODE> operation.
  <P><CAPTION><FONT size=-1><B><A name=51816>
  <CENTER><FONT size=-1><B><I>Listing 5-2 </I><IMG 
  src="Color Space.files/sm-blank.gif" border=0> Example BandCombine 
  Operation</B></FONT></CENTER></A>
  <P></B></FONT></CAPTION>
  <HR>
  <TR valign="top"><TD><PRE>     // Create the matrix.
     // Invert center band.
          double[][] matrix = {
                     { 1.0D,  0.0D, 0.0D,   0.0D },
                     { 0.0D, -1.0D, 0.0D, 255.0D },
                     { 0.0D,  0.0D, 1.0D,   0.0D },
                  };
</PRE><TR valign="top"><TD><PRE>     // Identity.
          double[][] matrix = {
                     { 1.0D, 0.0D, 0.0D, 0.0D },
                     { 0.0D, 1.0D, 0.0D, 0.0D },
                     { 0.0D, 0.0D, 1.0D, 0.0D },
                  };
</PRE><TR valign="top"><TD><PRE>     // Luminance stored into red band (3 band).
           double[][] matrix = {
                      { .114D, 0.587D, 0.299D, 0.0D },
                      { .000D, 0.000D, 0.000D, 0.0D },
                      { .000D, 0.000D, 0.000D, 0.0D }
                   };
</PRE><TR valign="top"><TD><PRE>     // Luminance (single band output).
           double[][] matrix = {
                      { .114D, 0.587D, 0.299D, 0.0D }
                   };
</PRE><TR valign="top"><TD><PRE>     // Create the ParameterBlock.
     ParameterBlock pb = new ParameterBlock();
     pb.addSource(src_image);
     pb.add(matrix);
</PRE><TR valign="top"><TD><PRE>     // Perform the band combine operation.
     dst = (PlanarImage)JAI.create("bandcombine", pb, null);
</PRE>
  <HR>

  <P>
  <P>
  <HR>
  <BR>
  <CENTER><A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/JAITOC.fm.html"><IMG 
  alt=Contents src="Color Space.files/contents.gif"></A> <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Acquisition.doc.html"><IMG 
  alt=Previous src="Color Space.files/previous.gif"></A> <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Image-manipulation.doc.html"><IMG 
  alt=Next src="Color Space.files/next.gif"></A> 
  <P><FONT size=5><I>Programming in Java Advanced Imaging</I></FONT> 
  </CENTER><BR>
  <H5><A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/copyright.html">Copyright</A> 
  &copy; 1999, Sun Microsystems, Inc. All rights reserved.</H5><!-- Last updated: Tue Nov 02 17:30:41 1999 --></BLOCKQUOTE>
<SCRIPT language=JavaScript src="Color Space.files/s_code_remote.js"></SCRIPT>
</BODY></HTML>