| .TH WRJPGCOM 1 "15 June 1995" |
| .SH NAME |
| wrjpgcom \- insert text comments into a JPEG file |
| .SH SYNOPSIS |
| .B wrjpgcom |
| [ |
| .B \-replace |
| ] |
| [ |
| .BI \-comment " text" |
| ] |
| [ |
| .BI \-cfile " name" |
| ] |
| [ |
| .I filename |
| ] |
| .LP |
| .SH DESCRIPTION |
| .LP |
| .B wrjpgcom |
| reads the named JPEG/JFIF file, or the standard input if no file is named, |
| and generates a new JPEG/JFIF file on standard output. A comment block is |
| added to the file. |
| .PP |
| The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file. |
| Although the standard doesn't actually define what COM blocks are for, they |
| are widely used to hold user-supplied text strings. This lets you add |
| annotations, titles, index terms, etc to your JPEG files, and later retrieve |
| them as text. COM blocks do not interfere with the image stored in the JPEG |
| file. The maximum size of a COM block is 64K, but you can have as many of |
| them as you like in one JPEG file. |
| .PP |
| .B wrjpgcom |
| adds a COM block, containing text you provide, to a JPEG file. |
| Ordinarily, the COM block is added after any existing COM blocks; but you |
| can delete the old COM blocks if you wish. |
| .SH OPTIONS |
| Switch names may be abbreviated, and are not case sensitive. |
| .TP |
| .B \-replace |
| Delete any existing COM blocks from the file. |
| .TP |
| .BI \-comment " text" |
| Supply text for new COM block on command line. |
| .TP |
| .BI \-cfile " name" |
| Read text for new COM block from named file. |
| .PP |
| If you have only one line of comment text to add, you can provide it on the |
| command line with |
| .BR \-comment . |
| The comment text must be surrounded with quotes so that it is treated as a |
| single argument. Longer comments can be read from a text file. |
| .PP |
| If you give neither |
| .B \-comment |
| nor |
| .BR \-cfile, |
| then |
| .B wrjpgcom |
| will read the comment text from standard input. (In this case an input image |
| file name MUST be supplied, so that the source JPEG file comes from somewhere |
| else.) You can enter multiple lines, up to 64KB worth. Type an end-of-file |
| indicator (usually control-D) to terminate the comment text entry. |
| .PP |
| .B wrjpgcom |
| will not add a COM block if the provided comment string is empty. Therefore |
| \fB\-replace \-comment ""\fR can be used to delete all COM blocks from a file. |
| .SH EXAMPLES |
| .LP |
| Add a short comment to in.jpg, producing out.jpg: |
| .IP |
| .B wrjpgcom \-c |
| \fI"View of my back yard" in.jpg |
| .B > |
| .I out.jpg |
| .PP |
| Attach a long comment previously stored in comment.txt: |
| .IP |
| .B wrjpgcom |
| .I in.jpg |
| .B < |
| .I comment.txt |
| .B > |
| .I out.jpg |
| .PP |
| or equivalently |
| .IP |
| .B wrjpgcom |
| .B -cfile |
| .I comment.txt |
| .B < |
| .I in.jpg |
| .B > |
| .I out.jpg |
| .SH SEE ALSO |
| .BR cjpeg (1), |
| .BR djpeg (1), |
| .BR jpegtran (1), |
| .BR rdjpgcom (1) |
| .SH AUTHOR |
| Independent JPEG Group |
