What do you mean by height 3450px and width 1725px in calligraphy?

3450 and 1725 are all pixels. If you take a complete photo and put it in your mobile phone, you can enlarge it to (assuming your mobile phone is 1280 * 720) (3450 *1725) and divide it by (1280 * 720). That is to say, it will not be blurred if it is more than doubled. Anything larger than a pixel will feel lost and blurred.