Some images shrinking when converting for epub to mobi
I created a ebook in Mac pages and converted to epub. I edited the epub in Sigil and converted to mobi using calibre. I am previewing my mobi file using Kindle Previewer. Most of my images (all jpgs < 127 KB and < 600 pixels high) look fine, except for a handful which appear to have "shrunk" to fit the page. I have specified the proper height and width in the html code for all images.
I am not sure why a few images are shrinking. How can I make sure that this does not happen? As I mentioned all images are 480 pixels wide and < 600 pixels high. All images are < 127 KB.
Any help/insights will be greatly appreciated.
Thank you in advance.