Image resolution is a measurement of the scanned, printed, or displayed image quality. Picture resolution on a printed photo or page is measured in dots per inch (DPI). For digital files, image resolution is expressed in pixels per inch (PPI).
The quality of pixel-based images is directly determined by resolution choices. Higher image resolution results in more detailed images but requires more storage space in a picture archiving and communication system.
The resolution for x-ray images can be defined as the period length of the finest grid that can be viewed without difficulty.

Zooming increases scale factors of images within a window. Zooming takes a selected region and extends it over the entire matrix of the displayed CT image. Usually, a zoom reconstruction increases the accuracy of the CT numbers by decreasing the overall size of the displayed image pixels, which decreases the possibility of many tissues occupying a single pixel (partial volume averaging).
Zooming or targeting is not the same as image magnification.

See also Banding.

This term usually refers to the storage of patient data and images. Images are best archived in digital form (e.g., on optical disks, DVDs, PACS systems) and not only on films (hard copies, prints). Data compression via a reduction in matrix size, pixel depth or CT numbers, will result in a loss of spatial and contrast resolution. Digital images should be converted into a universal format such as DICOM. Raw data saving is necessary when additional image reconstructions are required.

See also Picture Archiving and Communication System, and Digital Imaging and Communications in Medicine.

Despeckle is a process to remove unwanted groups of black pixels from an image.

The display matrix is the matrix in the displayed image and can be equal to or larger than the reconstruction matrix size due to interpolation procedures. This array of rows and columns of pixels is typically between 512 x 512 and 1024 x 1024.