Hi,
I can understand your reasoning that you would prefer that only the original image would be compressed, and let WordPress do the resizing.
There is however a difference between resizing a compressed image and compressing a resized image. Both will not end up the same. We compress the image after WordPress has resized the original uncompressed image.
This should generally give better results than when WordPress would merely resize the compressed original. You might not notice much difference for small sizes, but for the bigger sizes you can surely notice a difference in image size.
From a cost saving perspective resizing the compressed original indeed would be best, but from an image size saving perspective we think our way of doing it gives better results.
I hope that explains sufficiently why we do want to compress the resized versions as well.
I installed this on a friend’s real estate (rentals) site. I’ve cut back on the image sizes to be compressed and that has helped. His site has about 10 different image sizes, some of which are never used.
Some thoughts:
1) Don’t compress the smallest sizes. TinyJPG doesn’t distinguish between large and small images when counting compressions. The smallest images aren’t going to benefit as much as the larger images when it comes to overall savings.
2) I really like the option to Resize and Compress the original image. The site I manage uses Original image when you click on the thumbs. Scaling down a 6 Megapixel image down to 1280 max really helped.
3) When I go over the 500 free images, an additional thousand compressions only cost me $20 or so, which I find worth paying for the service.
