Postcard printing generally falls into two categories: traditional offset printing and digital printing. Traditional offset printing, used in traditional printing plants, requires individual plate making. This type of printing is generally cheaper the larger the quantity, but it doesn't support small-batch printing, and even if it does, the price is very high. The second type is digital printing. Digital printing quality is no less than offset printing, and some machines even produce better results. Digital printing is characterized by its simplicity and speed, and it has very low requirements for quantity. For postcards of standard size (15x10 cm), a sheet typically contains 9 cards, and a minimum of one sheet is sufficient. In fact, as long as the format (the writing side) is consistent, different main images can be combined into one sheet. It can be said that with the increasing popularity of digital printing, it is inevitable that it will completely replace traditional printing.
Even with digital printing presses, different brands (like Xerox and HP), types (like laser and inkjet), and models (like standard definition and high definition) will produce slightly different results. It's best to choose the appropriate press platform based on the main image of the postcard you want to print.
Even with the same press and the same main image, the choice of paper will affect the final result. For example, there are different types of white cardstock (like standard domestic white cardstock), Dutch white cardstock, and various specialty papers.
Besides these factors, the most crucial element is the image resolution. If the image resolution is too low, even the best press won't help. Therefore, high image resolution is essential. If you're unsure about resolution, try this: in an image viewer, select a print size, such as 15x10 pixels, and observe the result. If it's clear, it's fine; if it's blurry, the image isn't suitable for postcards.
Of course, I'm referring to digital printing. Several stores on Taobao offer digital printing services. In addition, some merchants on Taobao use their own home printers to print. This type is not worth evaluating and does not fall into the category I mentioned above.