What Is Image Resolution?
For digital images, resolution is commonly discussed as pixel dimensions, such as 1920 × 1080. Print workflows may also use a density value such as DPI or PPI.
What to do
When a website asks for an image size, it usually means pixel dimensions. When a printer asks about resolution, print dimensions and pixel density may both matter. The simplest next step is to Image Size Checker. If the issue is actually about resize image, see Resize Image as well.
Why this happens
Image problems often come from three separate variables: pixel dimensions, encoded file size and file format. Changing one does not automatically solve the others. A very large photo may need resizing even when its format is already JPG; a transparent graphic may need PNG or WebP even when the file size is acceptable; and an upload limit may be measured in megabytes rather than pixels.
Before editing, check the requirements of the place where the image will be used. That gives you a concrete target and reduces unnecessary quality loss. When possible, keep the original file and create a delivery copy for the specific destination.
Common questions
Is 1920 × 1080 a resolution?
It is a pixel dimension, and people commonly call it a resolution. More precisely, it describes the image width and height in pixels.
Does higher resolution always look better?
Only when the additional pixels are useful for the display or print size. More pixels also mean more data to store and process.
What is DPI?
DPI means dots per inch and is mainly associated with physical printing. It should not be confused with the pixel dimensions of a digital image.