image enhancement.htm

是一部关于java高级图像处理的的一本入门书

      <CAPTION><FONT size=-1><B></B></FONT></CAPTION>
      <TBODY>
      <TR vAlign=top>
        <TH><A name=68880>Policy </A>
        <TH><A name=68882>Description </A>
      <TR vAlign=top>
        <TD><A name=68884>BORDER_ZERO</A><BR>
        <TD><A name=68886>Set sample values to zero.</A><BR>
      <TR vAlign=top>
        <TD><A name=68888>BORDER_COPY</A><BR>
        <TD><A name=68890>Set sample values to copies of the nearest valid 
          pixel. For example, pixels to the left of the valid rectangle will 
          take on the value of the valid edge pixel in the same row. Pixels both 
          above and to the left of the valid rectangle will take on the value of 
          the upper-left pixel.</A><BR>
      <TR vAlign=top>
        <TD><A name=68892>BORDER_REFLECT</A><BR>
        <TD><A name=68918>The output image is defined as if mirrors were 
          placed along the edges of the source image. Thus if the left edge of 
          the valid rectangle lies at <EM>x</EM> = 10, pixel (9, <EM>y</EM>) 
          will be a copy of pixel (10, <EM>y</EM>); pixel (6, <EM>y</EM>) will 
          be a copy of pixel (13, <EM>y</EM>).</A><BR>
      <TR vAlign=top>
        <TD><A name=68896>BORDER_WRAP</A><BR>
        <TD><A name=68938>The source image is tiled repeatedly in the 
          plane.</A><BR></TR></TBODY></TABLE></A>
    <P></P></DD></DL><PRE><UL>
<LI>abstract void extend(WritableRaster raster, PlanarImage im)
<P></P></LI></UL></PRE>
  <DL><A name=68781>
    <DT>
    <DD>fills in the portions of a given <CODE>Raster</CODE> that lie outside 
    the bounds of a given <CODE>PlanarImage</CODE> with data derived from that 
    <CODE>PlanarImage</CODE>. </A>
    <P></P></DD></DL><A name=72409>
  <H4>7.2.2.1 <IMG 
  src="Image Enhancement.files/space.gif">BorderExtenderZero</H4></A>The 
  <CODE>BorderExtenderZero</CODE> class is a subclass of 
  <CODE>BorderExtender</CODE> that implements border extension by filling all 
  pixels outside of the image bounds with zeros. For example, <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Image-enhance.doc.html#73911">Figure 
  7-2</A> shows the result of using <CODE>BorderExtenderZero</CODE> to extend an 
  image by adding two extra rows to the top and bottom and two extra columns on 
  the left and right sides. 
  <P><A name=73910>
  <HR>

  <CENTER><IMG 
  src="Image Enhancement.files/Image-enhance.doc.anc15.gif"></CENTER>
  <HR>
  </A><A name=73911>
  <CENTER><FONT size=-1><B><I>Figure 7-2 </I><IMG 
  src="Image Enhancement.files/sm-blank.gif" border=0> BorderExtenderZero 
  Example</B></FONT></CENTER></A>
  <P>
  <TABLE border=0>
    <TBODY>
    <TR>
      <TD><IMG src="Image Enhancement.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>javax.media.jai.BorderExtenderZero </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>final void extend(WritableRaster raster, PlanarImage im)
<P></P></LI></UL></PRE>
  <DL><A name=72720>
    <DT>
    <DD>fills in the portions of a given <CODE>Raster</CODE> that lie outside 
    the bounds of a given <CODE>PlanarImage</CODE> with zeros. The portion of 
    Raster that lies within <CODE>im.getBounds</CODE> is not altered. </A>
    <P></P></DD></DL><A name=72000>
  <H4>7.2.2.2 <IMG 
  src="Image Enhancement.files/space.gif">BorderExtenderConstant</H4></A>The 
  <CODE>BorderExtenderConstant</CODE> class is a subclass of 
  <CODE>BorderExtender</CODE> that implements border extension by filling all 
  pixels outside of the image bounds with constant values. For example, <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Image-enhance.doc.html#74089">Figure 
  7-3</A> shows the result of using <CODE>BorderExtenderConstant</CODE> to 
  extend an image by adding two extra rows to the top and bottom and two extra 
  columns on the left and right sides. 
  <P>In the figure, X is the constant fill value. The set of constants is 
  clamped to the range and precision of the data type of the <CODE>Raster</CODE> 
  being filled. The number of constants used is given by the number of bands of 
  the <CODE>Raster</CODE>. If the <CODE>Raster</CODE> has <EM>b</EM> bands, and 
  there are <EM>c</EM> constants, constants 0 through <EM>b</EM> - 1 are used 
  when <EM>b</EM> <IMG src="Image Enhancement.files/lt_equal.gif"> <EM>c</EM>. 
  If <EM>b</EM> &gt; <EM>c</EM>, zeros are used to fill out the constants array. 

