I did try that last night before posting and that does seem to be the key.
Here’s the deal:
composer media optimization image bytes optimization threshold
- 524288 (default) setting = Good quality image, 1920px.
- 200000 setting = Degraded image, since it drops resolution from 1920 to 1280.
So this morning, on my desktop, I took the same image (2392px), resized it to 1280px and it’s degraded a bit as well. So the degradation I can’t get around. It’s a product of dropping the resolution from 2392px to 1280px. It did reduce the image size by four times though.
Note: .HEIC photos don’t play by the same rules. A 4032px .HEIC was reduced to 2016px. So I don’t know how that setting was applied.
All in all, I think I get it, after a little trial and error. I think I’ll use the default settings, I really like the extra crispness of a 1920px photo over the 1280px.
Hopefully, this helps someone else out.
Edit: I dropped
composer media optimization image bytes optimization thresholdfrom the default of524288to200000. I noticed, uploading a basic .png file at 1220px @ 414kb only resulted in a file size of 406kb. By reducing the setting above to200000, the file size was reduced from 414kb to 201kb. The resolution was unchanged.So I don’t know what else is being triggered with that setting, but clearly something else to further reduce the image size.