Editing DX number (section)

===DX film canister barcode===
[[File:Kodak 400 color film DX code.jpg|right|thumb|DX CAS and barcode (315223, corresponding to DX number 95-2) on this 24-exposure roll of Kodak High Definition ISO 400 [[color print film]]]]

The DX film canister barcode is printed in [[human-readable]] text and also represented as an [[Interleaved 2 of 5]] [[barcode]], located between the electrically read silver and black [[DX Camera Auto-Sensing Code]] and the film cartridge exit lip. The size and position conform to the [[American National Standards Institute|ANSI]]/[[National Association of Photographic Manufacturers|NAPM]] IT1.14:1994 standard. Some film-processing machines optically scan the barcode when the cartridge is inserted for developing.<ref>{{cite patent |country=US |status=Patent |number=5661558A |invent1=David Lynn Patton |invent2=Lawrence Joseph Travis |invent3=Douglas Andrew McPherson |pridate=June 5, 1995 |pubdate=June 2, 1998 |assign=Eastman Kodak Co |title=Expanded film cartridge bar code}}</ref>

This film canister barcode is a six-digit number in the format ''PHHHHE'', where:
* ''P'' = proprietary prefix ranging from 0 to 9, assigned by the manufacturer
* ''HHHH'' = [[hash function|hashed]] DX number
* ''E'' = suffix identifying the number of exposures

For 135 film cartridges the DX number is [[hash function|hashed]] to produce the four-digit code ''HHHH''. To generate this code, the combination code (aka DX Number Part&nbsp;1) is multiplied by 16 and added to the specifier number (aka DX Number Part&nbsp;2). The result is prefixed with zeroes, if necessary, to make four digits. For the Agfa film assigned DX number 115-4 above, the hashed 4-digit code would be 1844:

<math>16 \times 115+4 = 1844</math>

The DX number can be recovered from the hashed code by dividing by 16, which gives the Part 1 number as the largest whole integer and the Part 2 number as the remainder:

<math>\frac{1844}{16} = 115+\frac{4}{16}</math>

The suffix digit ''E'' is a code digit for the number of full-frame exposures: 1 is for 12 exposures, 2 for 20 exposures, 3 for 24, 4 for 36, 5 for 48, 6 for 60, 0 for 72 and 7 for non-standard lengths such as 24&nbsp;+&nbsp;3.