some images are not served as webp with f_auto in chrome

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    Raya Straus

    Hi,

    When f_auto is used together with q_auto for JPEG images and the automatic quality algorithm decides that no chroma subsampling should be performed, the JPEG format is selected instead of WebP. This behaviour is needed because the lossy WebP format always performs chroma subsampling, which might result in a lower visual quality for some images.

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    stephane cottin

    why only in Chrome ??

    On firefox, with f_auto and q_auto, jg is rendering in WebP format

    What is the fix ?

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    Ido

    Hi Stephane

     

    The quality algorithm produces the format per specific image. So for a specific image, if it "decides" that a jpeg is preferred over webp, jpeg would be delivered for that image. This happens in Chrome and FF.

    The above links produce jpeg both on Chrome and FF as well.

     

    Could you share an example where you are seeing this differently and we could take a closer look?

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    Richard

    I actually experienced exactly the same thing with the below image:

    https://res.cloudinary.com/opt/q_auto,f_auto/palmers/menu-sprite.jpg

    The image was being served as a jpeg despite the f_auto attribute.
    So then I forced it to load as webp by removing the q_auto attribute.

    The results were:

    /q_auto,f_auto/ = 213 kb = and it was a .jpeg

    /f_auto/ = 234 kb = and loaded as a .webp (heavier weight!)


    So it turns out the Cloudinary ago is perfectly correct :) It automatically chose the smallest file size when using /q_auto,f_auto/

    Goes to show sometimes .webp isn't always smaller than .jpeg depending on the specific image. Seems like /q_auto,f_auto/ is definitely the best combinations use.

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    stephane cottin

    In this link : https://res.cloudinary.com/infostrates/image/upload/c_scale,f_auto,q_auto,w_600/v1575012952/tests/11504-SCINTILLANTES-RVB.jpg

    FF "decides" to Webp =>35 Ko
    Chrome : Jpeg => 47 Ko  instead of WebP

     

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    Aleksandar Kostadinov

    Hi Stephane,

    When I access that URL on Chrome I do get returned a WebP image that's 35KB the same as on Firefox. (Screenshot below).

    Could you clear any local browser cache or access the URL in a private/incognito window, does it still return JPEG? If so, could you please share the response to the request so that can take a look.

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    stephane cottin

    you'rr right : Chrome also returned a webp format.

    Sorry ( bad plugin to read image info )

     

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