bmp.html

各种文件格式说明及程序描述

the bitmap data in bytes. this number must be rounded to the next 4 byte boundary.</font></td>
</tr>
<tr>
<td width="10%" valign="top"><font face="book antiqua" size="3"><p align="justify">0026h</font></td>
<td width="16%" valign="top"><font face="book antiqua" size="3"><p align="justify">hresolution</font></td>
<td width="14%" valign="top"><font face="book antiqua" size="3"><p align="justify">1 dword</font></td>
<td width="61%" valign="top"><font face="book antiqua" size="3"><p align="justify">horizontal
resolution expressed in pixel per meter.</font></td>
</tr>
<tr>
<td width="10%" valign="top"><font face="book antiqua" size="3"><p align="justify">002ah</font></td>
<td width="16%" valign="top"><font face="book antiqua" size="3"><p align="justify">vresolution</font></td>
<td width="14%" valign="top"><font face="book antiqua" size="3"><p align="justify">1 dword</font></td>
<td width="61%" valign="top"><font face="book antiqua" size="3"><p align="justify">vertical
resolution expressed in pixels per meter.</font></td>
</tr>
<tr>
<td width="10%" valign="top"><font face="book antiqua" size="3"><p align="justify">002eh</font></td>
<td width="16%" valign="top"><font face="book antiqua" size="3"><p align="justify">colors</font></td>
<td width="14%" valign="top"><font face="book antiqua" size="3"><p align="justify">1 dword</font></td>
<td width="61%" valign="top"><font face="book antiqua" size="3"><p align="justify">number
of colors used by this bitmap. for a 8-bit / pixel bitmap this will be 100h or 256.</font></td>
</tr>
<tr>
<td width="10%" valign="top"><font face="book antiqua" size="3"><p align="justify">0032h</font></td>
<td width="16%" valign="top"><font face="book antiqua" size="3"><p align="justify">important
colors</font></td>
<td width="14%" valign="top"><font face="book antiqua" size="3"><p align="justify">1 dword</font></td>
<td width="61%" valign="top"><font face="book antiqua" size="3"><p align="justify">number
of important colors. this number will be equal to the number of colors when every color is
important.</font></td>
</tr>
<tr>
<td width="10%" valign="top"><font face="book antiqua" size="3"><p align="justify">0036h</font></td>
<td width="16%" valign="top"><font face="book antiqua" size="3"><p align="justify">palette</font></td>
<td width="14%" valign="top"><font face="book antiqua" size="3"><p align="justify">n * 4
byte</font></td>
<td width="61%" valign="top"><font face="book antiqua" size="3"><p align="justify">the
palette specification. for every entry in the palette four bytes are used to describe the
rgb values of the color in the following way:</p>
<p align="justify">1 byte for blue component</p>
<p align="justify">1 byte for green component</p>
<p align="justify">1 byte for red component</p>
<p align="justify">1 byte filler which is set to 0 (zero)</font></td>
</tr>
<tr>
<td width="10%" valign="top"><font face="book antiqua" size="3"><p align="justify">0436h</font></td>
<td width="16%" valign="top"><font face="book antiqua" size="3"><p align="justify">bitmap
data</font></td>
<td width="14%" valign="top"><font face="book antiqua" size="3"><p align="justify">x bytes</font></td>
<td width="61%" valign="top"><font face="book antiqua" size="3"><p align="justify">depending
on the compression specifications, this field contains all the bitmap data bytes which
represent indices in the color palette.</font></td>
</tr>
</table>
<font face="宋体" lang="zh-cn" size="3"><p align="justify">　</p>
</font><font face="book antiqua" size="3"><i><b><p align="justify">note:</b> the following
sizes were used in the specification above: </p>
</i></font><table border="1" cellspacing="2" bordercolor="#000000" cellpadding="7"
width="226">
<tr>
<td width="30%" valign="top"><font face="book antiqua" size="3" color="#808080"><b><p
align="justify">size</b></font></td>
<td width="32%" valign="top"><font face="book antiqua" size="3" color="#808080"><b><p
align="justify"># bytes</b></font></td>
<td width="37%" valign="top"><font face="book antiqua" size="3" color="#808080"><b><p
align="justify">sign</b></font></td>
</tr>
<tr>
<td width="30%" valign="top"><font face="book antiqua" size="3"><p align="justify">char</font></td>
<td width="32%" valign="top"><font face="book antiqua" size="3"><p align="justify">1</font></td>
<td width="37%" valign="top"><font face="book antiqua" size="3"><p align="justify">signed</font></td>
</tr>
<tr>
<td width="30%" valign="top"><font face="book antiqua" size="3"><p align="justify">word</font></td>
<td width="32%" valign="top"><font face="book antiqua" size="3"><p align="justify">2</font></td>
<td width="37%" valign="top"><font face="book antiqua" size="3"><p align="justify">unsigned</font></td>
</tr>
<tr>
<td width="30%" valign="top"><font face="book antiqua" size="3"><p align="justify">dword</font></td>
<td width="32%" valign="top"><font face="book antiqua" size="3"><p align="justify">4</font></td>
<td width="37%" valign="top"><font face="book antiqua" size="3"><p align="justify">unsigned</font></td>
</tr>
</table>
<b><font face="宋体" lang="zh-cn" size="6"><p align="justify"></font><font
face="book antiqua" size="6"><a name="_toc381201085">field details</a></p>
</font></b><font face="book antiqua" size="3"><p align="justify">some of the fields
require some more information. the following chapters will try to provide this
information:</p>
</font><b><font face="宋体" lang="zh-cn" size="5"><p></font><font face="book antiqua"
size="5"><a name="_toc381201086">height field</a></p>
</font></b><font face="book antiqua" size="3"><p align="justify">the <i>height</i> field
