A very old untility to convert GIF images to Nokia OTA Smart Message Images
During years 1998 to 2004 there was a craze for sending SMS that contained image and animation took over Iran. Most People had Nokia or Siemens phones which both supported OTA images, you could even include small animations that would span through maximum 3 SMS messages. People even would copy these images to their phone to brag to others. But something less known to most people was how easy they can make these images. I wrote this app to change gif images to OTA and give it to my friends (obviously at that time and only in black and white).
An OTA bitmap is used as part of the following Smart Messaging formats: Operator logo, CLI icon, Picture Message, and Downloadable Profile. In today's Nokia phones 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. Other information is defined there as well, but it handles issues that are not supported in today's Nokia phones. These values are similar in all OTA bitmap headers.
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.
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 pixels are also black 000000000000000000 000000000000000000 000000000000000000 000000000000000000 000000000000000000 000000000000000000 000000000000000000 000000000000000000 000000000000000001 <- Last pixel of this row/bitmap is black
For more information, please refer to the Smart Messaging Specification 3.0.0.