DESCRIPTION jpegoptim is used to optimize/compress jpeg files. Program supports lossless optimization, which is based on optimizing the Huffman tables. And so called "lossy" optimization where in addition to optimizing Huffman tables user can specify upperlimit for image quality. jpegoptim syntax: jpegoptim [ options ] [ filenames ] (options at the bottom of this post) Lossless: jpegoptim file.jpg Lossy: jpegoptim --max=XX file.jpg Results of max=85 3888x2592 24bit N Exif [OK] 3435621 --> 1024056 bytes (70.19%), optimized. Results of max=65 3888x2592 24bit N Exif [OK] 3435621 --> 542022 bytes (84.22%), optimized. Original 3.4MB Optimized (jpegoptim --max=85 file.jpg) 1.0MB final filesize Optimized (jpegoptim --max=65 file.jpg) 542kB final filesize OPTIONS Options may be either the traditional POSIX one letter options, or the GNU style long options. POSIX style options start with a single ``-'', while GNU long options start with ``--''. Options offered by jpegoptim are the following: -d<path>, --dest=<path> Sets alternative destination directory where to save optimized files (default is to overwrite the originals). Please note that unchanged files won't be added to the destination directory. This means if the source file can't be compressed, no file will be created in the destination path. -f, --force Force optimization, even if the result would be larger than the original file. -h, --help Displays short usage information and exits. -m<quality>, --max=<quality> Sets the maximum image quality factor (disables lossless opti- mization mode, which is by default enabled). This option will reduce quality of those source files that were saved using higher quality setting. While files that already have lower quality setting will be compressed using the lossless optimization method. Valid values for quality parameter are: 0 - 100 -n, --noaction Don't really optimize files, just print results. -S<size>, --size=<size> Try to optimize file to given size (disables lossless opti- mizaiont mode). Target size is specified either in kilobytes (1 - n) or as percentage (1% - 99%) of the original file size. -T<treshold>, --threshold=<treshold> Keep the file unchanged if the compression gain is lower than the threshold (%). Valid values for treshold are: 0 - 100 -o, --overwrite Overwrite target file even if it exists (when using -d option). -p, --preserve Preserve file modification times. -q, --quiet Quiet mode. -t, --totals Print totals after processing all files. -v, --verbose Enables verbose mode (positively chatty). --all-normal Force all output files to be non-progressive. Can be used to con- vert all input files to progressive JPEGs when used with --force option. --all-progressive Force all output files to be progressive. Can be used to convert all input files to normal (non-progressive) JPEGs when used with --force option. --strip-all Strip all (Comment & Exif) markers from output file. (NOTE! by default only Comment & Exif markers are kept, everything else is discarded) --strip-com Strip Comment (COM) markers from output file. --strip-exif Strip EXIF markers from output file. --strip-iptc Strip IPTC markers from output file. --strip-icc Strip ICC profiles from output file.
So let's see how lossy is too lossy. Of course, these are now displaying in the forum as resized for web view although the degradation will probably become apparent once you 'click to zoom'. If we can jpegoptim all of our images from (average) 4MB down to 0.3MB or less without anyone noticing, that would be cool @ghrit --max=55 3888x2592 24bit N Exif [OK] 3435621 --> 449152 bytes (86.93%), optimized. 449kB --max=45 3888x2592 24bit N Exif [OK] 3435621 --> 394124 bytes (88.53%), optimized. 394kB --max=35 3888x2592 24bit N Exif [OK] 3435621 --> 337511 bytes (90.18%), optimized. 337kB jpegoptim --max=25 '/home/######/Desktop/IMG_3977.JPG' /home/#####/Desktop/IMG_3977.JPG 3888x2592 24bit N Exif [OK] 3435621 --> 272170 bytes (92.08%), optimized. 272kB jpegoptim --max=15 '/home/####/Desktop/IMG_3977opt15.JPG' /home/#####/Desktop/IMG_3977opt15.JPG 3888x2592 24bit N Exif [OK] 3435621 --> 196149 bytes (94.29%), optimized. 196kB jpegoptim --max=5 '/home/####/Desktop/IMG_3977.JPG' /home/#####/Desktop/IMG_3977.JPG 3888x2592 24bit N Exif [OK] 3435621 --> 111572 bytes (96.75%), optimized. 111kB Starting to pixelate to unacceptable at <25 to my eye. Last test was at 5%... Let's try max=1 for giggles jpegoptim --max=1 '/home/#####/Desktop/IMG_3977.JPG' /home/#####/Desktop/IMG_3977.JPG 3888x2592 24bit N Exif [OK] 3435621 --> 91511 bytes (97.34%), optimized. 91kB
The idea is reduced downloading time for the larger images. That seems to be a beneficial result, going by how fast those test shots loaded, but it's only one message. The proof of the method will come in pic heavy threads. Playing the obvious card, I have to wonder how important it is for high res pix within the threads, and also I have to be sympathetic to the poor souls on dialup or other restricted speed connections.
As long as the pic is not a detail issue, being shown. Many of those I will zoom in tight to see every detail. (How things work, is an interest of mine.) Casual pics, I have no problem losing a bit of clarity, but once gone, I don't think you can go backwards. Perhaps a choice could be given to posters as to which level of clarity is needed?
Still looking into this but trying to make sure that any image processing is automatic and in the background so the user is unaffected.
I think we could go lower if it benefits the site/cost/download speed. 45 or 35 possibly would still look good but would probably be the floor on what you would want to do.
