Also Known As:
Standard Archive Format, AMSC Archive Format, POD
| Type | Bitmap and other (see text) |
| Colors | unlimited |
| Compression | GZIP (see article) |
| Maximum Image Size | Unlimited |
| Multiple Images Per File | No |
| Numerical Format | Any |
| Originator | Advanced Missile Signature Center |
| Platform | All |
| Supporting Applications | Unknown |
| See Also | None |
Usage
Archival storage of multiple data types in one standard
format.
Comments
A flexible format designed for the storage of bitmap and
other types of data.
Vendor specifications are available for this format.
The Advanced Missile Signature Center (AMSC) has created a file format known as the Standard Archive Format (SAF) designed for flexible and extensible use in data archiving. The data may be in ASCII or one of a number of binary formats. The file header is ASCII, however, and can be browsed visually to quickly determine content. As an example of file format technology, it incorporates some unique and interesting features, perhaps reflecting its recent vintage and the experience of its creators.
Contents:
File Organization
File Details
For More Information
A file suffix of .SAF usually indicates that the file contains image data. The .POD suffix is usually reserved for files containing POD (Parameter Oriented Data) information. This article discusses the forms of the file that are appropriate for storing image data. Please refer to the document on the CD-ROM for the complete specification and further information.
The file consists of an ASCII header followed by binary or ASCII data.
This section describes the details of the SAF file header, tags, and image data.
The header, always at the start of the file, begins with the ASCII string "HdSize", followed by the length of the header in bytes. HdSize functions as a designated magic number intended to enhance automated file type recognition. HdSize may be followed by the string "auto", in which case the header must be terminated by the string "data".
The rest of the header consists of a list of tags, or field identifiers, followed by data fields. The number of tags is not fixed, and tags can be in any order. Tags in SAF files are simply names in ASCII text followed by a space and are case-insensitive. Only tags necessary to interpret or render the data are included, which keeps down fixed file overhead. This technique--using variable numbers of tags in the header--was apparently designed to enhance automated file handling and data extraction while maintaining maximum flexibility. The header supports editing revisions after initial file creation and can be extended at will.
The specification allows both standard tags and user-defined tags. Standard tags are 6 characters or less, and user-defined tags may be up to 29 characters in length. ASCII lines may be terminated by either linefeed or carriage return/linefeed pairs.
The following tables, adapted from the SAF specification, list standard tags in SAF files.
Tag | Description | Data Type |
|---|---|---|
HdSize |
Header Size (in bytes, or it may be AUTO) |
Integer |
AqMode |
Acquisition Mode |
Text |
AspAng |
Aspect Angle (degrees) |
Float |
BgFile |
Background File |
Text |
BgType |
Background Type |
Text |
BgValu |
Background Value (Average or Fixed) |
Float |
BPFile |
Bad Pixel File |
Text |
BytOrd |
Byte Order |
Text |
CaFile |
Calibration File |
Text |
ChTemp |
High Temp of Cal Source (degrees C) |
Float |
Class |
Classification |
Text |
CIDay |
Collection IRIG Day |
Integer |
CIHour |
Collection IRIG Hour |
Integer |
CIMin |
Collection IRIG Minute |
Integer |
CISec |
Collection IRIG Seconds |
Float |
ClTemp |
Low Temp of Cal Source (degrees C) |
Float |
COMENT |
Comment Line (Repeated as Required) |
Text |
CSFile |
Calibration Source File |
Text |
Data |
