Description:
The emread module loads an EM file (Hegerl, R. (1996). The EM Program Package: A Platform for Image Processing in
Biological Electron Microscopy, J. Struct. Biol. 116: 30-34), with the
default extension .em. The file can be in little endian or big endian byte ordering with a 512 byte header. The structure of an em
file is as follows:
| - Byte1: Machine coding |
Machine |
Value |
| |
OS-9 |
0 |
| |
VAX |
1 |
| |
CONVEX |
2 |
| |
SGI |
3 |
| |
SUN |
4 (not supported) |
| |
MAC |
5 |
| |
PC |
6 |
| - Byte 2: General purpose |
On OS-9 |
old version 0, new version 1 |
| - Byte 3: Not used in EM-format |
if 1, the header is abandonned |
| - Byte 4: Data type coding |
Image type |
No. of byte |
Value |
|
| |
byte |
1 |
1 |
|
| |
short |
2 |
2 |
|
| |
long int |
4 |
4 |
|
| |
float |
4 |
5 |
|
| |
complex |
8 |
8 |
|
| |
double |
8 |
9 |
|
|
- Three long integers (3x4 bytes) are image size in x, y, z dimension |
|
- 80 characters as comment |
|
- 40 long integers (4x40 bytes) are user defined parameters |
|
- 256 bytes with userdata, first 20 chars username, 8 chars date (i.e.
03/02/03) |
|
- raw data following with the x variable as the fastest dimensions, then y and z |
The structure for the parameters is not described here, because they are not used for the loading of an em file.
How to use:
A file with the default extension .em can be loaded by just double clicking on the file in the open file dialog box. Files
with another extension, which are in an em format, can be loaded by right clicking on the file in the dialog box and choosing
Format from the popup menu. In the file format chooser select "EM Format" and press OK. Press the Open Button in the open file dialog
box.
|
