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File Format Conversion in Essential FTIR
The software programs offered by most instrument companies support undocumented, proprietary file formats. These programs usually offer few options for exporting the data into more universal, open formats. When they do offer export options, it usually has to be done on one file at a time because there is no provision for batch conversion of groups of files.
Converting files is as easy as choosing the 'Batch File Conversion' tool in eFTIR, selecting the source files, choosing the format to convert to, and choosing a destination. One file, or entire folders of files, can be converted with a few clicks of the mouse.
Files can be converted from any of the file types that eFTIR can read. The formats that eFTIR can write to are:
Thermo/Galactic (.spc) format. This is the format created and used by Galactic in its popular SpectraCalc, LabCalc and GRAMS programs. Despite its age (dating to about 1988) and limitations, it has become a defacto common file format in the industry and can be read by most infrared spectroscopy software. The format is well documented, and a Software Development Kit is available here: https://ftirsearch.com/features/converters/spcfileformat.htm. Galactic released a free ActiveX component named gspciolib.dll for reading .spc files in your own programs, but it seems to have disappeared from the internet after the Thermo acquisition of Galactic. The dll was packaged with documentation and named ‘SpcIO Library’.
A variant of .spc format is the ‘Spectra-Calc fixed point’ format. Before the .spc format supported floating point numbers, it used a fixed point notation. This format is supported by eFTIR at the request of a few customers who have custom programs that only support this way of handling data.
JCAMP-DX files (.dx, .jdx). This is the JCAMP Data eXchange format, which was created in the 1980s. Designed to be flexible and extensible, it is an ASCII format so it is human-readable. It includes some clever compression options because disk space was a scarce resource in the 1980. Because the compression options make it unreadable, and limited disk storage space is no longer a problem, most JCAMP files that one encounters are uncompressed. This format is well documented, see www.jcamp-dx.org, and supported by many spectroscopy programs
ASCII. These is plain text including the format known as comma-separated-values (.csv). These are human readable tables of spectral values. The format is well-supported, and human-readable, but has many limitations. Most importantly, any supplemental ‘header’ information, such as memo fields, data types, audit trails, and so on, is not transmitted in this format.
Excel (.xls). This is the popular Microsoft Excel spreadsheet format. eFTIR can write directly to this format. Excel is used by many scientists for data analysis.
Matlab (.mat). In the 1990’s, Matlab became the default program for chemometrics development. eFTIR can write directly to this format, making data interchange easy for the matlab user.
Perkin-Elmer (.sp) file format. Support for this PE format allows data interchange with Perkin Elmer software packages.
Essential FTIR can also combine multiple spectra into what are known as multi-files, which are single files that contain multiple, related, spectra. This ability is very useful for those who are developing chemometrics applications, because all of the needed data is packaged into one file. The ‘Export to Multifile’ tool in eFTIR performs this action.