daubnet file formats collection bmp.htm

通过bmp图片格式进行数据加密

                  high order 4 bits representing the left of those. There are 16 
                  color table entries. These colors do not have to be the 16 
                  MS-Windows standard colors. Padding each line with zeros up to 
                  a 32bit boundary will result in up to 28 zeros = 7 'wasted 
                  pixels'.</FONT></TD></TR></TBODY></TABLE></CENTER>&nbsp; 
            <CENTER>
            <TABLE width="90%">
              <TBODY>
              <TR>
                <TD>
                  <H3><A href="http://www.daubnet.com/formats/BMP.html#Top"><IMG 
                  height=20 alt="to top" 
                  src="DaubNET File Formats Collection BMP.files/totop.gif" 
                  width=20 align=right border=0 NOSAVE></A><A 
                  name=Raster8></A><FONT face=Arial,Helvetica>Raster Data 
                  encoding for 8bit / 256 color images</FONT></H3><FONT 
                  face=Arial,Helvetica>BitCount = 8 Compression = 0</FONT>&nbsp; 
                  <BR><FONT face=Arial,Helvetica>Every byte holds 1 pixel. There 
                  are 256 color table entries. Padding each line with zeros up 
                  to a 32bit boundary will result in up to 3 bytes of zeros = 3 
                  'wasted pixels'.</FONT></TD></TR></TBODY></TABLE></CENTER>&nbsp; 
            <CENTER>
            <TABLE width="90%">
              <TBODY>
              <TR>
                <TD>
                  <H3><A href="http://www.daubnet.com/formats/BMP.html#Top"><IMG 
                  height=20 alt="to top" 
                  src="DaubNET File Formats Collection BMP.files/totop.gif" 
                  width=20 align=right border=0 NOSAVE></A><A 
                  name=Raster24></A><FONT face=Arial,Helvetica>Raster Data 
                  encoding for 16bit / hicolor images</FONT></H3><FONT 
                  face=Arial,Helvetica>BitCount = 16 Compression = 
                  0</FONT>&nbsp; <BR><FONT face=Arial,Helvetica>Every 2bytes / 
                  16bit holds 1 pixel.&nbsp;</FONT>&nbsp; <BR><FONT 
                  face=Arial,Helvetica>&lt;<I>information missing</I>: the 16 
                  bit was introduced together with Video For Windows? Is it a 
                  memory-only-format?&gt;</FONT>&nbsp; <BR><FONT 
                  face=Arial,Helvetica>The pixels are no color table pointers. 
                  There are no color table entries. Padding each line with zeros 
                  up to a 16bit boundary will result in up to 2 zero 
                  bytes.</FONT></TD></TR></TBODY></TABLE></CENTER>&nbsp; 
            <CENTER>
            <TABLE width="90%">
              <TBODY>
              <TR>
                <TD>
                  <H3><A href="http://www.daubnet.com/formats/BMP.html#Top"><IMG 
                  height=20 alt="to top" 
                  src="DaubNET File Formats Collection BMP.files/totop.gif" 
                  width=20 align=right border=0 NOSAVE></A><A 
                  name=Raster24></A><FONT face=Arial,Helvetica>Raster Data 
                  encoding for 24bit / truecolor images</FONT></H3><FONT 
                  face=Arial,Helvetica>BitCount = 24 Compression = 
                  0</FONT>&nbsp; <BR><FONT face=Arial,Helvetica>Every 4bytes / 
                  32bit holds 1 pixel. The first holds its red, the second its 
                  green, and the third its blue intensity. The fourth byte is 
                  reserved and should be zero. There are no color table entries. 
                  The pixels are no color table pointers. No zero padding 
                  necessary.</FONT></TD></TR></TBODY></TABLE></CENTER>&nbsp; 
            <CENTER>
            <TABLE width="90%">
              <TBODY>
              <TR>
                <TD>
                  <H3><A href="http://www.daubnet.com/formats/BMP.html#Top"><IMG 
                  height=20 alt="to top" 
                  src="DaubNET File Formats Collection BMP.files/totop.gif" 
                  width=20 align=right border=0 NOSAVE></A><A 
                  name=Raster4RLE></A><FONT face=Arial,Helvetica>Raster Data 
                  compression for 4bit / 16 color images</FONT></H3><FONT 
                  face=Arial,Helvetica>BitCount = 4 Compression = 2</FONT>&nbsp; 
                  <BR><FONT face=Arial,Helvetica>The pixel data is stored in 
                  2bytes / 16bit chunks.&nbsp; The first of these specifies the 
                  number of consecutive pixels with the same pair of color. The 
                  second byte defines two color indices. The resulting pixel 
                  pattern will be interleaved high-order 4bits and low order 4 
                  bits (ABABA...). If the first byte is zero, the second defines 
                  an escape code. The End-of-Bitmap is zero padded to end on a 
                  32bit boundary. Due to the 16bit-ness of this structure this 
                  will always be either two zero bytes or 
                  none.&nbsp;</FONT>&nbsp; <BR>&nbsp; 
                  <TABLE>
                    <TBODY>
                    <TR>
                      <TD><FONT face=Arial,Helvetica><B>n</B> (byte 
                      1)</FONT></TD>
                      <TD><FONT face=Arial,Helvetica><B>c</B> (Byte 
                      2)</FONT></TD>
                      <TH><FONT face=Arial,Helvetica>Description</FONT></TH></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>&gt;0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>any</FONT></TD>
                      <TD><FONT face=Arial,Helvetica><B>n</B> pixels are to be 
                        drawn. The 1st, 3rd, 5th, ... pixels' color is in 
                        <B>c</B>'s high-order 4 bits, the even pixels' color is 
                        in <B>c</B>'s low-order 4 bits. If both color indices 
                        are the same, it results in just <B>n</B> pixels of 
                        color <B>c</B></FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>End-of-line</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>1</FONT></TD>
                      <TD><FONT 
face=Arial,Helvetica>End-of-Bitmap</FONT></TD></TR>
                    <TR vAlign=top>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>2</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>Delta. The following 2 
                        bytes define an unsigned offset in x and y direction (y 
                        being up) The skipped pixels should get a color 
                        zero.</FONT></TD></TR>
                    <TR vAlign=top>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>&gt;=3</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>The following <B>c</B> 
                        bytes will be read as single pixel colors just as in 
                        uncompressed files. up to 12 bits of zeros follow, to 
                        put the file/memory pointer on a 16bit boundary 
                        again.</FONT></TD></TR></TBODY></TABLE>&nbsp; 
                  <TABLE>
                    <CAPTION><B><FONT face=Arial,Helvetica>Example for 4bit 
                    RLE</FONT></B></CAPTION>
                    <TBODY>
                    <TR>
                      <TH><FONT face=Arial,Helvetica>Compressed Data</FONT></TH>
                      <TH><FONT face=Arial,Helvetica>Expanded 
data</FONT></TH></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>03 04</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>0 4 0</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>05 06</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>0 6 0 6 0</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>00 06 45 56 67 
                      00</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>4 5 5 6 6 7</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>04 78</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>7 8 7 8</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>00 02 05 01</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>Move 5 right and 1 up. 
                        (Windows docs say <I>down</I>, which is 
                    wrong)</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>00 00</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>End-of-line</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>09 1E</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>1 E 1 E 1 E 1 E 
                      1</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>00 01</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>EndofBitmap</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>00 00</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>Zero padding for 32bit 
                        boundary</FONT></TD></TR></TBODY></TABLE>&nbsp;</TD></TR></TBODY></TABLE></CENTER>&nbsp; 