  <P><A name=74088>
  <HR>

  <CENTER><IMG 
  src="Image Enhancement.files/Image-enhance.doc.anc14.gif"></CENTER>
  <HR>
  </A><A name=74089>
  <CENTER><FONT size=-1><B><I>Figure 7-3 </I><IMG 
  src="Image Enhancement.files/sm-blank.gif" border=0> BorderExtenderConstant 
  Example</B></FONT></CENTER></A>
  <P>
  <TABLE border=0>
    <TBODY>
    <TR>
      <TD><IMG src="Image Enhancement.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>javax.media.jai.BorderExtenderConstant </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>BorderExtenderConstant(double[] constants)
<P></P></LI></UL></PRE>
  <DL><A name=72359>
    <DT>
    <DD>constructs an instance of <CODE>BorderExtenderConstant</CODE> with a 
    given set of constants. The constants are specified as an array of 
    <CODE>double</CODE>s. </A>
    <P></P></DD></DL><PRE><UL>
<LI>final void extend(WritableRaster raster, PlanarImage im)
<P></P></LI></UL></PRE>
  <DL><A name=72379>
    <DT>
    <DD>fills in the portions of a given <CODE>Raster</CODE> that lie outside 
    the bounds of a given <CODE>PlanarImage</CODE> with constant values. The 
    portion of <CODE>Raster</CODE> that lies within <CODE>im.getBounds</CODE> is 
    not altered. </A>
    <P></P></DD></DL><A name=72770>
  <H4>7.2.2.3 <IMG 
  src="Image Enhancement.files/space.gif">BorderExtenderCopy</H4></A>The 
  <CODE>BorderExtenderCopy</CODE> class is a subclass of 
  <CODE>BorderExtender</CODE> that implements border extension by filling all 
  pixels outside of the image bounds with copies of the edge pixels. For 
  example, <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Image-enhance.doc.html#74281">Figure 
  7-4</A> shows the result of using <CODE>BorderExtenderCopy</CODE> to extend an 
  image by adding two extra rows to the top and bottom and two extra columns on 
  the left and right sides. 
  <P>Although this type of extension is not particularly visually appealing, it 
  is useful as a way of padding source images prior to area or geometric 
  operations, such as convolution, scaling, or rotation. 
  <P><A name=74280>
  <HR>

  <CENTER><IMG 
  src="Image Enhancement.files/Image-enhance.doc.anc17.gif"></CENTER>
  <HR>
  </A><A name=74281>
  <CENTER><FONT size=-1><B><I>Figure 7-4 </I><IMG 
  src="Image Enhancement.files/sm-blank.gif" border=0> BorderExtenderCopy 
  Example</B></FONT></CENTER></A>
  <P>
  <TABLE border=0>
    <TBODY>
    <TR>
      <TD><IMG src="Image Enhancement.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>javax.media.jai.BorderExtenderCopy </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>final void extend(WritableRaster raster, PlanarImage im)
<P></P></LI></UL></PRE>
  <DL><A name=73098>
    <DT>
    <DD>fills in the portions of a given <CODE>Raster</CODE> that lie outside 
    the bounds of a given <CODE>PlanarImage</CODE> with copies of the edge 
    pixels of the image. The portion of <CODE>Raster</CODE> that lies within 
    <CODE>im.getBounds</CODE> is not altered. </A>
    <P></P></DD></DL><A name=73128>
  <H4>7.2.2.4 <IMG 
  src="Image Enhancement.files/space.gif">BorderExtenderWrap</H4></A>The 
  <CODE>BorderExtenderWrap</CODE> class is a subclass of 
  <CODE>BorderExtender</CODE> that implements border extension by filling all 
  pixels outside of the image bounds with copies of the whole image. For 
  example, <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Image-enhance.doc.html#74469">Figure 
  7-5</A> shows the result of using <CODE>BorderExtenderWrap</CODE> to extend an 
  image by adding two extra rows to the top and bottom and two extra columns on 
  the left and right sides. 
  <P>This form of extension is appropriate for data that is inherently periodic, 
  such as the Fourier transform of an image or a wallpaper pattern. 
  <P><A name=74468>
  <HR>

  <CENTER><IMG 
  src="Image Enhancement.files/Image-enhance.doc.anc18.gif"></CENTER>
  <HR>
  </A><A name=74469>
  <CENTER><FONT size=-1><B><I>Figure 7-5 </I><IMG 
  src="Image Enhancement.files/sm-blank.gif" border=0> BorderExtenderWrap 
  Example</B></FONT></CENTER></A>
  <P>
  <TABLE border=0>
    <TBODY>
    <TR>
      <TD><IMG src="Image Enhancement.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>javax.media.jai.BorderExtenderWrap </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>final void extend(WritableRaster raster, PlanarImage im)
<P></P></LI></UL></PRE>
  <DL><A name=73485>
    <DT>
    <DD>Fills in the portions of a given <CODE>Raster</CODE> that lie outside 
    the bounds of a given <CODE>PlanarImage</CODE> with copies of the entire 
    image. The portion of <CODE>Raster</CODE> that lies within 
    <CODE>im.getBounds</CODE> is not altered. </A>
    <P></P></DD></DL><A name=73456>
  <H4>7.2.2.5 <IMG 
  src="Image Enhancement.files/space.gif">BorderExtenderReflect</H4></A>The 
  <CODE>BorderExtenderReflect</CODE> class is a subclass of 
  <CODE>BorderExtender</CODE> that implements border extension by filling all 
  pixels outside the image bounds with reflected copies of the whole image. For 
  example, <A 
  href="http://java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Image-enhance.doc.html#74693">Figure 
  7-6</A> shows the result of using <CODE>BorderExtenderReflect</CODE> to extend 
  an image by adding two extra rows to the top and bottom and one extra column 
  on the left and right sides. 
  <P>This form of extension avoids discontinuities around the edges of the 
  image. 
  <P><A name=74688>
  <HR>

