Image Resizing - Desktop vs Mobile Differences

[Octoberon]

I’ve been taking a closer look at how Discourse deals with image uploads. I think I have a reasonable grasp of the relvevant settings now. While experimenting with a 3MB image with a resolution of 4032x3024 I noticed that uploading via a computer resulted in an image downsized to 1920x1440 but when I uploaded the same photo from the Photos app on an iPhone it was stored the image at 4032x3024.

Why is there a difference between the desktop and mobile uploads?

[Lilly]

i think this is discussed here

Srcset attribute may load larger images on mobile than desktop

I may be wrong, but I think it makes sense. If you look at the HTML srcset, the following images are served based on the device pixel ratio (x1, x1,5, x2). https://...2f50d4ad9f5f865b783b02d392de75bdceec01da_2_690x460.jpeg, https://...2f50d4ad9f5f865b783b02d392de75bdceec01da_2_1035x690.jpeg 1.5x, https://...2f50d4ad9f5f865b783b02d392de75bdceec01da_2_1380x920.jpeg 2x Usually, mobile has an x2 ratio (or more) because they have a higher pixel density. So you would want to serve images with hig…

[Falco]

@Octoberon

While experimenting with a 3MB image with a resolution of 4032x3024 I noticed that uploading via a computer resulted in an image downsized to 1920x1440 but when I uploaded the same photo from the Photos app on an iPhone it was stored the image at 4032x3024.

When Discourse detects a large enough image it triggers Client side image optimization enabled by default to optimize the image on the user device before uploading it.

This works on every device, be it mobile or desktop, except for Apple mobile devices were a series of bugs in the only browser engine allowed made we disable this feature there.

[Octoberon]

Thanks for the speedy explanations. I’d made some progress towards understanding what is going on with the client-side optimisation but the blog post has brought it together. Every day is a school day.