What is a JPM File?
A JPM file uses the JPEG 2000 compound-image format to represent multi-page or mixed-content documents. It can combine raster elements with structural and layout information in one file.
How JPM Files work
JPM is the compound image file format of JPEG 2000 Part 6. It extends JP2, reuses boxes from JP2 and JPX, and follows the mixed raster content model. A file is a sequence of pages, and each page is built from a base page, which is transparent or filled with a single color, plus layout objects applied in order. A layout object normally pairs an image object with a mask object: the mask is a single-component opacity image that controls where the image shows through, and mask and image typically have different resolutions. This lets bi-level detail such as text and line art use one kind of coder while photographic regions use another. Page collections group pages for navigation, and pages, layout objects, and their mask and image objects can carry labels and metadata. In a scanning workflow, validation must cover page structure and every coder the file uses, not merely confirm that a JPEG 2000 decoder is present.
Key facts
- JPM is defined by JPEG 2000 Part 6 (ISO/IEC 15444-6, published by ITU-T as T.805) as an extension of the JP2 file format. Its recommended extension is
.jpmand its registered media type isimage/jpm. It starts with the same 12-byte signature as every JPEG 2000 family file, so the File Type box brand,jpmplus a space, is what distinguishes it from JP2. - A JPEG 2000 decoder alone may not be enough. Mask and image objects can use other coders, and the mandatory compound image header box lists which mask coders and image coders a file may use. The specification’s web profile, for instance, allows MMR, JBIG2, or JPEG 2000 for masks and JPEG or JPEG 2000 for images.
- A reader that only understands JP2 does not get the pages. When a JPM file is JP2 compatible, the JP2 header box and the first contiguous codestream describe a document-level thumbnail, so a JP2 decoder that opens the file shows that thumbnail, not the composed page images.
- One
.jpmfile is not always the whole document. Images and data may be referenced in external files; the compound image header carries a self-contained flag and a page count, stored as 0 when unknown, that an ingest step can check before moving or archiving the file.
When JPM Files matter
Scanning and archival systems may choose JPM when several document elements must remain packaged together. General image viewers may not support its compound structure, so compatibility requires testing.
How Transloadit helps with JPM Files
Transloadit’s supported image formats table lists JPM as readable and writable in both documented ImageMagick stacks, for the /image/resize, /image/enhance, and /document/thumbs Robots. The entry is described as JPEG-2000 File Format Syntax, the same description the table gives JP2.
The table records format-level read and write support only. It does not say whether the pages, layout objects, masks, or non-JPEG-2000 payloads of a compound JPM file are interpreted, and ImageMagick’s source registers JPM under its JP2 coder. Test a representative multi-page file before depending on it.
Explore Transloadit’s file formats & compression capabilities