JEF file format explained: the Janome colour chart, hoop codes and what JEF+ adds

JEF is Janome's stitch format and the one Elna machines share. It is simpler than PES, has one quirk that catches people every week, the hoop code, and a colour system that turns every design's thread list into Janome's own chart.

Layout

A JEF file starts with a 116-byte header of little-endian integers: the offset of the stitch data, a version, a date string (20260910120000 style), a colour count, a stitch count, a hoop code, then a set of rectangles that describe the design's extents in the hoop. After the header come the colour table (one four-byte index per colour), a table of thread types (usually 0x0D for every entry), and the stitch stream.

Stitches are two bytes each, signed x and y in 0.1 mm units, range −127 to +127, so 12.7 mm per record. Commands are marked by 0x80 in the first byte: 0x80 0x02 is a jump (the next record is the move), 0x80 0x01 a colour change, 0x80 0x10 the end. Trims are not separate commands; Janome machines trim on a jump according to their own setting.

The viewer decodes all of this and shows the hoop code from the header alongside the design size, which is the first thing to check when a machine refuses a file.

The hoop code

Offset 24 in the header is a number that names a hoop:

| Code | Hoop | Field | |---|---|---| | 0 | A | 110 × 110 mm | | 1 | B | 140 × 200 mm | | 2 | C (small) | 50 × 50 mm | | 3 | F, later SQ/RE | 126 × 110 mm | | 4 | Giga / SQ20 | 200 × 200 mm |

Later machines added codes for the SQ14, RE20, RE28 and GR hoops; Janome's software writes the code for the hoop selected on export. Machines from the MC300E era compare the code against the hoop attached and refuse a mismatch outright. Newer models (MC500E, 550E, Continental) are more forgiving: they check the design's size against the field and only warn about the code.

So the classic "does not fit" on a design that measures 90 × 90 mm is a code that names a larger hoop than the one you have on. The fix is to re-save with the right code, which any converter that writes JEF can do. Our writer sets the code from the design's size: the smallest of the standard hoops the design fits in, with 3 mm clearance, so an A-hoop design gets code 0 and a 130 × 180 mm design gets code 1. The hoop fit checker shows which Janome hoop a design fits before you convert.

The 79-colour chart

JEF stores each colour as an index into Janome's thread chart: 1 is black, 2 white, 3 sunflower, up to 78 or 79 depending on the software version. There is no RGB and no thread name. Software writing JEF from a design in another brand picks the nearest Janome entry for each colour; the machine shows that name (and its RGB approximation) on screen.

The mapping is one-way, and it groups colours: two nearby shades of blue in Isacord often land on the same Janome entry, which does not affect stitching but makes the on-screen colour list shorter than the colour sheet. Keep the designer's sheet as the source of truth and use the thread converter when you need to cross-reference the chart against what you stock.

JEF+ and JPX

Janome's Digitizer software saves JEF+ (extension .jef+) and later JPX. Both wrap a standard JEF stitch section with an object layer, a background image and editing metadata. A machine that reads JEF reads the stitch section of either. When a shop sells "JEF+" and your machine wants JEF, the stitches are the same; rename or re-save if the machine does not accept the extension.

Converting to and from JEF

Into JEF. Stitches, jumps and colour changes carry over from any format. Colours are re-mapped to the chart. Trims become jumps (Janome trims on them). The hoop code is set from the size. Designs larger than 200 × 280 mm need the RE28 or GR code, which the writer sets; a design wider than any Janome field gets the largest code and the machine will refuse it, which is correct.

Out of JEF. To PES, colours go from Janome's chart to Brother's palette, a second approximation. To DST, colours are dropped. To VP3, the Janome names are written as thread names with the chart's RGB, which Husqvarna software shows correctly. The PES to JEF page lists the specific losses for that pair, the commonest one.

Reading a problem JEF

1. Open it in the viewer. Check the size and the hoop code shown in the header panel.
2. If the machine refused it: compare the hoop code with your frame. Re-save with the right code.
3. If the colours look wrong: they are the chart's approximations. Read the colour sheet.
4. If it stitches with loose threads between elements: the design's jumps are longer than the machine's trim threshold. Cleanup adds trims before long jumps.
5. If it will not open at all: the file may not be a JEF. The viewer identifies the format by its contents, not the extension.