CS/ECE 545 Utility Software

Files:

• img.c -- .img I/O utilities
• img.h -- .img definitions
• bmp.h -- .bmp definitions
• img2bmp.c -- Convert .img to .bmp
• img2tif.c -- Convert .img to .tif
• tif2img.c -- Convert .tif to .img
• prt_hdr.c -- Print .img header

These are programs or programs fragments which may be useful. Contributions in C, C++, or Java are welcome.

Standard Image Format

Here is a synopsis of the standard format for an image W pixels wide by H pixels high.

Header: 6 bytes of data. Three two-byte integers (high order byte first - "big endian" or "Motorola" encoding):

Bytes 1 -> 2: The number of Columns in the image (W). Valid values are 1 - 65535

Bytes 3 -> 4: The number of Rows in the image (H). Valid values are 1 - 65535

Bytes 5 -> 6: The number of colors. Valid values are 1 or 3.

The number of colors is 1 if the image is monochrome (gray scale) or 3 if the image is color. In that case there are three color planes stored in this order: Red (first), Green, Blue (last).

Bytes 7 -> (WxH + 6): Monochrome color data if the number of colors is 1.

 

Bytes 7-(WxH + 6): Red color data if the number of colors is 3

Bytes (WxH + 6 )-> (2xWxH + 6): Green color data

Bytes (2xWxH + 6 )-> (3xWxH + 6) Blue color data

 

The data are bytes read out in rows running from the top left. The printer's convention is used: 0x00 is white (or maximum amount of a color) and 0xFF is black.

Sample Images

Here are two images in standard image format and in TIFF format (converted using program img2tif.c described below). You will need to download the *.img files in binary format, but your browser might open the *.tif files directly.

leonardo1.img	leonardo2.img
leonardo1.tif	leonardo2.tif
leonardo1.bmp	leonardo2.bmp

Programs to read/write standard image files.

grep cc myfile.c | csh

• img.c - Image utilities. Written as carefully as MAG could, with possibly excessive error checking. This shows how to write the header in a way that works on both big-endian and small-endian computers. Note that all function calls expect the program name as the 1st argument, so that if an error occurs, the program responsible is identified. Especially useful when running batch files with many programs.
• img.h - .img definitions. Shows the basic image structure as stored in memory and the headers structure on disk.
• bmp.h - .bmp definitions. Shows the BMP image header structure.
• add_head.c - Queries operator for raw data file name containing image bytes and header numbers and writes out the image in standard format.
• prt_hdr.c - Prints out the header information for the file given on the command line. This shows how to read the header in a way that works on both big-endian and small-endian computers.
• img2bmp.c - Takes input image file name from command line and converts it to a MicroSoft BMP standard file. The resulting file is uncompressed, so expect large files, even for greyscale.
• img2tif.c - Takes input image file name from command line and converts it to a standard TIFF file. The resulting file is uncompressed (to prevent infringement of the LZW patent). This software has been carefully compared to the TIFF v6.0 Specification although a few TIFF readers (all shareware) which do not follow the Specification recommendations (on strip width) may experience difficulties.
• tif2img.c - Takes TIFF input image file name from command line and converts it to an img file. Current implementation can only create greyscale output image. Uses the TIFF library. See the man pages for libtiff on a unix system for details.
• b_di2tif.c - Same as above except it converts a batch of images. This is useful in making animations, such as the one at the top of the course home page.

Other Software