            <CENTER>
            <TABLE width="90%">
              <TBODY>
              <TR>
                <TD>
                  <H3><A href="http://www.daubnet.com/formats/BMP.html#Top"><IMG 
                  height=20 alt="to top" 
                  src="DaubNET File Formats Collection BMP.files/totop.gif" 
                  width=20 align=right border=0 NOSAVE></A><A 
                  name=Raster8RLE></A><FONT face=Arial,Helvetica>Raster Data 
                  compression for 8bit / 256 color images</FONT></H3><FONT 
                  face=Arial,Helvetica>BitCount = 8 Compression = 1</FONT>&nbsp; 
                  <BR><FONT face=Arial,Helvetica>The pixel data is stored in 
                  2bytes / 16bit chunks.&nbsp; The first of these specifies the 
                  number of consecutive pixels with the same color. The second 
                  byte defines their color index. If the first byte is zero, the 
                  second defines an escape code. The End-of-Bitmap is zero 
                  padded to end on a 32bit boundary. Due to the 16bit-ness of 
                  this structure this will always be either two zero bytes or 
                  none.&nbsp;</FONT>&nbsp; <BR>&nbsp; 
                  <TABLE>
                    <TBODY>
                    <TR>
                      <TD><FONT face=Arial,Helvetica><B>n</B> (byte 
                      1)</FONT></TD>
                      <TD><FONT face=Arial,Helvetica><B>c</B> (Byte 
                      2)</FONT></TD>
                      <TH><FONT face=Arial,Helvetica>Description</FONT></TH></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>&gt;0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>any</FONT></TD>
                      <TD><FONT face=Arial,Helvetica><B>n</B> pixels of color 
                        number <B>c</B></FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>End-of-line</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>1</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>EndOfBitmap</FONT></TD></TR>
                    <TR vAlign=top>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>2</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>Delta. The following 2 
                        bytes define an unsigned offset in x and y direction (y 
                        being up) The skipped pixels should get a color 
                        zero.</FONT></TD></TR>
                    <TR vAlign=top>
                      <TD><FONT face=Arial,Helvetica>0</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>&gt;=3</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>The following <B>c</B> 
                        bytes will be read as single pixel colors just as in 
                        uncompressed files. A zero follows, if <B>c</B> is odd, 
                        putting the file/memory pointer on a 16bit boundary 
                        again.</FONT></TD></TR></TBODY></TABLE>&nbsp; 
                  <TABLE>
                    <CAPTION><B><FONT face=Arial,Helvetica>Example for 8bit 
                    RLE</FONT></B></CAPTION>
                    <TBODY>
                    <TR>
                      <TH><FONT face=Arial,Helvetica>Compressed Data</FONT></TH>
                      <TH><FONT face=Arial,Helvetica>Expanded 
data</FONT></TH></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>03 04</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>04 04 04</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>05 06</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>06 06 06 06 
                    06</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>00 03 45 56 67 
                      00</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>45 56 67</FONT></TD></TR>
                    <TR>
                      <TD><FONT face=Arial,Helvetica>02 78</FONT></TD>
                      <TD><FONT face=Arial,Helvetica>78 78</FONT></TD></TR>