writing image files.htm

是一部关于java高级图像处理的的一本入门书

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      <TD><IMG src="Writing Image Files.files/cistine.gif"></TD>
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        <B>API:</B> <CODE>com.sun.media.jai.codec.PNGEncodeParam </CODE>
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      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>int filterRow(byte[] currRow, byte[] prevRow, 
       byte[][]  scratchRows, int bytesPerRow, int bytesPerPixel)
<P></P></LI></UL></PRE>
  <DL><A name=54138>
    <DT>
    <DD>returns the type of filtering to be used on a row of an image.
    <P>
    <TABLE cellPadding=3 border=3>
      <CAPTION><FONT size=-1><B></B></FONT></CAPTION>
      <TBODY>
      <TR vAlign=top>
        <TD rowSpan=5><EM>Parameters</EM>:<EM></EM> 
          <P></P>
        <TD><CODE>currRow</CODE> 
          <P></P>
        <TD>The current row as an array of <CODE>byte</CODE>s of length at 
          least <CODE>bytesPerRow</CODE> + <CODE>bytesPerPixel</CODE>. The pixel 
          data starts at index <CODE>bytesPerPixel</CODE>; the initial 
          <CODE>bytesPerPixel</CODE> bytes are zero. 
          <P></P>
      <TR vAlign=top>
        <TD><CODE>prevRow</CODE> 
          <P></P>
        <TD>The current row as an array of <CODE>byte</CODE>s. The pixel data 
          starts at index <CODE>bytesPerPixel</CODE>; the initial 
          <CODE>bytesPerPixel</CODE> bytes are zero. 
          <P></P>
      <TR vAlign=top>
        <TD><CODE>scratchRows</CODE> 
          <P></P>
        <TD>An array of 5 <CODE>byte</CODE> arrays of length at least 
          <CODE>bytesPerRow</CODE> + <CODE>bytesPerPixel</CODE>, usable to hold 
          temporary results. The filtered row will be returned as one of the 
          entries of this array. The returned filtered data should start at 
          index <CODE>bytesPerPixel</CODE>; The initial 
          <CODE>bytesPerPixel</CODE> bytes are not used. 
          <P></P>
      <TR vAlign=top>
        <TD><CODE>bytesPerRow</CODE> 
          <P></P>
        <TD>The number of bytes in the image row. This value will always be 
          greater than 0. 
          <P></P>
      <TR vAlign=top>
        <TD><CODE>bytesPerPixel</CODE> 
          <P></P>
        <TD>The number of bytes representing a single pixel, rounded up to an 
          integer. This is the <CODE>bpp</CODE> parameter described in the PNG 
          specification. 
          <P></P></TR></TBODY></TABLE></A>
    <P></P></DD></DL><A name=53673>
  <H3>13.6.3 <IMG src="Writing Image Files.files/space.gif">Bit 
  Depth</H3></A>The PNG specification identifies the following bit depth 
  restrictions for each of the color types:
  <P>
  <TABLE cellPadding=3 border=3>
    <CAPTION><FONT size=-1><B><A name=53677><I>Table 13-4 </I><IMG 
    src="Writing Image Files.files/sm-blank.gif" border=0> PNG Bit Depth 
    Restrictions </A></B></FONT></CAPTION>
    <TBODY>
    <TR vAlign=top>
      <TH><A name=53683>Color Type </A>
      <TH><A name=53685>Allowed Bit Depths </A>
      <TH><A name=53687>Description </A>
    <TR vAlign=top>
      <TD><A name=53689>0</A><BR>
      <TD><A name=53691>1, 2, 4, 8, 16</A><BR>
      <TD><A name=53693>Grayscale. Each pixel is a grayscale sample.</A><BR>
    <TR vAlign=top>
      <TD><A name=53695>2</A><BR>
      <TD><A name=53697>8, 16</A><BR>
      <TD><A name=53699>Truecolor (RGB) without alpha. Each pixel is an RGB 
        triple.</A><BR>
    <TR vAlign=top>
      <TD><A name=53701>3</A><BR>
      <TD><A name=53703>1, 2, 4, 8</A><BR>
      <TD><A name=53705>Indexed color (Palette). Each pixel is a palette 
        index.</A><BR>
    <TR vAlign=top>
      <TD><A name=53707>4</A><BR>
      <TD><A name=53709>8, 16</A><BR>
      <TD><A name=53711>Grayscale with alpha. Each pixel is a grayscale sample 
        followed by an alpha sample.</A><BR>
    <TR vAlign=top>
      <TD><A name=53713>6</A><BR>
      <TD><A name=53715>8, 16</A><BR>
      <TD><A name=53717>Truecolor (RGB) with alpha. Each pixel is an RGB 
        triple followed by an alpha sample.</A><BR></TR></TBODY></TABLE>
  <P>The bit depth is specified by the <CODE>setBithDepth</CODE> method in the 
  class type. 