End of header |
|
DaType |
Data Type |
Text |
DaUnit |
Data Units |
Text |
DDOff |
Data Distribution Office |
Text |
DiaFOV |
Circular FOV (degrees) |
Float |
DiStat |
Distribution Statement |
Text |
ElAng |
Elevation Angle (deg) |
Float |
EURAW |
Processed Level of the Data EU/RAW/Flat-fielded (FF) |
Text |
ExpID |
AMSC Experiment ID# |
Text |
Filter |
Filter Name |
Text |
Filtno |
Filter Number |
Integer |
FOVAxl |
Chamber Test FOV Axial Location (meters) |
Float |
FOVRdl |
Chamber Test FOV Radial Location (meters) |
Float |
HdVers |
Header Version (= 2.0) |
Text |
HorFOV |
Horizontal FOV (degrees) |
Float |
IHFOV |
Instantaneous Horizontal FOV (microradians) |
Float |
Itime |
Integration Time (seconds) |
Float |
IVFOV |
Instantaneous Vertical FOV (microradians) |
Float |
LinLog |
Linear/Log Indicator (LIN/LOG/ASG) |
Text |
LODAng |
Observer Line-of-Sight Angle with respect to True North (CW is +) |
Float |
LogASl |
Log Amp Slope |
Float |
LogOff |
Log Offset |
Float |
Mach |
Mach Number |
Float |
Mdate |
Mission Date (MM/DD/YY) |
Text |
MeasUn |
Measurement Uncertainty-Nominal (%) |
Float |
Miss |
Mission |
Text |
NCoads |
Number of Coads |
Integer |
NEQ |
Noise Equivalent Quantity |
Float |
NodeNo |
Node Number |
Text |
Note01 |
Numbered Notes, valid from Note01 through Note99 |
Text |
OffCor |
Offset Correction |
Float |
PPCNam |
Platform AMSC Component Name |
Text |
RDFile |
Raw Data File |
Text |
RolAng |
Roll Angle (degrees) |
Float |
SBPLo |
System Bandpass, Lower Wavelength (microns) |
Float |
SBPUp |
System Bandpass, Upper Wavelength (microns) |
Float |
SclFac |
Calibration or Scale Factor |
Float |
SDLevl |
SDIO Data Level |
Text |
SecCol |
Number of Seconds Collected |
Integer |
SLFile |
Spectral Lamp File |
Text |
SltRng |
Slant Range (meters) |
Float |
SnsAlt |
Sensor Altitude (meters) |
Float |
SPCNam |
Sensor AMSC Component Name |
Text |
Stage |
Launch Vehicle Stage Number |
Float |
StdUnt |
Standard Data Units Index |
Integer |
SUncLo |
Independent Parameter Uncertainty Lower Limit |
Float |
SUncUp |
Independent Parameter Uncertainty Upper Limit |
Float |
TALO |
TALO (seconds) |
Float |
TAOA |
Target Angle of Attack (degrees) |
Float |
Target |
Target Name |
Text |
TestNo |
Test Number |
Text |
TPCNam |
Target PC Component Name |
Text |
TPFact |
Transmission Path Factor |
Float |
TrgAlt |
Target Altitude (meters) |
Float |
TrgHdg |
Target Heading with respect to True North (CW is +) |
Float |
TrgTyp |
Target Type (Liquid/Solid) |
Text |
TrgVel |
Target Velocity (meters/second) |
Float |
TrlNum |
Trial Number |
Text |
TZDay |
T-Zero Day |
Integer |
TZHour |
T-Zero Hour |
Integer |
TZMin |
T-Zero Minute |
Integer |
TZSec |
T-Zero Seconds |
Float |
USRCON |
User-Specified Parameters Header Filename |
Text |
VrtFOV |
Vertical FOV (degrees) |
Float |
Warn01 |
Warning to the user, valid from 01 thru 99 |
Text |
XUncUn |
Independent Parameter Uncertainty Units |
Float |
YUncLo |
Dependent Parameter Uncertainty Lower Limit |
Float |
YUncLo |
Dependent Parameter Uncertainty Upper Limit |
Float |
YUncUn |
Dependent Parameter Uncertainty Units |
Float |
Tag | Description | Data Type |
|---|---|---|
ACFile |
Area Correction Factor File |
Text |
ADJFAC |
Non-Linear Adjustment Factor |
Float |
ApSize |
Aperture Size |
Float |
BGBLLX |
Lower Left X for Background Box |
Integer |
BGBLLY |
Lower Left Y for Background Box |
Integer |
BGBLRX |
Lower Right X for Background Box |
Integer |
BGBLRY |
Lower Right Y for Background Box |
Integer |
BGBULX |
Upper Left X for Background Box |
Integer |
BGBULY |
Upper Left Y for Background Box |
Integer |
BGBURX |
Upper Right X for Background Box |
Integer |
BGBURY |
Upper Right Y for Background Box |
Integer |
Bnd01 |
Boundary Point for PAV files, valid from 01 thru 99 |
Integer |
Bx1Int |
Box 1 Integral Value |
