Crop --
Mark up --
Marks sit on the whole image, so cropping, resizing and rotating keep them in place. They are baked into the saved file.
Format
Max file size
Quality becomes the ceiling: Optic lowers it until the file fits.
PNG is lossless, so there's no quality setting or size target. Make it smaller with the Size tab.
Re-encoded from pixels: EXIF, GPS and camera data are never kept. JPEG fills transparency with white.