DGT data format

■ File layout

offset	size	function
$ 000	$ 100	header
$ 100	$ 20	directory
$ 120	variable	CLUT (color look-up table)
Indefinite	variable	Bitmap data

◆ Header

offset	size	Explanation
$ 00	word	Header size = $ 100
$ 07	Part-Time Job	Number of directory entries = $ 01
$ 08	Long	File size excluding header
$ 10	$ 10	Identifier = "DIGITIZER_3_Ver2" ("_" is a space = $ 20)
$ 20	$ E0	Dummy data, all $ 00

◆ Directory

offset	size	Explanation
$ 00	Long	Directory size = $ 20 + CLUT size (variable)
$ 04	word	Horizontal display position (usually $ 0000)
$ 06	word	Vertical display position (usually $ 0000)
$ 08	word	Horizontal image size
$ 0A	word	Vertical image size
$ 10	$ 10	Dummy data (all $ 00)

● The free address of "Directory name" is $ 20.

● All free addresses except "directory name" are $ 00.

◆ CLUT

Exists in palette mode and run length mode.

offset	size	function
$ 00	Long x number of pallets	CLUT data

● One palette is composed of "long x 16 colors".

● If even one color is used, one palette of data will be secured.

CLUT data

MSB　
│ │ Palette number　
┌─┼─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐
│ * │ E │ D │ C │ B │ A │ 9 │ 8 │ 7 │ 6 │ 5 │ 4 │ 3 │ 2 │ 1 │ 0 │
└─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘

│ Color data LSB
│ │ B │ G │ R │ B │ G │ R │
┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐
│ * │ 0 │ 0 │ 0 │ 4 │ 3 │ 2 │ 1 │ 4 │ 3 │ 2 │ 1 │ 4 │ 3 │ 2 │ 1 │
└─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘
* = Unused

● The color code is $ FFFF for palette numbers that are not used on the bitmap data even if there is a CLUT. This allows you to find out which palette numbers are not in use from the CLUT.

◆ Bitmap data

offset	size	function
$ 00 ~	Word x image size	Palette number for each pixel

★ Graphic Tools Guide ★ Format list