
Hi,
There is no method currently available by which you can compress your images using the image() function but here's what you can do.
Instead of embedding images directly into the Excel file using image(), you can use hyperlinks to display images from external URLs. This won't increase the file size significantly, but it will need your internet connection to load the images.
Or you'll just have to compress your images before-hand and keep them with you. You can use online tools for compressing images in bulk.
Best Regards.