My idea is to use the uploaded thumbnail/featured image from the post as a image with the height of 750px and 100% width of the page on my page.
Everything is working fine however the image quality is very poor after I set the height to 750px.
My guess is when you upload the thumbnail somehow wordpress decompress the image to a lower quality because they expect it to be used for a small thumbnail.
Is there a way to keep the original image quality when uploaded as a featured image?
When displaying the image I'm attaching a simple class to make sure it has 750px height and 100% width:
the_post_thumbnail( array('class' => ' responsiveThumbnail'));
css:
.responsiveThumbnail {
width: 100%;
height: 750px;
margin: 0;
}