HDI - Apeture Cards

Aperture Cards

Microfilm' is a generic word describing several types of photographic negatives, all of which is used for storing small images of pages, drawings etc. Sometimes the negatives are mounted on cards and these are known as Aperture Cards. These, and all other types of film, can be scanned successfully.

For text and line drawings (lineart), scanning at one bit depth is required at a resolution providing 200 ppi at the final image size. Where aperture cards contain different image sizes, e.g. A4, A0 etc, and these are randomly mixed, then normally all cards would be scanned as if they are the largest drawing size i.e. A0.

Aperture Card

Aperture Cards are normally used to record images of drawings. This is a card with a 35 x 40/45mm (nominal) negative mounted on it. We can automatically batch scan Aperture Cards or manually scan individual poor quality cards if required. Images usually fall within the A0 to A4 size range.

Aperture Card with Hollerith Code

Hollerith Code Aperture Card is physically the same as above except for the punched hole code. The Hollerith code is a series of punched holes in the aperture card. The code can define the type of drawing or title and can be used for sorting cards. This type of coding is more widely used in the USA and by British companies with American parents or associates. Hdi has automatic scanners that read Hollerith code whilst scanning.