PS to CH Converter

PS to CH Conversion Explained

Converting .PS to .CH is a highly specialized data recovery process. It transforms a visual document format (PostScript) into a raw scientific data format (Chromatography data). Users convert .PS to .CH to recover lost analytical data when the original instrument files are missing, but a digital print spool or report remains.

This conversion extracts 2D vector paths from the .PS file, maps them to X and Y axes (usually time vs. absorbance), and digitizes them into an array of raw data points. You gain the ability to re-integrate peaks and analyze legacy data in modern chromatography software. However, you lose exact numerical precision, instrument metadata, and audit trails.

If your .PS file is a Program Stream video file (MPEG-PS) from a DVR, converting it to .CH is impossible and serves no purpose. Video frames do not contain chemical sensor data. This conversion only applies to PostScript documents containing plotted chromatograms.

Typical Tasks and Users

• Analytical Chemists: Recovering legacy High-Performance Liquid Chromatography (HPLC) or Gas Chromatography (GC) data for re-analysis.
• Data Scientists: Digitizing historical chemical reports to train machine learning models on large datasets.
• Laboratory Managers: Migrating old archives where raw data was purged, but .PS print spools were saved.
• Quality Control Auditors: Comparing historical printed baselines against modern integration algorithms.

Software & Tool Support

Very few tools handle this conversion natively due to the format mismatch. Users typically rely on a chain of software:

• Handling .PS files: You can view and parse PostScript files using Ghostscript, Adobe Acrobat, or vector editors like Inkscape.
• Handling .CH files: Chromatography files are opened using vendor software like Agilent OpenLab or open-source platforms like OpenChrom.
• Manual Conversion Tools: Researchers often use WebPlotDigitizer to manually extract data points from a rendered .PS file and export them to CSV, which is then converted to a .CH or AIA/ANDI format via custom Python scripts.

Pros and Cons of the Conversion

Pros:

• Data Resurrection: Allows you to salvage raw data from static documents.
• Re-integration: Enables modern software to apply new baseline algorithms to old runs.
• Storage Efficiency: A raw .CH data array is often smaller than a complex .PS document containing embedded fonts and logos.

Cons:

• Fidelity Loss: PostScript stores Bézier curves and line segments. Sampling these curves introduces rounding errors compared to the original detector signal.
• Metadata Stripping: Instrument parameters, injection volumes, and column temperatures are lost unless manually parsed from the text.
• Compliance Issues: Reconstructed .CH files lack original cryptographic signatures and fail Good Laboratory Practice (GLP) audit trails.

Conversion Difficulties & Why Convert.Guru

The technical pipeline to convert .PS to .CH is complex. A standard converter cannot simply transcode the file. The system must parse the PostScript code, ignore text and gridlines, isolate the specific vector path representing the chromatogram, and sample data points along that path at regular intervals. It must then read the axis labels to scale the data correctly before encoding it into the proprietary binary structure of a .CH file.

Convert.Guru simplifies this process. Instead of requiring users to manually render the .PS file, crop the image, and use a plot digitizer, Convert.Guru automates the vector-to-array extraction. It handles the coordinate mapping and outputs a structured .CH file ready for import into chromatography data systems, minimizing manual error.

PS vs. CH: What is the better choice?

Which format should you choose?

You should keep files in .PS if your goal is archiving the exact visual layout of a laboratory report, or if you need to send the document to a printer.

You should choose .CH if you need to perform quantitative chemistry, integrate peaks, or compare runs using analytical software. You should avoid converting .PS to .CH if you require strict regulatory compliance, as the digitized data is an approximation and cannot replace original raw instrument data in a legal or audited environment.

Conclusion

Converting .PS to .CH makes sense only as a last-resort data recovery method for legacy chromatograms trapped in print files. The biggest limitation is the inherent loss of exact detector precision and audit metadata during the vector-to-array translation. For users who must recover this data without writing custom Python parsing scripts, Convert.Guru provides a reliable, automated pipeline to extract the signal and format it into a usable .CH file.