GRFX - Revision history

Sembiance: software & samples

2025-06-13T07:01:22Z

software & samples

Jsummers: Category:Booting

2017-08-15T14:47:28Z

Category:Booting

Tekkno at 21:13, 12 January 2016

2016-01-12T21:13:05Z

Felix at 16:31, 19 March 2015

2015-03-19T16:31:03Z

Felix: new

2015-03-19T15:47:11Z

new

New page

{{FormatInfo
| subcat = Graphics
}}
'''GRFX''' is a raster graphics file format used for storing logos and splash screens in some AMI [[BIOS]]es.

== Structure ==
All number values are little-endian.

The file begins with this structure:
{| class="wikitable"
! Name !! Length and type !! Description
|-
| magic
| 4 bytes
| Always {{magic|'G' 'R' 'F' 'X'}}.
|-
| ???
| 2 bytes
| Unknown, usually {{magic|01 01}}.
|-
| hlen
| uint16_t
| Length of this header; usually 8.
|}

After this header, another structure follows.

{| class="wikitable"
! Name !! Length and type !! Description
|-
| ???
| 4 bytes
| Unknown; usually all zero.
|-
| hlen
| uint16_t
| Length of this structure. Always 78 (0x4e) in files known to this author.
|-
| ???
| 2 bytes
| Unknown; often zero, but {{magic|14 00}} and {{magic|2e 00}} are also known to this author.
|-
| ???
| 2 bytes
| Unknown; often zero, but {{magic|9f 00}} and {{magic|8c 00}} are also known to this author.
|-
| width
| uint16_t
| Image width in pixels.
|-
| height
| uint16_t
| Image width in pixels.
|-
| ???
| 2 bytes
| Unknown; probably a bitfield. Often {{magic|00 80}}, although {{magic|01 80}} and {{magic|03 80}} are also known to this author.
|-
| ???
| 2 bytes
| Unknown; often zero, although {{magic|0f 00}} is also known to this author.
|-
| colours
| uint16_t
| Number of colours. Always 16 in files known to this author.
|-
| ???
| 1 byte
| Unknown; always zero in files known to this author. Most probably just padding.
|-
| magic
| 3 bytes
| Always {{magic|'I' 'M' 'A'}} ("AMI" in reverse)
|-
| palette
| uint16_t [16 * 3]
| EGA palette; a series of triples of colour intensities of red, green and blue (in order), each in the range of 0 to 63.
|-
| ???
| 2 bytes
| Unknown; always zero in files known to this author.
|-
| ident
| 4 bytes
| Image identifier; four ASCII capital letters stored in reverse order. Common values are {{magic|'S' 'I' 'M' 'A'}} ("AMIS", small AMI logo) and {{magic|'L' 'I' 'M' 'A'}} ("AMIL", large AMI logo)
|}

After this structure, the bitmap data follows. Pixels are stored row by row, each row stores pixels left to right. Each byte contains data for two pixels; the more significant 4 bits store the left pixel of the pair.

It is not known to this author how the file format is supposed to behave for bitmap widths not divisible by two, or for palette sizes other than 16.

== Links ==
* [http://kannegieser.net/veit/programm/index_e.htm GRFX to PPM converter (with source code)]

@@ Line 89: / Line 89: @@
 It is not known to this author how the file format is supposed to behave for bitmap widths not divisible by two, or for palette sizes other than 16.
 == Links ==
@@ Line 95: / Line 99: @@
 == Samples ==
 * [http://kannegieser.net/veit/programm/index_e.htm GRFX to PPM converter (*.GRX)]
 [[Category:Booting]]

← Older revision		Revision as of 14:47, 15 August 2017
Line 98:		Line 98:
	== Software ==		== Software ==
	* [http://imageconverter.rest7.com/ Rest7 Online Image Converter]		* [http://imageconverter.rest7.com/ Rest7 Online Image Converter]
		+
		+	[[Category:Booting]]

@@ Line 83: / Line 83: @@
   | ident
   | 4 bytes
-  | Image identifier; four ASCII capital letters stored in reverse order. Common values are {{magic|'S' 'I' 'M' 'A'}} ("AMIS", small AMI logo) and {{magic|'L' 'I' 'M' 'A'}} ("AMIL", large AMI logo)
+  | Image identifier; four ASCII capital letters stored in reverse order. Common values are {{magic|'S' 'I' 'M' 'A'}} ("AMIS", small AMI logo) and {{magic|'L' 'I' 'M' 'A'}} ("AMIL", large AMI logo). Other spotted values are: NAYT, DSPD, GLMS.
   |}
@@ Line 92: / Line 92: @@
 == Links ==
 * [http://kannegieser.net/veit/programm/index_e.htm GRFX to PPM converter (with source code)]

@@ Line 17: / Line 17: @@
   | ???
   | 2 bytes
-  | Unknown, usually {{magic|01 01}}.
+  | Unknown; always {{magic|01 01}} in files known to this author.
   |-
   | hlen