rfc478155b.txt





    Cover Sheet for the Tiny Bitmap Specification


    Due to the low quality Internet connections in Poland, we set out to define
	an image format for really small images.  This way Polish internet users
	will have glorious loading times for web pages using this new and superior
	format. 

    APPLICATION EXTENSION BLOCK - APPLICATION IDENTIFIER

    There will be a Courtesy Directory file located on InfoPolska in the PICS
    forum.  This directory will contain Application Identifiers for Application
    Extension Blocks that have been used by developers of TBF applications.
    This file is intended to help keep developers that wish to create
    Application Extension Blocks from using the same Application Identifiers.
    This is not an official directory; it is for voluntary participation only
    and does not guarantee that someone will not use the same identifier.

    E-Mail can be sent to Szymon Zieliński (forum manager of PICS) indicating the
    request for inclusion in this file with an identifier.









































                               TINY BITMAP FORMAT

                                  Version 0.1b

                                    (c)1975

                                   Copyright
                            InfoPolska Incorporated
                               Bydgoszcz, Poland






























InfoPolska Incorporated                                    Tiny Bitmap Format
Document Date : 13 September 1975                      Programming Reference










                               Table of Contents

Disclaimer.................................................................  1

Foreword...................................................................  1

Licensing..................................................................  1

Format Specification.......................................................  2





















































                                                                         1


1. Disclaimer.

The information provided herein is subject to change without notice. In no
event will InfoPolska Incorporated be liable for damages, including any loss of
revenue, loss of profits or other incidental or consequential damages arising
out of the use or inability to use the information; InfoPolska Incorporated
makes no claim as to the suitability of the information.


2. Foreword.

This document defines the Tiny Bitmap Format(sm). The specification
given here defines version 0.1b.

The Tiny Bitmap Format(sm) as specified here should be considered
complete; any deviation from it should be considered invalid, including but not
limited to, the use of reserved or undefined fields within control or data
blocks, the inclusion of extraneous data within or between blocks, the use of
methods or algorithms not specifically listed as part of the format, etc. In
general, any and all deviations, extensions or modifications not specified in
this document should be considered to be in violation of the format and should
be avoided.


3. Licensing.

The Tiny Bitmap Format(c) is the copyright property of InfoPolska
Incorporated. Only InfoPolska Incorporated is authorized to define, redefine,
enhance, alter, modify or change in any way the definition of the format.

InfoPolska Incorporated hereby grants a limited, non-exclusive, royalty-free
license for the use of the Tiny Bitmap Format(sm) in computer
software; computer software utilizing TBF(sm) must acknowledge ownership of the
Tiny Bitmap Format and its Service Mark by InfoPolska Incorporated, in
User and Technical Documentation. Computer software utilizing TBF, which is
distributed or may be distributed without User or Technical Documentation must
display to the screen or printer a message acknowledging ownership of the
Tiny Bitmap Format and the Service Mark by InfoPolska Incorporated; in
this case, the acknowledgement may be displayed in an opening screen or leading
banner, or a closing screen or trailing banner. A message such as the following
may be used:

      "The Tiny Bitmap Format(c) is the Copyright property of
      InfoPolska Incorporated. TBF(sm) is a Service Mark property of
      InfoPolska Incorporated."

For further information, please contact :

      InfoPolska Incorporated
      Graphics Technology Department
      Jagiellońska 13-15
      85-067 Bydgoszcz
      Poland

	  
	  







                                                                         2



4. Format Specification.

The header of the file contains: channels, compression, width, and height. 
There is no magic in the header, the file just starts with relevant data. 
Data is not aligned to byte boundaries, which would be a waste of space.

The first bit in the file describes the number of channels in the image. The
value 0 means that the image has one channel, i.e. B/W. The value 1 means that
the image has three channels, i.e. RGB. The bit depth in each channel is always
1. Each pixel in a B/W image is one bit, and each pixel in a RGB image is 3 
bits large.

The second bit in the header is the compression flag. If the flag is 1 LZW 
compression is enabled, and if the flag is 0 there is no compression used. If 
compression is used, the pixel data is compressed. The header is always 
uncompressed.

The next 4 bits describes the bit-length of the following width and height 
fields. A value of 0 in this field means that the bit-length of width/height
is 1, a value of 1 means that the bit-length is 2 etc. This means that the
bit-length of width/length can be between 1 and 16, inclusive. The bit-length
is called BL.

The next BL bits describes the width of the image. In the same way as before,
a value of 0, means a width of 1 etc.

The next BL bits describes the height of the image, in the same manner as the 
width.

After the header follows the pixel data. The following definition assumes that 
the pixel data is already decompressed, if compression is used. Each pixel is 
described according to the number of channels. A B/W image has one bit per 
pixel, and a RGB image has 3 bits per pixel. one bit for red, one for green, 
and one for blue (in that order). The pixels are stored in rows, meaning that 
the top left pixel in the image is the first, followed by the next pixel in the
top row, etc. After the last pixel of the  first row follows the first pixel of
the second row etc. 

The bit string that constitutes the entire file is padded with zeroes to the 
next multiple of 8, and each 8-bit block is stored as a byte, using the first 
bit as the most significant bit.


Below is an example of an uncompressed 2x2 RGB image, containing a red, a 
green, a blue, and a white pixel.

      7 6 5 4 3 2 1 0        Description
     +---+-------+---+
  0  |1 0|0 0 0 1|0 1|       Header (Flags, Dimensions)
     +---+-------+---+
  1  |0 1|1 0 0 0 1 0|       Header / Image Data
     +---+-         -+
  2  |0 0 1 1 1 1 0 0|
     +---------------+
	 
The resulting image is three bytes large, and the hexadecimal representation of
the entire file is 0x8AA23C.











A. Appendix 1, Animations.

If the data block fits multiple images then the image is to be considered an
animation. Between each frame there are eight bits which describes the duration
of the last frame in milliseconds. The padding to 8-bit bytes is done only at 
the end of the file. Animation support is optional.