Graphics File Formats(Windows的.BMP .CUR .ICO文件的格式，有范例)

02 78 78 78
00 00 end of line
09 1e 1e 1e 1e 1e 1e 1e 1e 1e 1e
00 01 end of rle bitmap

compression of 4-bits-per-pixel bitmaps

when the bicompression member of the bitmapinfoheader structure is set to
bi_rle4, the dib is compressed using a run-length encoded format for a
16-color bitmap. this format uses two modes: encoded mode and absolute mode.

encoded mode

a unit of information in encoded mode consists of two bytes. the first byte
of the pair contains the number of pixels to be drawn using the color indexes
in the second byte.

the second byte contains two color indexes, one in its high-order nibble
(that is, its low-order 4 bits) and one in its low-order nibble.

the first pixel is drawn using the color specified by the high-order nibble,
the second is drawn using the color in the low-order nibble, the third is
drawn with the color in the high-order nibble, and so on, until all the
pixels specified by the first byte have been drawn.

the first byte of the pair can be set to zero to indicate an escape that
denotes the end of a line, the end of the bitmap, or a delta. the
interpretation of the escape depends on the value of the second byte of the
pair. in encoded mode, the second byte has a value in the range 0x00 through
0x02. the meaning of these values is the same as for a dib with 8 bits per
pixel.

absolute mode

in absolute mode, the first byte contains zero, the second byte contains the
number of color indexes that follow, and subsequent bytes contain color
indexes in their high- and low-order nibbles, one color index for each pixel.
each run must be aligned on a word boundary.

following is an example of a 4-bit rle bitmap (the one-digit hexadecimal
values in the second column represent a color index for a single pixel):

compressed data expanded data

03 04 0 4 0
05 06 0 6 0 6 0
00 06 45 56 67 00 4 5 5 6 6 7
04 78 7 8 7 8
00 02 05 01 move 5 right and 1 down
04 78 7 8 7 8
00 00 end of line
09 1e 1 e 1 e 1 e 1 e 1
00 01 end of rle bitmap

bitmap example

the following example is a text dump of a 16-color bitmap (4 bits per pixel):

win3dibfile
bitmapfileheader
type 19778
size 3118
reserved1 0
reserved2 0
offsetbits 118
bitmapinfoheader
size 40
width 80
height 75
planes 1
bitcount 4
compression 0
sizeimage 3000

xpelspermeter 0
ypelspermeter 0
colorsused 16
colorsimportant 16
win3colortable
blue green red unused
[00000000] 84 252 84 0
[00000001] 252 252 84 0
[00000002] 84 84 252 0
[00000003] 252 84 252 0
[00000004] 84 252 252 0
[00000005] 252 252 252 0
[00000006] 0 0 0 0
[00000007] 168 0 0 0
[00000008] 0 168 0 0
[00000009] 168 168 0 0
[0000000a] 0 0 168 0
[0000000b] 168 0 168 0
[0000000c] 0 168 168 0
[0000000d] 168 168 168 0
[0000000e] 84 84 84 0
[0000000f] 252 84 84 0
image
.
. bitmap data
.

icon-resource file format

an icon-resource file contains image data for icons used by windows
applications. the file consists of an icon directory identifying the number
and types of icon images in the file, plus one or more icon images. the
default filename extension for an icon-resource file is .ico.

icon directory

each icon-resource file starts with an icon directory. the icon directory,

本新闻共13页,当前在第03页
01  02  03  04  05  06  07  08  09  10
11  12  13

上一篇：bmp format(bmp文件格式)

下一篇：AI文件格式(ai file format)

/0�9r