Float |
Bx1LLX |
Box 1 Lower Left X |
Integer |
Bx1LLY |
Box 1 Lower Left Y |
Integer |
Bx1LRX |
Box 1 Lower Right X |
Integer |
Bx1LRY |
Box 1 Lower Right Y |
Integer |
Bx1ULX |
Box 1 Upper Left X |
Integer |
Bx1ULY |
Box 1 Upper Left Y |
Integer |
Bx1URX |
Box 1 Upper Right X |
Integer |
Bx1URY |
Box 1 Upper Right Y |
Integer |
Bx2Int |
Box 2 Integral Value |
Float |
Bx2LLY |
Box 2 Lower Left X |
Integer |
Bx2LLY |
Box 2 Lower Left Y |
Integer |
Bx2LRX |
Box 2 Lower Right X |
Integer |
Bx2ULX |
Box 2 Upper Left X |
Integer |
Bx2ULY |
Box 2 Upper Left Y |
Integer |
Bx2URX |
Box 2 Upper Right X |
Integer |
Bx2URY |
Box 2 Upper Right Y |
Integer |
CentMX |
Center Cursor X Position |
Integer |
CentMY |
Center Cursor Y Position |
Integer |
CGain |
Camera Gain |
Float |
Colr1 |
Color 1 Value |
Text |
Colr2 |
Color 2 Value |
Text |
Colr3 |
Color 3 Value |
Text |
Colr4 |
Color 4 Value |
Text |
Colr5 |
Color 5 Value |
Text |
Colr6 |
Color 6 Value |
Text |
Colr7 |
Color 7 Value |
Text |
Colr8 |
Color 8 Value |
Text |
Colr9 |
Color 9 Value |
Text |
Colr10 |
Color 10 Value |
Text |
Colr11 |
Color 11 Value |
Text |
Colr12 |
Color 12 Value |
Text |
Colr13 |
Color 13 Value |
Text |
Colr14 |
Color 14 Value |
Text |
Colr15 |
Color 15 Value |
Text |
Colr16 |
Color 16 Value |
Text |
ComPrs |
Compression Type |
Text |
DGFld |
Digitizer Gamma setting (non-linear adj.) |
Float |
DiType |
Digitizer Type |
Text |
DPtNum |
Data Point Number |
Integer |
DSGain |
Digitizer System Gain |
Float |
DSOff |
Digitizer System Offset |
Float |
FldFrm |
Fields per Frame |
Integer |
FlorFr |
Field or Frame Data in this File |
Text |
FRate |
Frame Rate (frames/second) |
Float |
FrstCl |
First Color |
Integer |
EMFile |
Emissivity File |
Text |
IDFile |
Image Display Control File |
Text |
ImDisp |
Pre-digitized Image Display Format |
Text |
ImQual |
Image Quality |
Text |
ImSig |
Pre-digitized Image Signal Type |
Text |
ImSize |
Image Size (in bytes after any compression) |
Integer |
Intrlc |
Frame Data Are Interlaced in the File |
Text |
NClrs |
Number of Colors Used |
Integer |
PLeftX |
Profile Left X |
Integer |
PLeftY |
Profile Left Y |
Integer |
PRghtX |
Profile Right X |
Integer |
PRghtY |
Profile Right Y |
Integer |
ProCX |
Profile Cursor X |
Integer |
ProCY |
Profile Cursor Y |
Integer |
SpecFn |
Special Function to Apply to the Image |
Text |
SRFile |
Slant Range Correction Factor File |
Text |
VrtAtt |
Vertical Attitude (degrees) |
Float |
XMag |
X Compress or Enlarge Factor |
Float |
XPixls |
Digitized Data Image Width (pixels) |
Integer |
XPxWid |
X (horizontal) Pixel Width (meters) |
Float |
YMag |
Y Compress or Enlarge Factor |
Float |
YMax |
Maximum y value |
Float |
YMin |
Minimum y value |
Float |
YPixls |
Digitized Data Image Height (pixels) |
Integer |
YPxWid |
Y (vertical) Pixel Width (meters) |
Float |
Tag | Description | Data Type |
|---|---|---|
Calc01 |
Calculated Parameter, valid from 01 thru 99 |
Text |
FreRsp |
System Electrical Frequency Response (Hz) |
Float |
Keywrd |
XY File Keyword |
Text |
NParam |
Number of Parameters in File |
Integer |
NumDPs |
Number of Data Points in File |
Integer |
PcSize |
Parameter Classification Size (bytes) |
Integer |
PltSub |
XY Plot Subtitle |
Text |
PltTtl |
XY Plot Title |
Text |
PnSize |
Parameter Name Size (bytes) |
Integer |
PodOrd |
Data Ordering in POD Files |
Text |
PuSize |
Parameter Units Size (bytes) |
Integer |
SampRa |
Sample Rate (Hz) |
Float |
XCFile |
X-Axis Calibration File |
Text |
XDaUnt |
X-Axis Data Units |
Text |
XFName |
X-Axis Filename (a 1-parameter POD file) |
Text |
XParam |
X-Axis Parameter name |
Text |
XScFac |
X-Axis Scale Factor (applied to XFName values) |
Float |
XYFNum |
XY File Number |
Integer |
XYFrst |
XY First Value |
Float |
XYLast |
XY Last Value |
Float |
YParam |
Y-Axis Parameter name |
