FF7/Field/Palette

From Final Fantasy Inside
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Section 4: Palette (Terence Fergusson & myst6re)

The following is an overview of the palette data.

Section 4 Format

Offset Size Description
0x00 4 bytes Length (Repeat of previous length header)
0x04 2 bytes PalX
0x06 2 bytes PalY
0x08 2 bytes Number of colors in palette
0x0A 2 bytes Number of palettes
0x0C (Number of palettes) * (Number of colors in palette) * 2 Palette data

After the first length indicator comes another integer, also indicating length. Useless, but it's there.
Then two bytes; palX, useful for the PS version only (always 0).
Then two bytes again; palY, useful for the PS version only (always 480).
Then two bytes; number of colors in the palette (always 256).
Then two bytes; number of palettes.
Then the actual palette data.

Each palette entry is a 16-bit color. This is unusual - normally palettes store as high quality data as possible, usually 24/32 bit. However since FF7 only ever runs in 16 bit I guess there isn't much point storing any other kind of data. Actually, the data is 15-bit (1 mask bit, 5-bit Blue, 5-bit Green and 5-bit Red).

Palette Data
Mask Blue Green Red (LSB)
m b b b b b g g g g g r r r r r

Palettes generally contain a number of colors that's a multiple of 256. This is because the palette is split up into 256-color 'pages' internally. So the first color is page 0/color 0. Color 256 is page 1/color 0. Color 628 is page 2/color 116. You'll see why in the background section.