Hi, we're using a company to develop our store using the Ultimo theme (Magento 2).
I'm busy shooting, but I need to know what size and resolution I should supply the images to them for best quality. Is the resolution always 72? And what should the sizes be, in pixels?
You can check below links to default sizing for all images used in magento 2 luma theme,
Your developer team should be providing you the directions here or asking for different size of the images like Banners on home page, custom tiles etc. You may not have to provide product images in different sizes as Magento itself resize and creates different images.
On the below URL you can see the different sizes in which product images are appear in Magento. You just need to provide the optimized images in the biggest possible size of the theme so that images appear properly on the website and you do not have to compromise with the quality.
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