identifies the height of the bitmap in pixels. in other words, it describes the number of
scan lines of the bitmap. if this field is negative, indicating a top-down dib, the <i>compression</i>
field must be either bi_rgb or bi_bitfields. top-down dibs cannot be compressed.</p>
</font><b><font face="宋体" lang="zh-cn" size="5"><p></font><font face="book antiqua"
size="5"><a name="_toc381201087">bits per pixel field</a></p>
</font></b><font face="book antiqua" size="3"><p align="justify">the <i>bits per pixel</i>
(bbp) field of the bitmap file determines the number of bits that define each pixel and
the maximum number of colors in the bitmap.</p>
</font><font face="宋体" lang="zh-cn" size="3"><ul>
</font><font face="book antiqua" size="3"><b>
<li>when this field is equal to 1.</li>
</ul>
</b></font><font face="宋体" lang="zh-cn" size="3"><dir>
<dir>
</font><font face="book antiqua" size="3"><p align="justify">the bitmap is monochrome, and
the palette contains two entries. each bit in the bitmap array represents a pixel. if the
bit is clear, the pixel is displayed with the color of the first entry in the palette; if
the bit is set, the pixel has the color of the second entry in the table.</p>
</font><font face="宋体" lang="zh-cn" size="3"><p align="justify">　</p>
</dir>
</dir>
<ul>
</font><font face="book antiqua" size="3"><b>
<li>when this field is equal to 4.</li>
</ul>
</b></font><font face="宋体" lang="zh-cn" size="3"><dir>
<dir>
</font><font face="book antiqua" size="3"><p align="justify">the bitmap has a maximum of
16 colors, and the palette contains up to 16 entries. each pixel in the bitmap is
represented by a 4-bit index into the palette. for example, if the first byte in the
bitmap is 1fh, the byte represents two pixels. the first pixel contains the color in the
second palette entry, and the second pixel contains the color in the sixteenth palette
entry.</p>
</font><font face="宋体" lang="zh-cn" size="3"><p align="justify">　</p>
</dir>
</dir>
<ul>
</font><font face="book antiqua" size="3"><b>
<li>when this field is equal to 8.</li>
</ul>
</b></font><font face="宋体" lang="zh-cn" size="3"><dir>
<dir>
</font><font face="book antiqua" size="3"><p align="justify">the bitmap has a maximum of
256 colors, and the palette contains up to 256 entries. in this case, each byte in the
array represents a single pixel.</p>
<p align="justify"></font><font size="3">　</font><font face="book antiqua" size="3"></p>
</dir>
</dir>
<ul>
<b>
<li>when this field is equal to 16.</li>
</ul>
</b></font><font face="宋体" lang="zh-cn" size="3"><dir>
<dir>
</font><font face="book antiqua" size="3"><p align="justify">the bitmap has a maximum of
2^16 colors. if the <i>compression</i> field of the bitmap file is set to bi_rgb, the <i>palette</i>
field does not contain any entries. each word in the bitmap array represents a single
pixel. the relative intensities of red, green, and blue are represented with 5 bits for
each color component. the value for blue is in the least significant 5 bits, followed by 5
bits each for green and red, respectively. the most significant bit is not used.</p>
<p align="justify">if the <i>compression</i> field of the bitmap file is set to
bi_bitfields, the <i>palette</i> field contains three dword color masks that specify the
red, green, and blue components, respectively, of each pixel. each word in the bitmap
array represents a single pixel.</p>
<b><p align="justify">windows nt specific:</b> when the <i>compression</i> field is set to
bi_bitfields, bits set in each dword mask must be contiguous and should not overlap the
bits of another mask. all the bits in the pixel do not have to be used. </p>
<b><p align="justify">windows 95 specific:</b> when the <i>compression</i> field is set to
bi_bitfields, windows 95 supports only the following 16bpp color masks: a 5-5-5 16-bit
image, where the blue mask is 0x001f, the green mask is 0x03e0, and the red mask is
0x7c00; and a 5-6-5 16-bit image, where the blue mask is 0x001f, the green mask is 0x07e0,
and the red mask is 0xf800.</p>
<p align="justify"></font><font size="3">　</font><font face="book antiqua" size="3"></p>
</dir>
</dir>
<ul>
<b>
<li>when this field is equal to 24.</li>
</ul>
</b></font><font face="宋体" lang="zh-cn" size="3"><dir>
<dir>
</font><font face="book antiqua" size="3"><p align="justify">the bitmap has a maximum of
2^24 colors, and the <i>palette</i> field does not contain any entries. each 3-byte
triplet in the bitmap array represents the relative intensities of blue, green, and red,
respectively, for a pixel.</p>
</font><font face="宋体" lang="zh-cn" size="3"><p align="justify">　</p>
</dir>
</dir>
<ul>
</font><font face="book antiqua" size="3"><b>
<li>when this field is equal to 32.</li>
</ul>
</b></font><font face="宋体" lang="zh-cn" size="3"><dir>
<dir>
</font><font face="book antiqua" size="3"><p align="justify">the bitmap has a maximum of
2^32 colors. if the <i>compression</i> field of the bitmap is set to bi_rgb, the <i>palette</i>
field does not contain any entries. each dword in the bitmap array represents the relative
intensities of blue, green, and red, respectively, for a pixel. the high byte in each
dword is not used.</p>
<p align="justify">if the <i>compression</i> field of the bitmap is set to bi_bitfields,
the palette field contains three dword color masks that specify the red, green, and blue
components, respectively, of each pixel. each dword in the bitmap array represents a
single pixel.</p>
<b><p align="justify">windows nt specific:</b> when the <i>compression</i> field is set to