There seems to be two questions here. You can always configure options to make sure the server can resize all your images, including extremely large ones. However, it will always be slow to resize 10000x8000 images ... This would even take time on a powerful desktop. So what happens on a server, possibly with shared/limited resources, when it is asked to resize multiple extremely large images at the same time? It will be slow ...
Henri Apparently there is a problem with the generation of the thumbnails (in most cases they are not generated at all)
In your config file, increase image_resize_max_pixels. For example:
'image_resize_max_pixels' => 99000000, // number
As stated in the documentation for this option:
image_resize_max_pixels Sets the maximum allowed pixels (dimensions) when resizing images. Default value is 30000000 (30 megapixels), which allows resizing images up to approximately 6000 x 5000 px. This option is in place to protect server from attempting to resize image sizes beyond capabilities and/or to prevent slow performance.
So the reason for this, is to set a reasonable image dimensions for resizing, to protect your server from workloads that it is incapable of. It's entirely fine to increase this value, especially if you have a fast server, but then of course it will be slow when it is resizing a folder of images. Surely you understand this compromise?
As soon as the images are created and cached, it will naturally load much fast for next visitors.
Henri and calling up a folder with such images is correspondingly slow.
Do you see an image-error or the image-icon? If it didn't even try to load the thumbnails (if it showed the image-icon), it wouldn't be slow. In your case, it might still be resizing some of the images, and still be slow. If you increase image_resize_max_pixels
and it starts to process all images, it will be even slower of course.
Henri This has an extremely negative impact on the performance of the entire system.
Are there perhaps settings (e.g. maximum memory usage of php or similar) that can help here?
The above statement isn't quite logical as you seem to be asking "how can I resize extremely large images and at the same time speed up the system". Increase memory and image_resize_max_pixels
will allow you to resize extremely large images, but resizing these images be exactly as slow as your server resources. It won't go "faster" by changing memory setting etc, it will just allow your server to handle the images.
You can't expect any app to resize your 10000x8000 pixel images fast. This is a constant, regardless of what app you are running. For these kinda images, you should have a dedicated/virtual server.
I have resized images like this myself in our panorama demo. It works fine on the virtual server, although I'm sure each thumbnail took at least a couple of seconds. Not a problem of course, since they get cached.
https://demo.files.gallery/?galleries/panorama