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      <TD><IMG src="Writing Image Files.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>com.sun.media.jai.codec.PNGEncodeParam.Palette </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>void setBitDepth(int bitDepth)
<P></P></LI></UL></PRE>
  <DL><A name=53723>
    <DT>
    <DD>sets the desired bit depth for a palette image. The bit depth must be 1, 
    2, 4, or 8. </A>
    <P></P></DD></DL>
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      <TD><IMG src="Writing Image Files.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>com.sun.media.jai.codec.PNGEncodeParam.Gray </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>public void setBitDepth(int bitDepth)
<P></P></LI></UL></PRE>
  <DL><A name=57396>
    <DT>
    <DD>sets the desired bit depth for a grayscale image. The bit depth must be 
    1, 2, 4, 8, or 16. </A>
    <P></P></DD></DL>
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      <TD><IMG src="Writing Image Files.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>com.sun.media.jai.codec.PNGEncodeParam.RGB </CODE>
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      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>void setBitDepth(int bitDepth)
<P></P></LI></UL></PRE>
  <DL><A name=53729>
    <DT>
    <DD>sets the desired bit depth for an RGB image. The bit depth must be 8 or 
    16. </A>
    <P></P></DD></DL><A name=53730>
  <H3>13.6.4 <IMG src="Writing Image Files.files/space.gif">Interlaced Data 
  Order</H3></A>The interlaced data order indicates the transmission order of 
  the image data. Two settings are currently allowed: no interlace and Adam7 
  interlace. With interlacing turned off, pixels are stored sequentially from 
  left to right, and scanlines sequentially from top to bottom. Adam7 
  interlacing (named after its author, Adam M. Costello), consists of seven 
  distinct passes over the image; each pass transmits a subset of the pixels in 
  the image. 
  <P>
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      <TD><IMG src="Writing Image Files.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>com.sun.media.jai.codec.PNGEncodeParam </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>void setInterlacing(boolean useInterlacing)
<P></P></LI></UL></PRE>
  <DL><A name=53736>
    <DT>
    <DD>turns Adam7 interlacing on or off. </A>
    <P></P></DD></DL><PRE><UL>
<LI>boolean getInterlacing()
<P></P></LI></UL></PRE>
  <DL><A name=53738>
    <DT>
    <DD>returns <CODE>true</CODE> if Adam7 interlacing will be used. </A>
    <P></P></DD></DL><A name=53779>
  <H3>13.6.5 <IMG src="Writing Image Files.files/space.gif">PLTE Chunk for 
  Palette Images</H3></A>The PLTE chunk provides the palette information palette 
  or indexed-color images. The PLTE chunk must be supplied for all palette 
  (color type 3) images and is optional for RGB (color type 2 and 6) images. 
