Why does google speed change photo resolution instead of compression (wordpress site)?

Question

Google

Hello. I check the site in google speed, the result is in the yellow zone, below it is proposed to download compressed photos. I download, and there they are of reduced resolution (initially, the photo is 560x385 and weighs ~ 50kb, in the proposed archive from google speed the same photo weighs ~ 10kb, but the resolution is reduced to ~ 230width). I used these photos from google speed, the site was in the green zone, but on small screens these images (post images) look smudged because 230px is used instead of 560px. Why doesn't google speed compress photos, but change the resolution?

Answer 1

Hello.
Usually Google complains about images for 2 reasons:
- Serve scaled image sizes (requests to use the maximum approximate image sizes, instead of specifying them with CSS). For example, if a picture is 1600x1200 pixels in size, and the site displays 640x480 in size, then it is clear that Google will complain. You need to specify the exact dimensions. On VP, I usually solve a similar question with the help of thumbnails. For example, I do not display images in archives in full size with a CSS limit, but in a specific size using add_image_size
https://developer.wordpress.org/reference/function...
- Optimize images (asks to compress)
As for optimization... Then you can use plugins Wp Smush, EVWW, TinyPNG
And you can download all the content (uploads) and compress all the pictures at once with the program
https://nikkhokkho.sourceforge.io/static.php?page=...
And it changes the size of the pictures, apparently, because of the scaled images. I also recommend checking pagespeed using GTmetrix.
I wrote more about optimization here - Why does Google swear at itself in Google PageSpeed ​​Insights about fonts?