Yes, this is a good tool to use if you have time...Especially when you are working with an e-commerce website, images can really slow your website load time if you so not compress them...
Hi, Dave, thanks for the comment. Yes, uncompressed images, particularly large banner heads, will certainly slow down your website.
Images, compressed and used correctly to illustrate a point, can help ranking in the search engines, but I have seen many websites, full of bells and whistles and loads of pretty pictures, not even remotely related to the subject, splashed all over the site. Then they wonder why their site takes ages to load and isn't ranking.
I have been told by PJ that jpg's are far better and use less room on your website because a jpg uses less data. png uses more data to compress the image.
Not really sure what you mean when you refer to data being used on your website to compress images. Images, using an image compression tool such as tinypng, should be compressed before placing them into your posts and pages.
I'm not quite sure on this, but If you're using a plugin such as EWWW Image Optimizer, then possibly this may be the case and your website may be using data to compress the images.
As far as image formats go, much depends on what you want to compress. GIF is best if you're using animation, it will also retain any transparency in the image.
PNG is best for line drawing, screenshots, and images that contain text. It also retains any transparency, important if you're using an image built up with layers on transparent backgrounds.
JPEG or JPG is fine for compressing standard images. If your using images with transparent backgrounds, or animation, forget it, it doesn't support either. Hope this helps. Best wishes.