Creating an image gallery. Using WP for image upload & management. Pictures will be uploaded of various file sizes and pixel dimensions. Page load time and SEO are negatively affected by loading large files.
Question: When does WP resize uploaded images? Is it only on display / output?
If so, that means the browser needs to fetch the original, large, slow image and then condense it before serving it to the viewer. Obviously this is bad.
If the above is true, is there a way (without a plugin) to resize an image on upload to a standardized size (say 320x240). Trying to avoid 3rd party (Photoshop, etc) software.