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| 1 .TH WRJPGCOM 1 "15 June 1995" |
| 2 .SH NAME |
| 3 wrjpgcom \- insert text comments into a JPEG file |
| 4 .SH SYNOPSIS |
| 5 .B wrjpgcom |
| 6 [ |
| 7 .B \-replace |
| 8 ] |
| 9 [ |
| 10 .BI \-comment " text" |
| 11 ] |
| 12 [ |
| 13 .BI \-cfile " name" |
| 14 ] |
| 15 [ |
| 16 .I filename |
| 17 ] |
| 18 .LP |
| 19 .SH DESCRIPTION |
| 20 .LP |
| 21 .B wrjpgcom |
| 22 reads the named JPEG/JFIF file, or the standard input if no file is named, |
| 23 and generates a new JPEG/JFIF file on standard output. A comment block is |
| 24 added to the file. |
| 25 .PP |
| 26 The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file. |
| 27 Although the standard doesn't actually define what COM blocks are for, they |
| 28 are widely used to hold user-supplied text strings. This lets you add |
| 29 annotations, titles, index terms, etc to your JPEG files, and later retrieve |
| 30 them as text. COM blocks do not interfere with the image stored in the JPEG |
| 31 file. The maximum size of a COM block is 64K, but you can have as many of |
| 32 them as you like in one JPEG file. |
| 33 .PP |
| 34 .B wrjpgcom |
| 35 adds a COM block, containing text you provide, to a JPEG file. |
| 36 Ordinarily, the COM block is added after any existing COM blocks; but you |
| 37 can delete the old COM blocks if you wish. |
| 38 .SH OPTIONS |
| 39 Switch names may be abbreviated, and are not case sensitive. |
| 40 .TP |
| 41 .B \-replace |
| 42 Delete any existing COM blocks from the file. |
| 43 .TP |
| 44 .BI \-comment " text" |
| 45 Supply text for new COM block on command line. |
| 46 .TP |
| 47 .BI \-cfile " name" |
| 48 Read text for new COM block from named file. |
| 49 .PP |
| 50 If you have only one line of comment text to add, you can provide it on the |
| 51 command line with |
| 52 .BR \-comment . |
| 53 The comment text must be surrounded with quotes so that it is treated as a |
| 54 single argument. Longer comments can be read from a text file. |
| 55 .PP |
| 56 If you give neither |
| 57 .B \-comment |
| 58 nor |
| 59 .BR \-cfile , |
| 60 then |
| 61 .B wrjpgcom |
| 62 will read the comment text from standard input. (In this case an input image |
| 63 file name MUST be supplied, so that the source JPEG file comes from somewhere |
| 64 else.) You can enter multiple lines, up to 64KB worth. Type an end-of-file |
| 65 indicator (usually control-D) to terminate the comment text entry. |
| 66 .PP |
| 67 .B wrjpgcom |
| 68 will not add a COM block if the provided comment string is empty. Therefore |
| 69 \fB\-replace \-comment ""\fR can be used to delete all COM blocks from a file. |
| 70 .SH EXAMPLES |
| 71 .LP |
| 72 Add a short comment to in.jpg, producing out.jpg: |
| 73 .IP |
| 74 .B wrjpgcom \-c |
| 75 \fI"View of my back yard" in.jpg |
| 76 .B > |
| 77 .I out.jpg |
| 78 .PP |
| 79 Attach a long comment previously stored in comment.txt: |
| 80 .IP |
| 81 .B wrjpgcom |
| 82 .I in.jpg |
| 83 .B < |
| 84 .I comment.txt |
| 85 .B > |
| 86 .I out.jpg |
| 87 .PP |
| 88 or equivalently |
| 89 .IP |
| 90 .B wrjpgcom |
| 91 .B -cfile |
| 92 .I comment.txt |
| 93 .B < |
| 94 .I in.jpg |
| 95 .B > |
| 96 .I out.jpg |
| 97 .SH SEE ALSO |
| 98 .BR cjpeg (1), |
| 99 .BR djpeg (1), |
| 100 .BR jpegtran (1), |
| 101 .BR rdjpgcom (1) |
| 102 .SH AUTHOR |
| 103 Independent JPEG Group |
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Chromium Code Reviews
Issue 1953443002:
Update to libjpeg_turbo 1.4.90 (Closed)
Base URL: https://chromium.googlesource.com/chromium/deps/libjpeg_turbo.git@master