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Hi,

Just got the results from WebPageTest for my website. Got all As except Compress Images. A list of about 100 images with either Warning or Failed designation.
But I checked the images with Failed grade : they are jpeg files that have been optimized for web using Photoshop and around 200 KB in size.
What caused the Fail grade?
Do you have a link to the actual test? My guess is that they were (possibly) saved "for web" in photoshop but with a quality level that was too high.

If you click on the waterfall on the main page to go to the full waterfall page and then scrool below the waterfall there will be a "view all images" link that brings up a view that displays all of the images and the savings for each. If you find one in particular you want more details on there will be an "Analyze JPEG" link that will give you an idea of where the extra image bytes are coming from.
http://www.webpagetest.org/result/160728_PC_34BN/

Hi pmeenan,
Thanks for the quick reply. I am new to all this.
So, if I take the first image on the list, it gives three versions of the image :
Image, Optimized Image and Quality 85 Image.
Is it the Quality 85 that I should be using?
If so, should I lower the file size manually by Photoshop?
Looking at the actual images, you also have some other issues going on.

This image for example: http://96b1ada84e3baac616429bf8.lejgz897...jpg?deb23c

Is 46x46px in the UI but is a 1134x1134px image. You should resize the images like that to the size you actually need. And for 2-color images (and other non-photo images) png will usually be a better choice than JPEG.

For the other photos, yes, you should reduce the quality level when saving from Photoshop. Quality level 60 in Photoshop's "Save for web" is usually safe but you can tweak the settings until it is as small as possible but still looks visually good.
Thanks so much pmeenan, for all the help.
You can try also tools like JPEGmini
http://www.jpegmini.com/

and Imageoptim
https://imageoptim.com/

to compress even better images

I personnaly process all my JPEG with Jpegmini and all PNG with Imageoptim (and ImageAlpha to reduce colors)
Reference URL's