The resolution is indicated with the DPI (dots per inch) value. This DPI value indicates how many pixels per inch (one inch corresponds to approx. 2.5 cm) are displayed. If you want to achieve a high-quality, fine-grained image, you need a high DPI value. For professional printing, for example, the DPI value should be 300.
Caution: If an image is saved in a very high resolution and implemented in web pages, for example, this will increase the upload time and thus have a negative impact on the organic ranking in Google results. For viewing an image on a screen, the resolution in DPI is irrelevant, as the display on a monitor is always in pixels.