{"history":[],"article":{"id":"8cc8ab0f-1761-4ba0-a965-30c8334ffba7","title":"DX encoding","slug":"dx-encoding","content":":::summary\n:::\n\n# \n****D****X**** (**D**igital inde**X**) encoding is a standard for marking [35 mm](https://bliptext.com/articles/135-film) and [APS](https://bliptext.com/articles/advanced-photo-system) photographic film and film cartridges, originally introduced by [Kodak](https://bliptext.com/articles/kodak) in 1983.\nIt includes multiple markings, which are a [latent image](https://bliptext.com/articles/latent-image) [barcode](https://bliptext.com/articles/barcode) on the bottom edge of the film, below the sprocket holes, a conductive pattern on the cartridge used by automatic cameras, and a [barcode](https://bliptext.com/articles/barcode) on the cartridge read by photo-finishing machines.\nThe DX encoding system was incorporated into [ANSI](https://bliptext.com/articles/american-national-standards-institute) PH1.14, which provided standards for 135 film magazines for still picture cameras and was superseded by [NAPM](https://bliptext.com/articles/i3a) IT1.14 in 1994; it is now part of [ISO](https://bliptext.com/articles/international-organization-for-standardization) standard 1007, whose latest revision was issued in 2000.\n# [135 Film Cartridge with DX barcode (top) and DX CAS code. The CAS code shows this is (top row) ISO 125 film, (bottom row) 24 exposures, +3/−1 f-stop exposure tolerance. The DX barcode reads 017563, showing DX number 109-12, 24 exposures. | upload.wikimedia.org/wikipedia/commons/3/33/Dx135can.jpg]\n\n# History\nIn order to simplify the handling of 35 mm film in 135 format cartridges, Kodak introduced the DX encoding method on 3 January 1983.\nIn contrast to the [film speed](https://bliptext.com/articles/film-speed) encoding method developed by [Fuji](https://bliptext.com/articles/fuji-company) in 1977, which used electrical contacts for [film speed](https://bliptext.com/articles/film-speed) detection on 135 format cartridges, Kodak's DX encoding system immediately met success in the marketplace.\nThe first DX encoded film to be released was the [color print film](https://bliptext.com/articles/color-print-film) [Kodacolor VR 1000](https://bliptext.com/articles/kodacolor-still-photography) in March 1983.\nThe first [point-and-shoot cameras](https://bliptext.com/articles/point-and-shoot-camera) to use DX encoding to automatically set film speed were released in 1984, including the [Pentax](https://bliptext.com/articles/pentax) Super Sport 35 / PC 35AF-M and Minolta AF-E / Freedom II.\nThe first [single-lens reflex cameras](https://bliptext.com/articles/single-lens-reflex-camera) to take advantage of DX encoding were released in 1985, including the [Konica TC-X](https://bliptext.com/articles/konica-autoreflex) SLR (1985), Pentax A3 / A3000, [Minolta 7000](https://bliptext.com/articles/minolta-7000) (February 1985) and [9000](https://bliptext.com/articles/minolta-9000) (September 1985), and the [Nikon F-301](https://bliptext.com/articles/nikon-f-301) / [N2000](https://bliptext.com/articles/nikon-n2000).\nDX-iX (data exchange - information exchange) is an expanded DX encoding system introduced in 1996 which was released as part of the [Advanced Photo System](https://bliptext.com/articles/advanced-photo-system) (APS), which use a different cartridge and film size, also known as IX240 film.\nAPS film and cameras were marketed with numerous brand names, most including an \"ix\" to emphasize the information exchange aspect, including Advantix (Kodak) and Nexia (Fujifilm).\nIn 1998, [Fujifilm](https://bliptext.com/articles/fujifilm) introduced a film identification system for [120](https://bliptext.com/articles/120-film) and [220 format](https://bliptext.com/articles/220-film) [roll film](https://bliptext.com/articles/roll-film) called Barcode System (with logo \"|||B\").\nThe [barcode](https://bliptext.com/articles/barcode) encoding the film format and length as well as the film speed and type is located on the sticker between the emulsion carrying film and the backing paper.