WP Image Compressor

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Deprecated: This is not being updated. I prefer to automate fully at the backend with this https://github.com/ployt0/wp_ss_img_resizer

Both are relatively simple projects and should provide reference materials.

I'm switching to static hosting.

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I wrote about the manual commands to do something about WordPress's wasted storage when resizing uploaded images. Typing them was time-consuming and a potential barrier to self-hosting images. While my shell's history was full of them (or more likely my PC full of terminals left open to do this day after day) I was reasonably safe from error.

I wrote that post 6 months ago and had to re-read it before going ahead with writing more posts. What better way to return to productivity than that script I'd been hankering after.

I'm also providing an accompanying "library" to interact with the API from python, wp_api, using my newly learned "application passwords".

I decided to split this code into its own repository so it can be public and have decent tests. The Vagrantfile is all you need to run them locally. Github Workflows take care of the same, on Github's cloud.

Usage

Your Linux environment must provide imagemagick. I've only tested on Ubuntu 20 and 22. I've used python 3.8 - 3.10.

One argument, the image name, is required. Your config file can be specified additionally or you can copy tests/config_template.json to the starting directory, as config.json, and adapt it. The test run by vagrant do this so I am just going to reference it:

vagrant@testrunner:/vagrant/img_compressor$ python3 compressor.py ../gallery_of_results.png -c ../tests/config.json
Please review the results at file:///home/user/PycharmProjects/wp_automations/img_compressor/gallery.html and select the set you prefer.
 0: 26KB, jpg_q50_inc_resize
 1: 30KB, jpg_q60_inc_resize
 2: 31KB, webp_q50_inc_resize
 3: 31KB, png_q16_inc_resize
 4: 32KB, png_q16_aft_resize
 5: 34KB, webp_q60_inc_resize
 6: 34KB, jpg_q70_inc_resize
 7: 34KB, png_q32_inc_resize
 8: 35KB, png_q32_aft_resize
 9: 37KB, png_q64_inc_resize
10: 38KB, webp_q70_inc_resize
11: 38KB, png_q64_aft_resize
12: 39KB, png_q128_inc_resize
13: 39KB, png_q255_inc_resize
14: 39KB, png_q255_aft_resize
15: 40KB, png_q128_aft_resize
Choose [0-15]:

Here it is recommended to open the linked gallery.html and confirm any trade offs of size for fidelity, if any, and the chosen format and q settings.

Initial gallery view

Comparative gallery view

The chosen set of images is then uploaded using the host and credentials described in whatever config.json you provided the script and deleted from the tmp subdirectory where you ran it. The only resized image not replaced is the thumbnail (150x150 or smaller) since it is generated on a different algorithm, and already needs very few KB.

Should credentials and host not be correct, the script will fail and leave the tmp directory, pictured in the gallery. This should be deleted, but any contents can be salvaged manually, beforehand.

Dev machine usage

:~/PycharmProjects/wp_img_compressor/img_compressor$ ./compressor.py some_img_path.png

The default location of the config.json is the current working directory. While you will get an error if you run it without a valid config, ie against other than the WordPress server provided in the Vagrant, you still get the gallery view. The tmp directory containing the generated images is cleaned up for you except for the folder you chose.

Out-of-sync image formats

I uploaded some images as jpeg about a year ago. Now I see their thumbnails are blank in the media library. This is because I brutishly replaced them with PNGs. The pages that use them know this and work, but WordPress is confused. I updated the SQL, the only jpegs were there in error, but nothing much changed:

mysql> update wp_posts set post_mime_type = "image/png" where post_mime_type = "image/jpeg";

I took an SQL dump and found all occurrences of the files in error, with the hyphen suffixed. These were in the wp_postmeta table. I simply pasted .png over .jpg. Done.

TODO

• unit tests for non-default size settings.
• test paths when they contain a space
• use other versions of python, down to 3.6 I think.