The resolution of an image is measured in pixels per inch (PPI) or dots per inch (DPI), and it describes the density of pixels or dots that make up the image.

You might have heard that 72 PPI is an ideal web image resolution. However, high-resolution displays might require higher resolution. The best resolution can vary, and it depends on several factors:

• Size of the image
• Display size and resolution of the device
• Intended use of the image

While the file format can affect the quality and compression of the image, it doesn't directly influence the resolution of the image. The resolution is a measure of the number of pixels in an image, not the way those pixels are stored or compressed.

In general, it's vital to strike a balance between image quality and file size when choosing a resolution. Higher-resolution images have better quality but larger file sizes, while lower-resolution images have smaller file sizes but may reduce quality.