\nThis 13-bit barcode is optically scanned by newer [medium format](https://bliptext.com/articles/medium-format) cameras like the Fujifilm GA645i Professional, GA645Wi Professional, GA645Zi Professional, GX645AF Professional, [GX680III Professional](https://bliptext.com/articles/fujifilm-gx680iii-professional), [GX680IIIS Professional](https://bliptext.com/articles/fujifilm-gx680iiis-professional), [Hasselblad H1](https://bliptext.com/articles/hasselblad-h1), [H2](https://bliptext.com/articles/hasselblad-h2), [H2](https://bliptext.com/articles/hasselblad-h2)F and [H3D](https://bliptext.com/articles/hasselblad-h3d) Model I with HM 16-32 as well as by the [Contax 645 AF](https://bliptext.com/articles/contax-645-af).\n# [Codes on Kodak ISO 400 color negative film | upload.wikimedia.org/wikipedia/commons/0/06/Kodak///400///color///film///DX///code.jpg]\n\n# Implementation\n\n## DX cartridge barcode\nNext to the film exit lip is an [Interleaved 2 of 5](https://bliptext.com/articles/interleaved-2-of-5) [barcode](https://bliptext.com/articles/barcode) and a printed number.\nThe six digits represent the I3A assigned [DX number](https://bliptext.com/articles/dx-number) (middle four digits), the number of exposures (last digit) and a proprietary manufacturer's code (first digit).\nThe DX number identifies the manufacturer, film type, and by inference, the necessary developing process type.\nThis is used by automatic photo-finishing machines to correctly process the exposed film.\n# [Agfa APX 400, cartridge number 017712 | upload.wikimedia.org/wikipedia/commons/6/6e/Agfaphoto///APX///400///%28new///emulsion%29///135///film///cartridge///04.jpg]\n\n## DX film edge barcode\nBelow the sprockets under each frame of 135 film is the DX film edge barcode.\nThe barcode is invisible until the film has been developed.\nIt is optically imprinted as a latent image during manufacturing.\nThe barcode is used by photo finishers to identify each frame for printing.\nIt consists of two parallel linear barcodes, one for a synchronizing clock called the \"clock track\", and the other encoding film data such as type, manufacturer and frame number, called the \"data track\".\nThe barcode nearest the film edge (away from the sprocket holes) contains the data track.\nThe data track sequence repeats every half frame, beginning with six start bits, followed by seven bits of DX Number Part 1, one unassigned bit, four bits of DX Number Part 2, a seven-bit frame/half-frame number, one unassigned bit, one parity bit, and finishes with four stop bits.\nThe seven-bit frame/half-frame number is called the \"DXN\" number (different than the [\"DX Number Part 1\" and \"DX Number Part 2\"](https://bliptext.com/articles/dx-number)), and is an extension on the original DX edge code, patented by Eastman Kodak in 1990.\nSome image processing software utilized by [film scanners](https://bliptext.com/articles/film-scanner) allow selection of film manufacturer and type to provide automatic color correction.\nInterpreting the DX film edge barcode may provide this information, permitting accurate color correction to be applied.\n# [DX film edge barcode; data track decodes to DX number 47-1 (Agfa Perutz Primera 200), frame 22A | upload.wikimedia.org/wikipedia/commons/7/79/Dx-film-edge-barcode.jpg]\n\n## DX Camera Auto Sensing\nThe outside of film cartridges are marked with a DX Camera Auto Sensing (CAS) code readable by many cameras.\nCameras can then automatically determine the [film speed](https://bliptext.com/articles/film-speed), number of exposures and exposure tolerance.\nWith 135 film cartridges, the DX Camera Auto Sensing code uses a 2×6 grid of rectangular contact areas on the side of the metal cartridge surface; these areas are either conductive (bare metal) or non-conductive (painted).\nThe left-most area of both rows (with the spool post on the left) are common (ground) and are thus always bare metal.\nElectrical contacts in the camera read the bit pattern.\nDiagramatically (with spool post to the left):\nIn this scheme:\nMost cameras read the film speed only, which is in the first row.\nSome cameras aimed at the consumer market only read enough bits in the first row to distinguish the most common film speeds.\nFor example, 100, 200, 400, and 800 can be distinguished by reading only S1, S2, and ground.\n# [DX CAS code positions; this film is rated at ISO 400/27°, has a 24-exposure length, and an exposure tolerance of ±1 stops.\n

