You can upload and add images to the catalog in 2 ways
Add images as part of the product data
Upload and add as individual images.
In addition, Image manager provides advanced upload, cropping, resizing and batch operations.
Product vs individual images: we recommend using product images with product elements to keep them linked to a product instead of adding them as individual images to the catalog. This will allow you to change an image for a product in one place that will update all catalogs where it used.
Optimal image size: depends on the proportion of page the image will take. The full page is about 600px x 800px (or 800 x 600 in landscape). Therefore if your images will take not more than a quarter page (in any place you use them) than max size 400 x 300 is optimal and so on. Smaller images are better for performance, but too small size could lower quality. The only exception if you plan to use pdf format with images that require zoom (e.g. maps, charts) then you need a higher resolution (even larger than a page).
Large image collection: use Image Manager and add folders if you have a large image collection of individual images. Image manager also allows you to edit, crop, download and use advanced upload. Please note that Products folder is special and you shouldn't modify any images there as they are linked with products.
Read more about importing images from websites, Google Drive, Dropbox.
1. Add images as part of the product data
Upload and attach images to the product data from any product edit screen.
Read more about adding products to the catalog.
Now you can drag and drop images from the catalog designer Products tab and select image field you need
Use layouts to add image placeholders where you can simply drag and drop products
2. Upload and add as individual images.
Go to Image tab and drag and drop images to the designer page the same way as product elements above.
Upload new images from your computer, web or go to Image Manager for advanced upload (where you can crop, rotate and resize images).
Select image folder and filter images to find images you need.
Arrange images in the designer
You can use keyboard shortcuts for some operations: move (arrow keys), resize (Shift + arrow keys), delete (Del key).