PIC — Palettized Image (.PIC)¶

Custom image format used for aircraft skins, HUD overlays, instruments, and backgrounds. Three sub-formats share the same 64-byte header, identified by the format field. Stored throughout the .LIB archives — FA_2.LIB carries the in-game art, FA_3.LIB the encyclopedia photographs.

Tools¶

fx¶

fx pic info   <file.PIC>                # header and sub-format summary
fx pic unpack <file.PIC> [-o out.png]   # decode to PNG
fx pic pack   <file.png> [-o out.PIC]   # re-encode (see Round-Trip Notes)

Other Tools¶

GIMP — free, cross-platform; handles indexed-color and palette-aware editing well
Paint.NET — free, Windows; simple and fast for texture touch-ups
Photoshop $ — industry standard; use 8-bit indexed mode to stay within palette
Affinity Photo $ — one-time purchase alternative to Photoshop

File Layout¶

All multi-byte integers are little-endian.

PIC codec modes: a common 64-byte header whose format field selects dense row-major pixels with a row-head table, sparse 10-byte span records, or a whole-file JPEG; the palette is inline or the system PALETTE.PAL, and index 0xFF is transparent

Header (64 bytes)¶

Offset	Size	Type	Description
`0x00`	2	u16	format: 0=dense, 1=sparse, 0xD8FF=JPEG
`0x02`	4	u32	width in pixels
`0x06`	4	u32	height in pixels
`0x0A`	4	u32	pixels_offset (absolute file offset of pixel data)
`0x0E`	4	u32	pixels_size
`0x12`	4	u32	palette_offset (absolute file offset of inline palette, 0 if none)
`0x16`	4	u32	palette_size (0 if using system PALETTE.PAL)
`0x1A`	4	u32	spans_offset (format=1 only)
`0x1E`	4	u32	spans_size (format=1 only)
`0x22`	4	u32	rowheads_offset (format=0 only)
`0x26`	4	u32	rowheads_size (format=0 only; must equal 4 × height)
`0x2A`	4	u32	font_data_offset — offset of a trailing 1,536-byte glyph-metrics block (256 × 6-byte records); nonzero only in the `FNT`/video-title PICs. Not read by FA.EXE's PIC path* (offline/FNT-DLL metadata) — see Round-Trip Notes
`0x2E`	18	u8[18]	Padding, zeroed

Pixel Data¶

One byte per pixel — each byte is a palette index (0–255). Index 0xFF = transparent.

Palette¶

The inline palette at palette_offset (if palette_size > 0) is raw VGA 6-bit data: palette_size / 3 RGB triplets, each channel in range 0–63.

Scale to 8-bit: actual = (stored << 2) | (stored >> 6) (rotate-left-2).

If palette_size == 0: the PIC uses the system PALETTE.PAL.
A partial palette (palette_size < 768) overrides only the first palette_size/3 entries.

Format 0 — Dense / Texture¶

Pixel data is sequential, row-major (top to bottom, left to right): width × height bytes.

A row-head table at rowheads_offset contains height u32 values, each the absolute file offset of the start of that row. Must be reconstructed correctly when encoding:

rowheads[y] = pixels_offset + y * width;

Used for aircraft skins, terrain tiles, full-screen images.

Format 1 — Sparse / Image¶

Used for HUD overlays and UI elements where most pixels are transparent.

spans_offset points to an array of 10-byte span records, terminated by row = 0xFFFF:

Offset	Size	Type	Description
`+0x00`	2	u16	row index
`+0x02`	2	u16	start column (inclusive)
`+0x04`	2	u16	end column (inclusive)
`+0x06`	4	u32	byte offset into pixels_data for this span's pixels

Pixels per span: end - start + 1.

Format 0xD8FF — JPEG¶

The entire .PIC file content is a standard JPEG — pass it directly to a JPEG decoder. All PIC files in FA_3.LIB are this format. These are encyclopedia reference images (photographs, diagrams), not the 3D aircraft skin textures (which use format 0 and carry the _ prefix in FA_2.LIB).

