Appendix "A1" - Message types - OTA bitmap

Introduction

An OTA bitmap is used for various SMS formats: Operator logo, CLI icon, Picture Message, and Downloadable Profile. In most phone the maximum size of the operator logo and the CLI icon is 72 x 14 pixels, while the maximum size of the picture message and the screen saver is 72 x 28 pixels. An OTA bitmap consists of a bitmap header and bitmap data. The size of the bitmap is specified in the header.

A typical OTA bitmap (72 x 14 pixels) header is: 00480E01

00

Infofield

48

Width of the bitmap is 72 pixels

0E

Height of the bitmap is 14 pixels

00

Number of colors or grey shades (only one color)

The image data is located after the header information and is encoded as follows. Each semi-octet in the OTA bitmap presents 4 pixels in the original bitmap. Because one row takes 18 semi-octets, the whole 72 x 14 (operator logo and CLI icon) bitmap takes 18 x 14 = 252 semi-octets = 126 octets. With picture message and screen saver, the entire 72 x 28 size bitmap takes 18 x 28 = 504 semi-octets = 252 octets. For example, if the first four pixels of the image are 1010 (1 - black, 0 - white), the first semi-octet of the OTA bitmap data is hex A.

Example

Here is an example of a simple OTA bitmap (72 x 14 pixels). In the picture, there are two black lines and several black dots:

FFFFFFFFFFFFFFFFFF <- First line black
000000000000000000 <- Second line white
FFFFFFFFFFFFFFFFFF
000000000000000000
10F000000000000000 <- Fourth pixel of this line is black and 9-12
000000000000000000 pixels are also black
000000000000000000
000000000000000000
000000000000000000
000000000000000000
000000000000000000
000000000000000000
000000000000000000
000000000000000001 <- Last pixel of this row/bitmap is black

More information