1: Ground
2–6: Film speed
7: Ground
8–10: Film length
11–12: Exposure latitude

| upload.wikimedia.org/wikipedia/commons/b/b6/Codage///DX.jpg]\n\n### Film speed\nThe five bits after the ground contact in the top row can be encoded to a maximum of 32 different film speeds, but only the 24 speeds from ISO 25/15° to 5000/38°, inclusive, spaced in intervals of 1/undefined step, are used.\nThe film speed codes are in binary order if the first three bits (S1, S2, S3) are considered to identify a trio of film speeds and the last two bits (S4 and S5) are considered an adjustment of +0, +1/undefined, or +2/3 stops within that trio.\nFor example, ISO speed 25/15° is encoded as 00010, while 32/16° is 00001 and 40/17° is 00011.\nThese share a common encoding of 000xx for the first three bits, differing only in the last two bits, so 000xx designates the trio of speeds (25-32-40).\nSimilarly, the next group of three speeds are encoded 10010 (50/18°), 10001 (64/19°), and 10011 (80/20°); it is clear from examination these all (ISO 50-64-80) share the same 100xx encoding for the first three bits.\nBy comparison to the preceding set of three speeds, the encoding for 25/15° (00010) and 50/18° (10010) have the same xxx10 encoding for the last two bits; likewise, 32/16° (00001) and 64/19° (10001) share the xxx01 encoding, which indicates +1/undefined stop compared to the xxx10 encoding, and 40/17° (00011) and 80/20° (10011) share the xxx11 encoding, which indicates +2/3 stop compared to the xxx10 encoding.\n\n### Film length\nIn the second row, the first three bits represent eight possible film lengths, although in practice only 12, 20, 24 and 36 exposures are encoded.\n\n### Exposure tolerance\nThe remaining two bits of the second row give four ranges of exposure tolerance, or latitude.\nThe complete encoding scheme is illustrated in the truth table below using letters and color.","current_revision":null,"created_by":"kACnuQmH5k9Nr5VNVEpVeg7XpvUmMctD","created_at":"2025-01-25T18:31:50.062Z","updated_at":"2025-01-25T18:31:50.062Z","search_vector":"'dx':1 'encod':2","search_content":" \n \n\n# \n****D****X**** (**D**igital inde**X**) encoding is a standard for marking [35 mm](https://bliptext.com/articles/135-film) and [APS](https://bliptext.com/articles/advanced-photo-system) photographic film and film cartridges, originally introduced by [Kodak](https://bliptext.com/articles/kodak) in 1983.\nIt includes multiple markings, which are a [latent image](https://bliptext.com/articles/latent-image) [barcode](https://bliptext.com/articles/barcode) on the bottom edge of the film, below the sprocket holes, a conductive pattern on the cartridge used by automatic cameras, and a [barcode](https://bliptext.com/articles/barcode) on the cartridge read by photo-finishing machines.\nThe DX encoding system was incorporated into [ANSI](https://bliptext.com/articles/american-national-standards-institute) PH1.14, which provided standards for 135 film magazines for still picture cameras and was superseded by [NAPM](https://bliptext.com/articles/i3a) IT1.14 in 1994; it is now part of [ISO](https://bliptext.com/articles/international-organization-for-standardization) standard 1007, whose latest revision was issued in 2000.\n# [135 Film Cartridge with DX barcode (top) and DX CAS code. The CAS code shows this is (top row) ISO 125 film, (bottom row) 24 exposures, +3/−1 f-stop exposure tolerance. The DX barcode reads 017563, showing DX number 109-12, 24 exposures. | upload.wikimedia.org/wikipedia/commons/3/33/Dx135can.jpg]\n\n# History\nIn order to simplify the handling of 35 mm film in 135 format cartridges, Kodak introduced the DX encoding method on 3 January 1983.\nIn contrast to the [film speed](https://bliptext.com/articles/film-speed) encoding method developed by [Fuji](https://bliptext.com/articles/fuji-company) in 1977, which used electrical contacts for [film speed](https://bliptext.com/articles/film-speed) detection on 135 format cartridges, Kodak's DX encoding system immediately met success in the marketplace.