Convert PDF to CGM

A legacy CAD, aerospace, defense, or technical-documentation system may accept CGM but not PDF. Converting the file can preserve vector drawings for that system, although PDF features such as transparency, annotations, and interactive content may be lost.

What the PDF format is

PDF is a page-description format used for manuals, forms, engineering drawings, scanned documents, and print-ready artwork. Adobe Acrobat, office suites, CAD programs, graphics editors, scanners, browsers, and publishing software can create PDF files.

A PDF page can contain vector paths, raster images, text, embedded fonts, clipping paths, transparency, annotations, forms, JavaScript, and other objects. The file stores a fixed page appearance, while the exact combination of objects depends on the application that created it. A conversion may therefore need to turn each PDF page into one CGM picture and flatten elements that CGM cannot represent.

What the CGM format is

CGM (Computer Graphics Metafile), standardized by ISO/IEC 8632, stores device-independent graphics commands for lines, curves, markers, text, filled areas, and raster elements. It is used in technical documentation, engineering drawings, mapping, manufacturing, aerospace, defense, and older publishing or visualization systems.

CGM can retain scalable vector geometry and can be smaller than a high-resolution bitmap. Compatibility depends on the receiving program's CGM version or profile, encoding, supported text features, color model, coordinate limits, and handling of embedded raster images. WebCGM is a related profile for interactive technical graphics, not a universal replacement for ordinary CGM.

How to convert PDF to CGM

Using CorelDRAW

CorelDRAW is suitable for occasional conversions that require visual inspection and manual correction. The exact menu names and available CGM profiles vary by version.

1. Open or import the PDF with File → Open or File → Import.
2. Select the required page and choose editable-object import when available. Do not choose a page-as-image option unless the source is already rasterized or editable geometry is unnecessary.
3. Inspect fonts, line weights, dimensions, fills, clipping, transparency, page orientation, and colors. Replace missing fonts or convert critical text to outlines before export; keep an editable source copy.
4. Use File → Export, select CGM - Computer Graphics Metafile, and choose the CGM encoding or profile required by the destination system.
5. Open the resulting .cgm file in the target application and check a known dimension, text placement, line widths, colors, and orientation.

For multipage PDFs, export pages individually if the receiving application expects one CGM picture per file. CGM implementations differ in their support for multiple pictures within one metafile.

Using command-line conversion

For repeatable jobs, Poppler and pstoedit provide a practical open-source workflow. Install both from official packages or a trusted operating-system repository, and confirm that the pstoedit build contains a CGM driver.

pdftops -f 1 -l 1 input.pdf page.ps
pstoedit -f cgm page.ps page.cgm

pdftops -f 1 -l 1 writes only page 1 to PostScript; change both page numbers for another page. pstoedit -f cgm selects the CGM output driver. Check available drivers with pstoedit -f help. Some pstoedit builds can read PDF directly, but the PostScript intermediate makes page selection explicit and exposes conversion failures earlier.

Review the output in the target system rather than relying on successful command completion. Unsupported transparency, clipping, fonts, patterns, gradients, or blend modes can be converted inaccurately or rasterized.

Using an online converter

For an occasional, nonconfidential file, a reputable service such as Convertio or Zamzar can be used when its current format list offers PDF-to-CGM. Upload the PDF, select CGM, start the conversion, download the result, and test it in the destination program. Online services may impose page and file-size limits, and their available settings can be less precise than desktop software.

Do not upload proprietary drawings, personal records, export-controlled material, or files containing sensitive metadata unless the service has been approved for that data. Remote processing also means the result may be retained temporarily under the provider's stated policy.

Quality and compatibility limits

• Vector preservation is not guaranteed. A vector PDF normally converts more cleanly than a scan, but transparency, masks, blend modes, gradients, patterns, live effects, and embedded 3D objects may be flattened, discarded, or rasterized.
• Scans remain raster images. Conversion cannot reconstruct the original lines or text geometry. Export the page at an adequate resolution, then place the raster in a CGM file only if the receiving system supports CGM raster elements.
• Text can change. CGM viewers may lack the embedded PDF fonts, Unicode shaping, OpenType features, or text-on-path support. Install compatible fonts or outline critical text, and verify labels after conversion.
• Scale requires verification. Compare a known dimension after import. Set the target application's units, page size, and picture scale explicitly because CGM consumers may apply different metric units or coordinate limits.
• Color may differ. PDF can contain ICC-managed RGB, CMYK, spot colors, and transparency; a CGM implementation may support only a smaller indexed or device-oriented color range.
• Interactive PDF content is not preserved. Links, annotations, forms, JavaScript, layers with application-specific behavior, and embedded media generally have no equivalent in a static CGM picture.