  <CENTER><IMG 
src="Image Enhancement.files/Image-enhance.doc.anc3.gif"></CENTER>
  <HR>
  </A><A name=74693>
  <CENTER><FONT size=-1><B><I>Figure 7-6 </I><IMG 
  src="Image Enhancement.files/sm-blank.gif" border=0> BorderExtenderReflect 
  Example</B></FONT></CENTER></A>
  <P>
  <TABLE border=0>
    <TBODY>
    <TR>
      <TD><IMG src="Image Enhancement.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>javax.media.jai.BorderExtenderReflect </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>final void extend(WritableRaster raster, PlanarImage im)
<P></P></LI></UL></PRE>
  <DL><A name=73832>
    <DT>
    <DD>Fills in the portions of a given <CODE>Raster</CODE> that lie outside 
    the bounds of a given <CODE>PlanarImage</CODE> with suitably reflected 
    copies of the entire image. The portion of <CODE>Raster</CODE> that lies 
    within <CODE>im.getBounds</CODE> is not altered. </A>
    <P></P></DD></DL><A name=73080>
  <H2>7.3 <IMG src="Image Enhancement.files/space.gif">Cropping an 
  Image</H2></A>The <CODE>Crop</CODE> operation crops a rendered or renderable 
  image to a specified rectangular area. The <EM>x</EM>, <EM>y</EM>, width, and 
  height values are clipped to the source image's bounding box. These values are 
  rounded to type <CODE>int</CODE> for rendered images. 
  <P>The <CODE>Crop</CODE> operation takes one rendered or renderable source 
  image and four parameters. None of the parameters have default values; all 
  must be supplied.
  <P>
  <TABLE cellPadding=3 border=3>
    <CAPTION><FONT size=-1><B></B></FONT></CAPTION>
    <TBODY>
    <TR vAlign=top>
      <TH><A name=76471>Parameter </A>
      <TH><A name=76473>Type </A>
      <TH><A name=76475>Description </A>
    <TR vAlign=top>
      <TD><A name=76477>x</A><BR>
      <TD><A name=76479>Float</A><BR>
      <TD><A name=76481>The <EM>x</EM> origin for each band.</A><BR>
    <TR vAlign=top>
      <TD><A name=76483>y</A><BR>
      <TD><A name=76485>Float</A><BR>
      <TD><A name=76487>The <EM>y</EM> origin for each band.</A><BR>
    <TR vAlign=top>
      <TD><A name=76489>width</A><BR>
      <TD><A name=76491>Float</A><BR>
      <TD><A name=76493>The width for each band.</A><BR>
    <TR vAlign=top>
      <TD><A name=76495>height</A><BR>
      <TD><A name=76497>Float</A><BR>
      <TD><A name=76499>The height for each band.</A><BR></TR></TBODY></TABLE>
  <P><A name=76505>
  <HR>

  <CENTER><IMG 
src="Image Enhancement.files/Image-enhance.doc.anc8.gif"></CENTER>
  <HR>
  </A><A name=76506>
  <CENTER><FONT size=-1><B><I>Figure 7-7 </I><IMG 
  src="Image Enhancement.files/sm-blank.gif" border=0> Crop 
  Operation</B></FONT></CENTER></A>
  <P><A name=76502>
  <H2>7.4 <IMG src="Image Enhancement.files/space.gif">Amplitude 
  Rescaling</H2></A>Amplitude rescaling provides a linear amplitude 
  transformation of input pixel values to output pixel values. Amplitude 
  rescaling can be used to enhance images that have insufficient contrast 
  between the lightest and darkest values, such as caused by underexposure or 
  overexposure of the original image. 
  <P>The full dynamic range of one band of an eight-bit image is 0 to 255. An 
  underexposed image may only contain pixel values from 10 to 180, resulting in 
  an image that does not fully use the dynamic range of the display. Such an 
  image can be greatly improved by linearly stretching the contrast range; 
  mapping the lowest values to 0 and the highest values to 255. 
  <P>The <CODE>rescale</CODE> operation takes a rendered or renderable source 
  image and maps the pixel values of the image from one range to another range 
  by multiplying each pixel value by one of a set of constants and then adding 
  another constant to the result of the multiplication. If the number of 
  constants supplied is less than the number of bands of the destination, the 
  constant from entry 0 is applied to all the bands. Otherwise, a constant from 
  a different entry is applied to each band. There must be at least one entry in