I will install Google's Optimus plugin, experiment with some images and find out.
https://optimus.io/en/
Just finished my experiments ...
1. Disabled the
ADS Image Optimizer.
2. Imported a new product
3. Downloaded and saved a test image from the product.
(One less than 1.00MB because of Google Optimus free version limitations)
4. Activated and optimized the image with
ADS Image Optimizer -
RESULT A
5. Deactivated the ADS Image Optimizer, Activated the Google Optimus, converted the already compressed jpg. RESULT B (No change)
6. Replaced the compressed/converted WebP image with the saved original uncompressed jpg and converted it to WebP. RESULT C (Slightly bigger than ADS compressed jpg.)
RESULT A: ADS Image Optimizer compressing jpeg image
Original size: 0.04Mb
Minized size: 0.02Mb
RESULT B: Google Optimus compressing/converting already compressed jpg to WebP
Original size: 0.04Mb
Minized size: 0.02Mb
Converted to WebP: 0.2Mb (
No change)
RESULT C: Google Optimus converting uncompressed, fresh jpg to WebP
Original size: 0.04Mb
Converted size: 0.03Mb (
A bit bigger than an ADS optimized/compressed jpg)
Conclusion
The
ADS Image Optimizer compressed jpg is actually a bit smaller than the jpg converted to WebP.
And no change when converting the already compressed image to WebP.
It seems it's only worthwhile converting jpgs to WebP if the jpgs are not being compressed by another plugin.
But it really seems like two choices ...
1. Compress jpgs with a good image optimizer plugin. (
Like the ADS Image Optimizer)
or
2. Convert jpgs to WebP.
The results are more or less the same, and it seems doing both is a waste of time.
I know this only involved 1 image, but the results are good enough for me to consider converting already compressed jpg images to WebP not really worth the effort as the compressed jpg is smaller than one converted to WebP. And at best, they'd probably be more or less the same.
So the "winner" in this test was the
ADS Image Optimizer. But I'd like to see results from any others who want to test it out ... for a bit of balance.
You can get the Google Optimus WebP converter plugin for free here ... https://optimus.io/en/ I wouldn't suggest using this instead of the ADS Image Optimizer as it does not change image titles or ALT titles. It just converts images to WebP. That's all. I just used it to see the difference between "Optimized/Compressed" images and "Converted" images.
(The free version is limited to converting images of 100 Kb / 1.00 Mb and under)