DNG to PAM: conversion guide

What happens when you convert DNG to PAM?

RAW development

DNG needs camera- and file-aware development to produce a rendered PAM image. White balance, exposure, camera colour interpretation and, where applicable, demosaicing determine that rendering. The destination does not retain the original RAW development latitude. No development settings or camera support are implemented yet.

Transparency

The target can store an alpha channel, but converting an opaque image does not create transparent areas. Removing a background is a separate editing step.

Lossless sample storage

Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning. PAM can store its supported image samples without lossy compression. This applies after rendering and sample conversion: it does not guarantee preservation of source precision, colour space or document structure, and cannot undo earlier losses.

DNG

Source

DNG

Adobe Digital Negative

Compression: Depends on variantTransparency: NoMetadata: Exif, DNG tags

A published TIFF-based format for raw image data, calibration and photographic metadata.

Explore DNG format →

PAM

Target

PAM

Portable Arbitrary Map

Compression: UncompressedTransparency: YesMetadata: Header, Comments

Portable Arbitrary Map: simple uncompressed raster samples for image-processing pipelines.

Explore PAM format →

Is DNG → PAM right for you?

Good choice when

PAM fits your delivery use: Channel-aware image pipelines.
You need a developed image for a non-RAW application.
You need lossless storage of the rendered samples supported by PAM.
You can validate the destination’s sample precision and colour interpretation.
You need a PAM-compatible workflow that can hold transparency added in a separate edit.

Probably not when

You need the original sensor data and freedom to redevelop it.
You expect lossless encoding to restore lost details or editing structure.
You require identical samples without a defined colour and precision policy.
You expect automatic background removal or transparency.

DNG to PAM conversion details

RAW development: DNG needs camera- and file-aware development to produce a rendered PAM image. White balance, exposure, camera colour interpretation and, where applicable, demosaicing determine that rendering. The destination does not retain the original RAW development latitude. No development settings or camera support are implemented yet.
Transparency: The target can store an alpha channel, but converting an opaque image does not create transparent areas. Removing a background is a separate editing step.
Lossless sample storage: Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning. PAM can store its supported image samples without lossy compression. This applies after rendering and sample conversion: it does not guarantee preservation of source precision, colour space or document structure, and cannot undo earlier losses.
Sample precision & colour: Source and target sample models can differ in precision, channel layout, colour space and transfer function. Lossless compression only preserves the samples actually encoded; a precision reduction or colour conversion can already change them. The future engine defines numeric mapping, orientation and colour conversion; canonical depth facts are listed below where available.
Metadata & colour: Format support does not guarantee that an export preserves metadata or colour profiles. Retention and colour handling depend on the future converter; its engine is not implemented yet.
Compression: DNG: Depends on variant → PAM: Uncompressed DNG: Compression, sample type and processing stage are defined by the file and DNG version. Converting a proprietary raw file to DNG is different from exporting a rendered photo, but it does not guarantee preservation of every maker-specific feature. Keep the source when future reprocessing or vendor software matters. PAM: Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning.
Transparency: DNG: No → PAM: Yes
Colour depth: DNG: File-defined sample precision → PAM: maxval up to 65535
Sensor data: DNG: Raw development required
Dimensions: Pixel dimensions, page geometry, rendering resolution, resizing and orientation need explicit converter policies. The future engine has not defined them yet.
Metadata: DNG: Exif, DNG tags → PAM: Header, Comments. Which fields are copied, rewritten or omitted will depend on the future engine; retention is not implemented yet.

Common questions

Will PAM still be an editable camera RAW?

DNG needs camera- and file-aware development to produce a rendered PAM image. White balance, exposure, camera colour interpretation and, where applicable, demosaicing determine that rendering. The destination does not retain the original RAW development latitude. No development settings or camera support are implemented yet.

Will the background become transparent?

The target can store an alpha channel, but converting an opaque image does not create transparent areas. Removing a background is a separate editing step.

Does lossless output mean an unchanged source?

Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning. PAM can store its supported image samples without lossy compression. This applies after rendering and sample conversion: it does not guarantee preservation of source precision, colour space or document structure, and cannot undo earlier losses.

Are bit depth and colour values guaranteed to match?

Source and target sample models can differ in precision, channel layout, colour space and transfer function. Lossless compression only preserves the samples actually encoded; a precision reduction or colour conversion can already change them. The future engine defines numeric mapping, orientation and colour conversion; canonical depth facts are listed below where available.

Will metadata and colour profiles be retained?

DNG: Exif, DNG tags → PAM: Header, Comments. Which fields are copied, rewritten or omitted will depend on the future engine; retention is not implemented yet.

Explore related DNG and PAM conversions.