I'm looking for a WordPress image resizer, not one that resizes the image when you upload it, but one that resizes your image as soon as you access it (I'd like to keep the high-res images as high-res).
So if you uploaded a raw 5000x5000px image and it display a 100x100px image on your blog, I want it to resize the image the first time you access it and cache it as a 100x100px image instead of loading the 5000x5000px image every time.
The plugin Hammy seems to do this, but it's very outdated and no longer works.
This is exactly what Cloudinary does. Try their wordpress plugin. The free tier is sufficient for most of the small to medium scale apps.
This looks like a nice option wordpress.org/plugins/fly-dynamic-image-resizer
Here's a part from the plugin description:
How this plugin works
github: github.com/junaidbhura/fly-dynamic-image-resizer
Hope it helps :)
Guys I read all your answers but I think there is one plugin that you've missed; and I am talking about the Jetpack.
This is an amazing well made plugin made from Automattic and from the others it gives you a CDN just for images and it will resize them as well, I advice you to read their API because it gives you so many ideas ;)
Beside that since the 4.4 version you souldn't worry anymore even of the pixels dimension of your images because from now on WordPress supports the srcset attribute to serve different sizes on different devices.
Hope this gives you a little overview of Jetpack because there are plenty of useful feature inside this single plugin ;)
Jan Vladimir Mostert
Idea Incubator
The Adaptive Images plugin seems to do it for mobile. Changing the resolutions setting to:
3840, 2560, 1920, 1280, 1024, 640, 480makes it work for desktop as well.Since adding https on the blog, my PC struggled to browse the galleries due to having to decrypt all those enormous images; after installing the plugin, I can even browse it on my phone without problems.
The CPU of that instance is hard at work resizing images as you can see and the cache directory is rapidly filling up with resized images, yay!