\nThe first DX encoded film to be released was the [color print film](https://bliptext.com/articles/color-print-film) [Kodacolor VR 1000](https://bliptext.com/articles/kodacolor-still-photography) in March 1983.\nThe first [point-and-shoot cameras](https://bliptext.com/articles/point-and-shoot-camera) to use DX encoding to automatically set film speed were released in 1984, including the [Pentax](https://bliptext.com/articles/pentax) Super Sport 35 / PC 35AF-M and Minolta AF-E / Freedom II.\nThe first [single-lens reflex cameras](https://bliptext.com/articles/single-lens-reflex-camera) to take advantage of DX encoding were released in 1985, including the [Konica TC-X](https://bliptext.com/articles/konica-autoreflex) SLR (1985), Pentax A3 / A3000, [Minolta 7000](https://bliptext.com/articles/minolta-7000) (February 1985) and [9000](https://bliptext.com/articles/minolta-9000) (September 1985), and the [Nikon F-301](https://bliptext.com/articles/nikon-f-301) / [N2000](https://bliptext.com/articles/nikon-n2000).\nDX-iX (data exchange - information exchange) is an expanded DX encoding system introduced in 1996 which was released as part of the [Advanced Photo System](https://bliptext.com/articles/advanced-photo-system) (APS), which use a different cartridge and film size, also known as IX240 film.\nAPS film and cameras were marketed with numerous brand names, most including an \"ix\" to emphasize the information exchange aspect, including Advantix (Kodak) and Nexia (Fujifilm).\nIn 1998, [Fujifilm](https://bliptext.com/articles/fujifilm) introduced a film identification system for [120](https://bliptext.com/articles/120-film) and [220 format](https://bliptext.com/articles/220-film) [roll film](https://bliptext.com/articles/roll-film) called Barcode System (with logo \"|||B\").\nThe [barcode](https://bliptext.com/articles/barcode) encoding the film format and length as well as the film speed and type is located on the sticker between the emulsion carrying film and the backing paper.\nThis 13-bit barcode is optically scanned by newer [medium format](https://bliptext.com/articles/medium-format) cameras like the Fujifilm GA645i Professional, GA645Wi Professional, GA645Zi Professional, GX645AF Professional, [GX680III Professional](https://bliptext.com/articles/fujifilm-gx680iii-professional), [GX680IIIS Professional](https://bliptext.com/articles/fujifilm-gx680iiis-professional), [Hasselblad H1](https://bliptext.com/articles/hasselblad-h1), [H2](https://bliptext.com/articles/hasselblad-h2), [H2](https://bliptext.com/articles/hasselblad-h2)F and [H3D](https://bliptext.com/articles/hasselblad-h3d) Model I with HM 16-32 as well as by the [Contax 645 AF](https://bliptext.com/articles/contax-645-af).\n# [Codes on Kodak ISO 400 color negative film | upload.wikimedia.org/wikipedia/commons/0/06/Kodak///400///color///film///DX///code.jpg]\n\n# Implementation\n\n## DX cartridge barcode\nNext to the film exit lip is an [Interleaved 2 of 5](https://bliptext.com/articles/interleaved-2-of-5) [barcode](https://bliptext.com/articles/barcode) and a printed number.\nThe six digits represent the I3A assigned [DX number](https://bliptext.com/articles/dx-number) (middle four digits), the number of exposures (last digit) and a proprietary manufacturer's code (first digit).\nThe DX number identifies the manufacturer, film type, and by inference, the necessary developing process type.\nThis is used by automatic photo-finishing machines to correctly process the exposed film.\n# [Agfa APX 400, cartridge number 017712 | upload.wikimedia.org/wikipedia/commons/6/6e/Agfaphoto///APX///400///%28new///emulsion%29///135///film///cartridge///04.jpg]\n\n## DX film edge barcode\nBelow the sprockets under each frame of 135 film is the DX film edge barcode.\nThe barcode is invisible until the film has been developed.\nIt is optically imprinted as a latent image during manufacturing.\nThe barcode is used by photo finishers to identify each frame for printing.\nIt consists of two parallel linear barcodes, one for a synchronizing clock called the \"clock track\", and the other encoding film data such as type, manufacturer and frame number, called the \"data track\".