Text |
The following are the possible data types that can be stored in the DaType tag:
| ASCII | ASCII strings |
| Int8 | 1-byte integer (0-255 unsigned) |
| Int16 | 2-byte integer |
| Int32 | 4-byte integer |
| Int64 | 8-byte integer |
| Flt32 | Single-precision floating-point |
| Flt64 | Double-precision floating-point |
| RGB24 | 24-bit color image (3 bytes per pixel, RGB) |
KeyWrd tags can contain the following values:
Data Type | Tag Value | |
|---|---|---|
Image |
IMG |
2D array of values (the default tag value) |
|
CMAP |
2D array of colormap indices |
|
PAV |
Position and value triplets |
Parameter Oriented Data |
POD |
Multiple dependent parameters with the same independent parameter |
xy pairs |
XYPT |
(x,y) pairs, y vs. points |
|
XYFN |
(x,y) pairs, y vs. file number |
|
XYTM |
(x,y) pairs, vs. time |
|
XYDI |
(x,y) pairs, y vs. distance (in meters) |
y values only |
YPT |
y vs. points |
|
YFN |
y vs. file number |
|
YTM |
y vs. time |
|
YDI |
y vs. distance (in meters) |
|
YWL |
y vs. wavelength |
|
YWN |
y vs. wavenumber |
Files containing image data contain the tag KeyWrd, which is followed by one of the three types: IMG, CMAP, and PAV:
In IMG files, the header is followed by the image data, XPixls columns by Ypixls rows, and stored in row major order (row one, followed by row two, followed by row three, etc.). The file may contain more than one field; in this case, the image is assumed to be interlaced. A footer may be present following the image data and may contain information about background information (to be subtracted from the image during rendering or analysis) in the form of an array of single-precision floating-point numbers. Units are specified by values for StdUnt or DaUnit tags.
Following the header in CMAP files is a 768-byte palette, consisting of 256 RGB values. This is following by the image data stored as palette indices indexed from the beginning of the palette.
PAV files contain data in the form of ordered triplets, consisting of an ordered pair denoting position and another value related to amplitude. This is designed to enable a rendering application to generate a rectangular array of a size denoted by the values in the XPixls and YPixls tags. Origin is in the upper left corner of the image.
Ordered pair data consists of a list of data pairs in (x y) format. The second element of the pair is separated from the first by one or more spaces. Parameter names are stored in tags XParam and YParam, and units for x and y elements of the pair are stored in XDaUnt and DaUnit, respectively.
Data in (x y) format can also be stored as a list of singlet y data, with x values calculated from data stored in tags XYFIRST, XYLAST, and NumDPs.
Other types of files supported directly with predefined tags are Active Source Files and Parameter Oriented Data (POD) files. Please consult the documentation on the CD-ROM for more information on these types of data.
The following fragment should give you some idea of what a SAF file looks like. This is a uncompressed CMAP (palette) bitmap image file six pixels wide by six pixels high. The DaType of Int8 denotes byte size data. Note that at the time of this writing SAF supports only GZIP compression of image data (or none).
HdSize Auto Class Unclassified DaType Int8 Keywrd CMAP XPixls 6 YPixls 6 ComPrs NONE Data ff ff ff ab 0f 0d...[rest of 768-byte palette data]...00 00 00 00 00 01 fe 0d 0c bb 02 04 05 09 27 cc 0d 0a 23 21 22 41 de d2 c3 b9 02 aa ab ad 0a 09 32 cd 44 01 09 03 09
Information about the SAF format was kindly provided by Dave Holt, and you can reach him at:
Dale Holt
Sverdrup Technology
Arnold AFB, TN 37355
Email: holt@hap.arnold.af.mil
Consult the specification document on the SAF format included .
Copyright © 1996, 1994 O'Reilly & Associates, Inc. All Rights Reserved.
