PXL (Pixel Image Data)

Indexed-color image data of the sprite editor.

PXL (Pixel Image Data)
Extension	.PXL
ID	0x11

Overview

The PXL format stores 4-bit or 8-bit indexed-color images created and edited by the PlayStation sprite editor. Palette information is not included, because it is held in a CLT file that is used together with the PXL file. The format has a simple header with an ID field and a FLAG field, which is followed by the raw pixel data.¹

All values are stored in little-endian format. The bytes of a 16-bit or 32-bit value are therefore stored in ascending order, so a 32-bit value is stored as byte 0, byte 1, byte 2 and then byte 3.¹

ID

The ID field is a 32-bit value with the following bit definition:¹

Table 1: PXL file header
Bits	Field	Value
0..7	ID	0x11
8..15	Version No.	0x00
16..31	Reserved	All zero

FLAG

The FLAG field is a 32-bit value that describes the pixel data format. Bit 0 (PMODE) is the pixel mode, 0 for 4-bit CLUT and 1 for 8-bit CLUT. The other bits are reserved and zero.²

Pixel Data

The pixel data section has a short header followed by raw image data that is ready to be copied to the VRAM of the PlayStation:²

Table 2: Pixel data section
Field	Contents
bnum	Length of the pixel data in bytes, including the 4 bytes of bnum
DX	Frame buffer x coordinate
DY	Frame buffer y coordinate
W	Size of the data in the horizontal direction
H	Size of the data in the vertical direction
DATA	VRAM data (16 bits)

The structure of one 16-bit item depends on the mode. In 4-bit mode it holds pix0 to pix3 from the LSB, and in 8-bit mode it holds pix0 and pix1. The pixels appear on the screen in that order starting from the left. In 16-bit mode an item holds R, G and B in 5 bits each and the STP bit in bit 15.³

The VRAM coordinate system is based on 16 bits per pixel, so care is needed with the coordinate and size values. In the X direction one VRAM pixel holds 4 pixels in 4-bit mode and 2 pixels in 8-bit mode. Consequently the image width must be a multiple of 4 in 4-bit mode and an even number in 8-bit mode.³

References

^ ^a ^b ^c Sony Computer Entertainment Inc. File Formats. November 1998. Page 3-11, Figures 159 to 161.
^ ^a ^b Sony Computer Entertainment Inc. File Formats. November 1998. Page 3-12, Figures 162 and 163.
^ ^a ^b Sony Computer Entertainment Inc. File Formats. November 1998. Page 3-13, Figure 164.

Categories: File formats