How to display the product pictures of the department store website

How to display the product picture of the mall type website
Backstage only upload a picture of the most elephant products.
If the front desk shows this big one, the website is too big.
What are the pictures of the mall-like websites now showing?
(The front desk can see small, medium, large size pictures)
Did you change the image of the most elephant from PHP to show it?

Or is there another way?
Thank you
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Generate thumbnail images ....
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Generate different proportions of the picture, need to what proportion, as long as the set scale can be found in a PHP thumbnail class

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Mall or similar CMS generally have templates, upload pictures, according to the size of the template to generate multiple thumbnails saved in the server
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thinkphp frame Next full version, thinkphp\library\think\image\driver\gd.class.php look at this kind of thumb method
There are 2 thumbnail generation strategies, which are generated synchronously on upload and generated when the page is called.

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