TRUEVISION TGA(tm) UTILITIES PACKAGE - March 26, 1990 The TGA Utilities Package contains three separate programs that can be used to manipulate image files that have been saved in the Truevsion TGA format. This format is documented in the Truevision TGA File Format Specification Version 2.0 and is available from Truevision, Inc. The three programs provided are: TGADUMP.EXE - displays on the console device a description of the various fields contained in a Truevision TGA file. TGAEDIT.EXE - provides the ability to examine and modify the contents of various control and informational fields within a TGA file. Can also be used to convert an old style TGA file into the new extended TGA file format. TGAPACK.EXE - can be used to convert an uncompressed image file into a run length compressed image file, and vice versa. Also provides an option to convert a 32 bit uncompressed image into a 24 bit uncompressed image by deleting alpha channel data. TGADUMP takes an optional filename as an argument. If the filename does not include an extension, TGADUMP will search for file with the base name specified, and one of the extensions: ".TGA", ".VST", ".ICB", ".VDA", or ".WIN". If the command is executed without an argument, the program will prompt for a filename. TGADUMP does not modify the contents of a TGA file, but provides a means to identify various characteristics of a TGA file without the necessity of a TARGA or ATVISTA videographics adapter. TGAEDIT was designed to convert an image file from the original TGA format into the extended TGA format. TGAEDIT accepts one or more filenames as arguments, and will search for default extensions in a manner similar to TGADUMP. If more than one filename is provided as arguments, TGAEDIT will process each in sequence. By default, TGAEDIT will display the contents of informational fields found in the input file, and will prompt the user for any changes desired. Simply entering RETURN or ESC at each prompt will leave the value of the field unchanged. The output file created will be in the extended TGA format, and by default, will contain a 64x64 postage stamp. Various options are available with TGAEDIT to modify this default behavior. If the -noprompt option is provided, TGAEDIT will process the file converting it to the extended format without prompting the user for field values. If the -noextend option is provided, the program will convert an extended TGA file back to an original TGA format. Various other fields of the extended TGA file are copied to the output file by default, but this behavior can be suppressed by providing one of the following options: -nocolor omits the color correction table from the output file -noscan omits the scan line table from the output file -nodev omits the developer area from the output file -nostamp omits the postage stamp from the output file Many of the control fields designating the size of the image and the pixel depth are not readily available for editing since changing these values would change the interpretation of the image data. The ability to edit these fields is provided; however, by specifying the -all option. If an option is provided that is not understood, the program displays the legal options; therefore, executing the command: TGAEDIT -help will result in a display of the recognized options. The TGAPACK program can be used to process original TGA image files. This program was written to address a potential problem with run length encoded images that were created relative to the original TGA specification. In that specification, run length packets and raw packets could contain data that actually wrapped from one edge of the image to the other. This characteristic is not allowed under the new TGA specification. Packets in a run length encoded file must end with the last pixel of a scan line. This is necessary to support features such as the scan line table. There then needs to exist a way to convert a run length encoded file saved under the less restrictive characteristics of the original TGA specification into a run length encoded image under the current TGA specification. TGAPACK can be used to accomplish this by first uncompressing the image data, and then processing the image file a second time, but requesting that the data be compressed. As with TGAEDIT, TGAPACK accepts one or more filenames as arguments, and it will search for various extensions if they are not provided with the filename. If the -unpack option is specified, TGAPACK with uncompress a compressed image file. If no option is specified, the program will convert an uncompressed image file into a compressed image file. TGAPACK also provides one other option for use with uncompressed 32 bit per pixel images. When the -32to24 option is specified, TGAPACK will process the image data stripping out the alpha data, thus converting the file to a 24 bit per pixel TGA file. As with TGAEDIT, if an unknown option is provided, a summary of the options is displayed on the console. As an example of how these utilities can be used together, suppose we had an original 32 bit compressed TGA file named IMAGE.TGA that we wanted to convert to the extended format and include a postage stamp. The following command might perform this operation satisfactorily: TGAEDIT -noprompt image If successful, the resulting file named IMAGE.TGA will be a 32 bit compressed image in the extended format, and will include a postage stamp. The original file is deleted if the conversion is successful (i.e., the output file replaces the input file). If a problem occurred during the processing (e.g., the run length encoding did not conform to the new specification), the original file is preserved and an error message is displayed. At this point, we would need to recompress the file to conform to the current specification. This is accomplished by the following commands: TGAPACK -unpack image TGAPACK image The newly compressed file can now be processed by TGAEDIT to create the proper postage stamp entry and convert the file to the extended format. If we had wanted to remove the alpha data from the image and create a 24 bit per pixel TGA file, we needed to process the file one more time using TGAPACK: TGAPACK -unpack image TGAPACK -32to24 image TGAPACK image TGAEDIT -noprompt image Of course, if we had wanted to examine the effects of these changes at any point in the process, all we needed to do is examine the file control information using TGADUMP. Two additional utilities are provided to allow the display of postage stamp data on an ATVista or on a TARGA. TSTAMP - TARGA Stamp displays postage stamp on Truevision TARGA. The program loads data directly from the file with no data padding, so that 16-bit TGA files are displayed on a Targa16, 24-bit TGA files will be displayed on a Targa24, etc. The source code is provided, and requires the TARGA Tools version 4.0 to be rebuilt. Note that the function UnPackBu will need to be changed from the 4.0 version. Refer to the comments in the TSTAMP program. VSTAMP - ATVista Stamp displays postage stamp on Truevision ATVista. This program is based on the Truevision STAGE Toolkit, and requires the STAGE driver and server files distributed with the ATVista Demo Disk version 2.0. You must have the STAGE Toolkit version 2.0 to rebuild this program. Additional files provided with this package are sample image files that have been created with various pixel depths in both uncompressed and compressed formats. Some of the file names and associated descriptions are as follows: UCM8.TGA - Uncompressed color mapped 8 bit image CCM8.TGA - Compressed color mapped 8 bit image UBW8.TGA - Uncompressed black & white 8 bit image CBW8.TGA - Compressed black & white 8 bit image UTC16.TGA - Uncompressed True Color 16 bit image CTC16.TGA - Compressed True Color 16 bit image UTC24.TGA - Uncompressed True Color 24 bit image CTC24.TGA - Compressed True Color 24 bit image UTC32.TGA - Uncompressed True Color 32 bit image CTC32.TGA - Compressed True Color 32 bit image Truevision Software Development Team