File Inventory¶

Filename Conventions¶

The filename prefix identifies the role of the image within the engine:

Prefix	Role	Example
`$`	2D weapon / ordnance cockpit icon	`$AIM9M.PIC`, `$AGM65A.PIC`
`_`	Aircraft skin / texture (referenced by `.SH` `TextureFile` instruction)	`_A10.PIC`, `_KIN.PIC`
(none)	All other images: UI, medals, backgrounds, terrain tiles	`PALETTE.PIC`, `ATFSPLAS.PIC`

The $ and _ prefixes are engine conventions embedded in the filenames stored in the .LIB archives. They have no effect on the file format itself.

FA_3.LIB Naming Convention (Encyclopedia Reference Images)¶

FA_3.LIB (Disc 2) contains 700+ JPEG-format PIC files used by the in-game aircraft encyclopedia viewer. All are 512×384 pixels except the five bare-name thumbnail files (640×480). They are never referenced by the 3D engine.

Numeric suffix <AC>_<N>.PIC (N = 0–9) — exterior photographs and action shots of the aircraft, one image per slot. Most aircraft have 4–10 numeric variants. The game cycles through them in the encyclopedia photo gallery. Simple or uncommon aircraft may have only _0. Count: 678 files.

Letter suffixes:

Suffix	Role	Count	Example
`_C`	Cockpit interior photograph	48	`F14_C.PIC`, `F22_C.PIC`
`_E`	Engine photograph or cutaway	38	`F14_E.PIC`, `F22_E.PIC`
`_P`	Profile diagram with callout labels	37	`F14_P.PIC`, `F22_P.PIC`
`_F`	Internal structure / systems cutaway (CAD/exploded view)	16	`F22_F.PIC`, `F16C_F.PIC`

_F is present only on higher-profile or more technically complex aircraft: AF1, ASTOVL, AV8, B747, CMCHE, E2000, E3, F117, F16C, F22, F260, F29, F31, GRIPEN, RAFALE, V22.

Bare name <AC>.PIC (no suffix) — five files (A6, F15, F15J, F18C, TU160) at 640×480 pixels. These are aircraft selection screen / hangar thumbnails. The aircraft image is composited against a white background. All other aircraft use the _0 exterior photo in contexts where a thumbnail is needed.

Round-Trip Notes¶

fx pic repack re-emits any PIC byte-identically from its parsed structure: the header fields are re-serialized (proving them), the 22-byte header tail at 0x2A–0x3F is carried verbatim, and every region is copied through at its recorded offset under full-coverage verification — an unaccounted or overlapping byte fails the repack rather than being silently copied. Validated against every PIC in the full install (census in tests/test_pic.cpp; 2,693 dense + 493 sparse, no JPEG PICs ship inside the LIBs).
Layout facts established by the whole-install census (inferred): dense = header · pixels (width×height at 64) · row-heads (4×height) · optional 768-byte palette, with spans_offset = 0 and a vestigial spans_size the engine never reads (commonly 10×(height+1); the font PICs carry another image's stale value). Sparse = header · pixel runs · span table · optional palette, the span table 16-byte aligned over short all-zero padding. Font PICs end with a trailing 1,536-byte block (256 × 6-byte glyph records) named by header field 0x2A (below), also 16-aligned.
font_data_offset (0x2A) is not consumed by FA.EXE's PIC path. The .PIC name-resolution and list paths (?FindPic@@YGXPAD0JJ@Z 0x467C30, _MakePicList@16 0x4679C0) and every .PIC string consumer were traced; none dereference header offset 0x2A. Consistent with runtime fonts being served by the FNT overlay DLLs, the field is offline glyph-metrics metadata (nonzero only in the 25 *FNT/title PICs per the #175 census), carried verbatim through repack but never read by the base executable.
fx pic pack (PNG import) always encodes as format=0 (dense) with a full inline palette. The game accepts format=0 in place of any sub-format, including JPEG originals; use repack when byte identity matters.
Keep image dimensions unchanged — the engine does not resize at load time.
Pixels are quantized to the nearest palette color on re-encode; alpha < 128 maps to 0xFF.

Formats: PAL — the system palette and the 6-bit color encoding; LIB — container for every PIC; SH — 3D shapes reference _ textures via their TextureFile instruction.