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Exeleration-G
Asked: 2016-08-31 01:50:06 +0800 CST

How can I change a picture's file size?

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Every so often, I try to upload a picture to a website and encounter a message:

Upload failed: the file size can't exceed n MB!

I know that resizing the picture's dimension should get me below n at a certain point, but the process of resizing, saving, checking file size is cumbersome. Furthermore, at times it may be handy to keep the current dimensions.

I'm looking for a way to change a picture's file size, preferably from the terminal. Is there a way to do this?

files

1 Answers

  1. Best Answer

    jpegoptim

    First install jpegoptim via 

    sudo apt install jpegoptim

    Then either try to optimize filesize of your image via

    jpegoptim /path/to/image.jpg

    or if you need a defined size via

    jpegoptim --size=512k /path/to/image.jpg

    This will overwrite the image - to make sure you have a backup while testing with jpegoptim.

    mogrify (imagemagick)

    Resizing

    You could as well use mogrify which is part of imagemagick. The following example shrinks the image dimensions to 50% (so resizing - not compressing)

    mogrify -resize 50% /path/to/image.jpg

    Compressing

    The following example shows compressing with mogrify:

    mogrify -compress JPEG -quality 50 /path/to/image.jpg

    convert (imagemagick)

    Compressing

    Compressing to 80% using convert works as follows:

    convert -quality 80% /path/to/source/image.jpg /path/to/result/image.jpg

    Convert somes with a huge set of options, so you could use

    convert -strip -interlace Plane -gaussian-blur 0.05 -quality 85% /path/to/source/image.jpg /path/to/result/image.jpg

    which should according to this post:

    • set the quality to 85
    • progressive (comprobed compression)
    • a very tiny gausssian blur to optimize the size (0.05 or 0.5 of radius) depends on the quality and size of the picture, this notably optimizes the size of the jpeg.
    • Strip any comment or exif tag

    trimage

    I am quoting the project page here

    Trimage is a cross-platform GUI and command-line interface to optimize image files for websites, using optipng, pngcrush, advpng and jpegoptim, depending on the filetype (currently, PNG and JPG files are supported).

    You can simply install it via

    sudo apt install trimage

    After starting via just the application name you might see the UI

    enter image description here

    If you need more information about trimage either visit the project page or run trimage -h to take a look on the help.

    Other tools

    There is as well optipng, pngcrush, jpegtran and several other tools in the image-size-optimization-corner .... but i've never used them.

    I'll end with some links

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