Dyad Theme – Featured Images Configuration

hi

i want to change to my Dyad Theme , the default settings so the images to appears with the original rezoloution to my Home Page- Featured Posts- and to Posts .
Now the theme zoom them and they dont appear like i want.
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add_theme_support( ‘post-thumbnails’ );

/* setting custom image size for thumbnails for dyad */
add_image_size( ‘dyad-banner’, ‘1800’, ‘720’, true );
add_image_size( ‘dyad-thumbnails’, ‘630’, ‘840’, true );
add_image_size( ‘dyad-featured-image’, ‘960’, ‘1280’, true );
add_image_size( ‘dyad-featured-image-horz’, ‘960’, ‘640’, true );

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i dont know if the above has to change , and if yes, what should i do.

regards

antony