Batch conversion fails when every file is treated as a one-off. Define the input contract, output naming, quality gates, and exception path before processing volume. A small number of predictable steps is more reliable than an automated workflow with no review boundary.
Write an input contract
Specify accepted formats, minimum dimensions, expected background, transparency rules, and cases that require a person. Separate clean line art from photographs and already-vector PDFs because they require different handling.
Verify
- List supported file types and size limits.
- Define when manual tracing is required.
- Keep rejected inputs with a reason code.
Standardize naming and metadata
Create filenames that preserve the original identifier, conversion version, output format, and review state. Store the source checksum or another stable reference. Do not overwrite the only copy when a new threshold or cleanup pass is tested.
Verify
- Use a consistent separator and ordering.
- Reserve suffixes such as draft, reviewed, and rejected.
- Keep settings beside each accepted output.
Apply objective quality gates
Check that the file opens, contains real paths, has usable dimensions, and does not depend on missing raster resources. Compare a scaled preview with the source and inspect node count for suspicious explosions. Route failed files to a human rather than silently accepting them.
Verify
- HTTP or file-open check for basic integrity.
- Embedded-image and path-content inspection.
- Visual comparison at native and enlarged scale.
Review exceptions and version outputs
Keep a short queue of files with broken counters, disconnected lines, excessive nodes, or ambiguous colors. Record the manual correction and promote only reviewed files to final. Re-run the batch only for the failed subset when settings change.
Verify
- Log exception type and resolution.
- Promote reviewed outputs to a separate final directory.
- Retain the prior version until acceptance is confirmed.
Common failure modes
- Do not automate conversion without a definition of a failed output.
- Do not overwrite source files or earlier reviewed versions.
- Do not treat a successful download as proof that every file passed visual review.