  <P>The PLTE chunk contains from 1 to 256 palette entries, each a three-byte 
  series of the alternating red, green, and blue values, as follows: 
  <P>
  <UL>
    <LI>Red: one byte (0 = black, 255 = red)
    <P></P></LI></UL>
  <UL>
    <LI>Green: one byte (0 = black, 255 = green)
    <P></P></LI></UL>
  <UL>
    <LI>Blue: one byte (0 = black, 255 = blue)
    <P></P></LI></UL>The number of elements in the palette must be a multiple of 
  3, between 3 and 768 (3 x 256). The first entry in the palette is referenced 
  by pixel value 0, the second by pixel value 1, and so on. 
  <P>For RGB (color type 2 and 6) images, the PLTE chunk, if included, provides 
  a suggested set of from 1 to 256 colors to which the RGB image can be 
  quantized in case the viewing system cannot display RGB directly. 
  <P>
  <TABLE border=0>
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      <TD><IMG src="Writing Image Files.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>com.sun.media.jai.codec.PNGEncodeParam </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>void setPalette(int[] rgb)
<P></P></LI></UL></PRE>
  <DL><A name=53819>
    <DT>
    <DD>sets the RGB palette of the image to be encoded.
    <P>
    <TABLE cellPadding=3 border=3>
      <CAPTION><FONT size=-1><B></B></FONT></CAPTION>
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      <TR vAlign=top>
        <TD><EM>Parameters</EM>:<EM></EM> 
          <P></P>
        <TD><CODE>rgb</CODE> 
          <P></P>
        <TD>An array of <CODE>int</CODE>s. 
          <P></P></TR></TBODY></TABLE></A>
    <P></P></DD></DL><PRE><UL>
<LI>int[] getPalette()
<P></P></LI></UL></PRE>
  <DL><A name=53855>
    <DT>
    <DD>returns the current RGB palette. </A>
    <P></P></DD></DL><PRE><UL>
<LI>void unsetPalette()
<P></P></LI></UL></PRE>
  <DL><A name=53865>
    <DT>
    <DD>suppresses the PLTE chunk from being output. </A>
    <P></P></DD></DL><PRE><UL>
<LI>boolean isPaletteSet()
<P></P></LI></UL></PRE>
  <DL><A name=53875>
    <DT>
    <DD>returns true if a PLTE chunk will be output. </A>
    <P></P></DD></DL><A name=53197>
  <H3>13.6.6 <IMG src="Writing Image Files.files/space.gif">Ancillary Chunk 
  Specifications</H3></A>All ancillary PNG chunks are optional but are 
  recommended. Most of the PNG chunks can be specified prior to encoding the 
  image by <CODE>set</CODE> methods in the <CODE>PNGEncodeParam</CODE> class. 
  The chunks that can be set and the methods used to set them are described in 
  the following paragraphs. 
  <P><A name=51917>
  <H4>13.6.6.1 <IMG src="Writing Image Files.files/space.gif">Background Color 
  (bKGD Chunk)</H4></A>Methods are provided to set and read the suggested 
  background color, which is encoded by the bKGD chunk. 
  <P>For Palette (indexed color) images, the bKGD chunk contains a single value, 
  which is the palette index of the color to be used as the background. 
  <P>For Grayscale images, the bKGD chunk contains a single value, which is the 
  gray level to be used as the background. The range of values is 0 to 
  2<SUP>bitdepth</SUP> - 1. 
  <P>For RGB (truecolor) images, the bKGD chunk contains three values, one each 
  for red, green, and blue. Each value has the range of 0 to 
  2<SUP>bitdepth</SUP> - 1. 
  <P>
  <TABLE border=0>
    <TBODY>
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      <TD><IMG src="Writing Image Files.files/cistine.gif"></TD>
      <TD>
        <HR>
        <B>API:</B> <CODE>com.sun.media.jai.codec.PNGEncodeParam.Palette </CODE>
        <HR>
      </TD></TR></TBODY></TABLE><PRE><UL>
<LI>void setBackgroundPaletteIndex(int index)
<P></P></LI></UL></PRE>
  <DL><A name=51955>
    <DT>
    <DD>sets the palette index of the suggested background color. </A>
    <P></P></DD></