Which file format should you use for a medical-film photograph?
A good-looking image is not necessarily a faithful image, and a more complicated file format does not automatically make a photo medically reliable. Choose an export based on what the recipient can actually open, whether you need to preserve the original bytes and whether patient identifiers are visible. Here is how the current MedCam exports differ.
JPG: convenient for ordinary image sharing
JPEG pictures are widely accepted by phones and messaging apps. MedCam can create a JPG of the derived view; JPEG compression may discard some small image detail. A JPEG copied from a captured camera photo can also contain existing metadata such as orientation or location if the original file provided it. Avoid repeatedly editing and resaving a JPG if preservation matters. Keep the untouched original in addition to any converted picture.
PNG: a lossless encoding of the derived pixels
PNG encoding does not introduce JPEG-style compression artifacts into the derived pixel array. It does not, however, restore detail from a previously blurry or compressed photograph. A rotated, brightness-adjusted or perspective-corrected PNG is still a transformed image; it is not the original evidence. PNG can be larger than JPG, so check recipient file-size limits before sharing.
PDF: a page-shaped document, not better source data
PDF is useful when the receiving system expects a document rather than a photograph. In the current prototype, a selected image is embedded in a single-page PDF. This does not increase camera resolution or create a verified radiology report. Readable text may still be part of an image rather than searchable document text. Open the resulting PDF to inspect the image before sending it.
Experimental UMF: original plus processing history
The proposed UMF package is a ZIP-based container with the original image, an optional processed PNG copy, quality observations, transform history and file checksums. It is useful for evaluating a traceable workflow, but UMF is not a recognized international medical-imaging standard. Today's reference viewer only supports MedCam's documented subset. Many recipients will not have software to open the file. The proposed .umf suffix also needs collision and registration review before public standardization.
What about DICOM?
DICOM files generated by a medical imaging modality can contain study identifiers, imaging acquisition details, calibration and potentially multiple frames or series. Photographing a film sheet with a phone does not reproduce that source study. Renaming a photo as DICOM would be misleading. If a clinician needs original imaging data, request the study from the imaging facility rather than trying to substitute a phone photograph.
Patient privacy before export
A source image may contain patient names, record numbers, dates of birth or other sensitive information in the visible pixels or its embedded metadata. Re-encoding a processed JPG/PNG/PDF may omit source EXIF, but does not magically remove text visible in the photograph. MedCam's UMF package intentionally retains original bytes, including any metadata. Inspect the entire image and share only through appropriate channels with authorized recipients. Do not upload medical data to public file-hosting links unless you understand and accept that service's privacy practices.
A practical selection rule
When someone asks for an ordinary photo, first confirm whether they want the unmodified original or an adjusted copy, then choose an image format they can open. Choose PDF if the submission portal explicitly requires a PDF. Use an experimental UMF package only when the recipient has a compatible viewer and specifically needs the history and original. For treatment decisions, source radiology records and professional interpretation take priority over these convenience exports.
Open MedCam · UMF draft technical notes · Privacy and original metadata