\nThe barcode nearest the film edge (away from the sprocket holes) contains the data track.\nThe data track sequence repeats every half frame, beginning with six start bits, followed by seven bits of DX Number Part 1, one unassigned bit, four bits of DX Number Part 2, a seven-bit frame/half-frame number, one unassigned bit, one parity bit, and finishes with four stop bits.\nThe seven-bit frame/half-frame number is called the \"DXN\" number (different than the [\"DX Number Part 1\" and \"DX Number Part 2\"](https://bliptext.com/articles/dx-number)), and is an extension on the original DX edge code, patented by Eastman Kodak in 1990.\nSome image processing software utilized by [film scanners](https://bliptext.com/articles/film-scanner) allow selection of film manufacturer and type to provide automatic color correction.\nInterpreting the DX film edge barcode may provide this information, permitting accurate color correction to be applied.\n# [DX film edge barcode; data track decodes to DX number 47-1 (Agfa Perutz Primera 200), frame 22A | upload.wikimedia.org/wikipedia/commons/7/79/Dx-film-edge-barcode.jpg]\n\n## DX Camera Auto Sensing\nThe outside of film cartridges are marked with a DX Camera Auto Sensing (CAS) code readable by many cameras.\nCameras can then automatically determine the [film speed](https://bliptext.com/articles/film-speed), number of exposures and exposure tolerance.\nWith 135 film cartridges, the DX Camera Auto Sensing code uses a 2×6 grid of rectangular contact areas on the side of the metal cartridge surface; these areas are either conductive (bare metal) or non-conductive (painted).\nThe left-most area of both rows (with the spool post on the left) are common (ground) and are thus always bare metal.\nElectrical contacts in the camera read the bit pattern.\nDiagramatically (with spool post to the left):\nIn this scheme:\nMost cameras read the film speed only, which is in the first row.\nSome cameras aimed at the consumer market only read enough bits in the first row to distinguish the most common film speeds.\nFor example, 100, 200, 400, and 800 can be distinguished by reading only S1, S2, and ground.\n# [DX CAS code positions; this film is rated at ISO 400/27°, has a 24-exposure length, and an exposure tolerance of ±1 stops.\n \n 1: Ground \n 2–6: Film speed \n 7: Ground \n 8–10: Film length \n 11–12: Exposure latitude \n | upload.wikimedia.org/wikipedia/commons/b/b6/Codage///DX.jpg]\n\n### Film speed\nThe five bits after the ground contact in the top row can be encoded to a maximum of 32 different film speeds, but only the 24 speeds from ISO 25/15° to 5000/38°, inclusive, spaced in intervals of 1/undefined step, are used.\nThe film speed codes are in binary order if the first three bits (S1, S2, S3) are considered to identify a trio of film speeds and the last two bits (S4 and S5) are considered an adjustment of +0, +1/undefined, or +2/3 stops within that trio.\nFor example, ISO speed 25/15° is encoded as 00010, while 32/16° is 00001 and 40/17° is 00011.\nThese share a common encoding of 000xx for the first three bits, differing only in the last two bits, so 000xx designates the trio of speeds (25-32-40).\nSimilarly, the next group of three speeds are encoded 10010 (50/18°), 10001 (64/19°), and 10011 (80/20°); it is clear from examination these all (ISO 50-64-80) share the same 100xx encoding for the first three bits.\nBy comparison to the preceding set of three speeds, the encoding for 25/15° (00010) and 50/18° (10010) have the same xxx10 encoding for the last two bits; likewise, 32/16° (00001) and 64/19° (10001) share the xxx01 encoding, which indicates +1/undefined stop compared to the xxx10 encoding, and 40/17° (00011) and 80/20° (10011) share the xxx11 encoding, which indicates +2/3 stop compared to the xxx10 encoding.\n\n### Film length\nIn the second row, the first three bits represent eight possible film lengths, although in practice only 12, 20, 24 and 36 exposures are encoded.\n\n### Exposure tolerance\nThe remaining two bits of the second row give four ranges of exposure tolerance, or latitude.\nThe complete encoding scheme is illustrated in the truth table below using letters and color.","revisionCount":0},"hasMore":false,"nextCursor":null}