Card image is a traditional term for a

character string In computer programming, a string is traditionally a sequence of characters, either as a literal constant or as some kind of variable. The latter may allow its elements to be mutated and the length changed, or it may be fixed (after creation). ...

, usually 80 characters in length, that was, or could be, contained on a single

punched card A punched card (also punch card or punched-card) is a stiff paper-based medium used to store digital information via the presence or absence of holes in predefined positions. Developed over the 18th to 20th centuries, punched cards were widel ...

. IBM cards were 80 characters in length. UNIVAC cards were 90 characters in length. Card image files stored on

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic ...

or disk were usually used for simulated card input or output. A punched card typically held multiple data fields, some numeric, some alphabetic. Many data formats, such as the

FITS Flexible Image Transport System (FITS) is an open standard defining a digital file format used for storage, transmission and processing of data: formatted as multi-dimensional arrays (for example a 2D image), or tables. FITS is the most commonl ...

image file An image file format is a file format for a digital image. There are many formats that can be used, such as JPEG, PNG, and GIF. Most formats up until 2022 were for storing 2D images, not 3D ones. The data stored in an image file format may be c ...

format, still use card images as basic building blocks—even though punched cards are now mostly obsolete.

References

{{compu-prog-stub Computer data storage History of software