WordPress Images: Difference between revisions

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==History==

WordPress Thumbnails. Errr, don't you mean 'Alternate Image Sizes'? Well, yes. But WordPress life started out referring to them as 'thumbnails'. A thumbnail being a downsized (as in dimensionally and quality) to a smaller size, which in turn usually represented a link to a larger, full sized image. That's how it began with WordPress. And sort of like Max Headroom, the name just sort of stuck, even though it doesn't refer to the same thing anymore.

== Compression ==

On the subject of compression, most websites state WordPress compresses JPEG files using the setting of 90%. That is not true anymore as of early 2022. I confirmed this by experimenting with the ''add_filter( 'jpeg_quality', create_function( <nowiki>''</nowiki>, 'return 82;' ) );'' setting in the Child Theme ''functions.php'' file and it is 82%. This author confirms my testing with greater explanation: https://kinsta.com/blog/lossy-compression/ Below is the data (it was a quick test, so not too much data) and a 1066px x 799px Image with a bland background to give the compression program and easy job;

[[File:Skills JPEG 1066px x 799px.jpg|alt=Skills JPEG - 1066px x 799px|thumb|Skills JPEG - 1066px x 799px]]

Original JPEG / JPG Image File Size (100% Quality): 56.4 KB (57,795 bytes as reported by Windows)

90% Quality File Size: 47.5 KB

86% Quality File Size: 40.0 KB

85% Quality File Size: 38.1 KB

84% Quality File Size: 37.1 KB

82% Quality File Size: 34.8 KB

80% Quality File Size: 33.1 KB

</syntaxhighlight>Now here's the freaky part. What do you think the file size would be if the ''add_filter( 'jpeg_quality', create_function( <nowiki>''</nowiki>, 'return 100;' ) );'' is set to 100? 56.4 KB? Nope. Like Gomer Pyle said, "Surprise, surprise, surprise!" See the table below;<syntaxhighlight lang="text">

Original JPEG / JPG Image File Size (100% Quality): 56.4 KB (57,795 bytes as reported by Windows)

100% Quality File Size: 132 KB

WTF!?

Not until 93% Quality does the compression setting equal the original file size.

</syntaxhighlight>

[[File:Modern Art JPEG 2048px X 2048px.jpg|alt=Modern Art JPEG 2048px X 2048px|left|thumb|Modern Art JPEG 2048px X 2048px]]

But wait! That was an attention getter. What if the original file was already compressed? That would account for the odd compressing numbers, right? How about an original piece of Modern Art exported as a JPEG at 100%? Here's the data;<syntaxhighlight lang="text">

Original JPEG / JPG Image File Size (100% Quality): 479 KB

100% Quality File Size: 232 KB

82% Quality File Size: 85.8 KB

</syntaxhighlight>Phew! Sanity restored. But it is something to watch out for. If you've got a JPEG File that's already compressed, WordPress will compress it further. After about 10 uploads and downloads, it's gonna look a little fuzzy. So be careful where you get your JPEGs from. Don't just steal them. Steal them, then edit them. Just kidding. : )

Thanks to this website (http://regex.info/blog/lightroom-goodies/jpeg-quality) it is easy to discern for one's self (instead of taking my word or anyone else who writes an opinion on JPG Compression) how a gradient becomes visible to the human eye around 80% compression. They also include a bar graph that shows the file size. In the end, it seems evident the WordPress guys really did their homework and figured out that 82% is just about the perfect medium for Quality / Size. Good job guys! (I'm using the term 'guys' in a non-gender fashion)

==Image Management==

@@ Line 11: / Line 11: @@
 ==History==
 WordPress Thumbnails.  Errr, don't you mean 'Alternate Image Sizes'?  Well, yes.  But WordPress life started out referring to them as 'thumbnails'.  A thumbnail being a downsized (as in dimensionally and quality) to a smaller size, which in turn usually represented a link to a larger, full sized image.  That's how it began with WordPress.  And sort of like Max Headroom, the name just sort of stuck, even though it doesn't refer to the same thing anymore.
+== Compression ==
+On the subject of compression, most websites state WordPress compresses JPEG files using the setting of 90%.  That is not true anymore as of early 2022.  I confirmed this by experimenting with the ''add_filter( 'jpeg_quality', create_function( <nowiki>''</nowiki>, 'return 82;' ) );'' setting in the Child Theme ''functions.php'' file and it is 82%.  This author confirms my testing with greater explanation: https://kinsta.com/blog/lossy-compression/ Below is the data (it was a quick test, so not too much data) and a 1066px x 799px Image with a bland background to give the compression program and easy job;
+[[File:Skills JPEG 1066px x 799px.jpg|alt=Skills JPEG - 1066px x 799px|thumb|Skills JPEG - 1066px x 799px]]
+<br /><syntaxhighlight lang="text">
+Original JPEG / JPG Image File Size (100% Quality): 56.4 KB (57,795 bytes as reported by Windows)
+% Quality File Size: 47.5 KB
+% Quality File Size: 40.0 KB
+% Quality File Size: 38.1 KB
+% Quality File Size: 37.1 KB
+% Quality File Size: 34.8 KB
+% Quality File Size: 33.1 KB
+</syntaxhighlight>Now here's the freaky part.  What do you think the file size would be if the ''add_filter( 'jpeg_quality', create_function( <nowiki>''</nowiki>, 'return 100;' ) );'' is set to 100?  56.4 KB?  Nope.  Like Gomer Pyle said, "Surprise, surprise, surprise!"  See the table below;<syntaxhighlight lang="text">
+Original JPEG / JPG Image File Size (100% Quality): 56.4 KB (57,795 bytes as reported by Windows)
+% Quality File Size: 132 KB
+WTF!?
+Not until 93% Quality does the compression setting equal the original file size.
+</syntaxhighlight>
+[[File:Modern Art JPEG 2048px X 2048px.jpg|alt=Modern Art JPEG 2048px X 2048px|left|thumb|Modern Art JPEG 2048px X 2048px]]
+But wait!  That was an attention getter.  What if the original file was already compressed?  That would account for the odd compressing numbers, right?  How about an original piece of Modern Art exported as a JPEG at 100%?  Here's the data;<syntaxhighlight lang="text">
+Original JPEG / JPG Image File Size (100% Quality): 479 KB
+% Quality File Size: 232 KB
+% Quality File Size: 85.8 KB
+</syntaxhighlight>Phew!  Sanity restored.  But it is something to watch out for.  If you've got a JPEG File that's already compressed, WordPress will compress it further.  After about 10 uploads and downloads, it's gonna look a little fuzzy.  So be careful where you get your JPEGs from.  Don't just steal them.  Steal them, then edit them.  Just kidding.  : )
+Thanks to this website (http://regex.info/blog/lightroom-goodies/jpeg-quality) it is easy to discern for one's self (instead of taking my word or anyone else who writes an opinion on JPG Compression) how a gradient becomes visible to the human eye around 80% compression.  They also include a bar graph that shows the file size.  In the end, it seems evident the WordPress guys really did their homework and figured out that 82% is just about the perfect medium for Quality / Size.  Good job guys! (I'm using the term 'guys' in a non-gender fashion)
 ==Image Management==