Hi, to regenerate the theme sizes for thumbnails, use this plugin:
https://ww.wp.xz.cn/plugins/regenerate-thumbnails/
If you want to edit the sizes, you need to modify functions.php on line 75-78, where it says:
// Thumbnail sizes
add_image_size( 'grayzone-small', 200, 200, true );
add_image_size( 'grayzone-medium', 520, 293, true );
add_image_size( 'grayzone-large', 780, 440, true );
And then use the regeneration plugin.
pmji, we dicussed this topic in the German support forums and I suggested, @peat1105 asks here as we didn’t find a solution.
The issue is, that e.g. when viewing a single post, the featured image looks blurry, as it gets upscaled beyond the size defined as grayzone-large(https://themes.trac.ww.wp.xz.cn/browser/grayzone/1.0.6/single.php#L32).
My suggestion was to set a fixed content width with a maximum of 780 pixel to avoid that the background image gets upscaled. However, the customizer setting Theme Options > Styling > Content max width doesn’t seem to alter the apperance of the post. The width is still responsive and goes well beyond the 780 pixel, resulting in a blurry image.
Did we miss some setting to get a better view of the featured image?
I guess the issue is that you use sidebar on home and no sidebar on single posts – which makes the site wider/blurs the featured image. What if you set website max-width to 1080px as default – it should improve the image quality. Or if that doesn’t work for some reason, put this in Customize > Additional CSS:
#wrapper-inner { max-width: 1080px; }
