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How can I make sure that WordPress doesn't lose too much quality on uploaded images that are scaled down?

Here are some samples. You can clearly see that an image resized in Photoshop comes out with better quality than the same image resized within WordPress.

  • Original screenshot at 700px width Original screenshot at 700px width

  • Photoshop resized at 600px Photoshop resized at 600px

  • WordPress resized at 600px WordPress resized at 600px

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    You're comparing Javascript image processing to Photoshop's. That's like comparing a VW Beetle to a Ferrari. They're not even in the same league. You want better, you'll have to replace it.
    – Twifty
    Commented Sep 20, 2013 at 8:51
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    I question "clearly" seen difference in examples. It might be better to reword this in more generic way - what is quality of resize dependent on in WordPress and how to control/improve it.
    – Rarst
    Commented Sep 20, 2013 at 10:55
  • This question is lacking lots of information. PS has a variety of different save/export plugins built in (plus 3rd party ones) that have a huge amount of settings and differ in their processing and results - and are completely different from version to version. Without all the needed info it's impossible to compare anything. Showing some images doesn't help.
    – kaiser
    Commented Sep 20, 2013 at 11:01
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    The images look exactly the same, on my screen...
    – s_ha_dum
    Commented Sep 20, 2013 at 13:38

1 Answer 1

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WordPress does do some compression on images when it resizes them. You can disable this very simply using the following code (or using a plugin like this one):

function wpse_114909_image_quality() {
    return 100;
}
add_filter( 'jpeg_quality', 'wpse_114909_image_quality' );

I'm sure that GD & Imagemagick are not as good at resampling images as Photoshop is, so this may be a battle you'll never win. All the same, this will certainly help. For any images where the quality matters that much to you, you should manage the images manually instead of letting WordPress resize them.

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  • In Scott Jehls Reslonsible Responsive Design, book apart he argues that by increasing the image size two or quadruple but at the same time increasing the compression rate with broesdr again scaling down the image yields small image file size dramatically whilst keeping if not improving the visual quality. You have to see it yourself to believe it. Wbile endpoints, smartphones, got orders of .ore performance bandwith only increased linearly.
    – th00ht
    Commented Jan 18, 2023 at 18:26

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