Package com.drew.metadata.exif.makernotes

Class NikonType2MakernoteDirectory

java.lang.Object
com.drew.metadata.Directory
com.drew.metadata.exif.makernotes.NikonType2MakernoteDirectory
public class NikonType2MakernoteDirectory extends Directory
Describes tags specific to Nikon (type 2) cameras. Type-2 applies to the E990 and D-series cameras such as the E990, D1, D70 and D100.

Thanks to Fabrizio Giudici for publishing his reverse-engineering of the D100 makernote data. http://www.timelesswanderings.net/equipment/D100/NEF.html

Note that the camera implements image protection (locking images) via the file's 'readonly' attribute. Similarly image hiding uses the 'hidden' attribute (observed on the D70). Consequently, these values are not available here.

Additional sample images have been observed, and their tag values recorded in javadoc comments for each tag's field. New tags have subsequently been added since Fabrizio's observations.

In earlier models (such as the E990 and D1), this directory begins at the first byte of the makernote IFD. In later models, the IFD was given the standard prefix to indicate the camera models (most other manufacturers also provide this prefix to aid in software decoding).

Author:
Drew Noakes https://drewnoakes.com

  • Field Details

    • TAG_FIRMWARE_VERSION

      public static final int TAG_FIRMWARE_VERSION
      Values observed - 0200 (D70) - 0200 (D1X)
      See Also:

    • TAG_ISO_1

      public static final int TAG_ISO_1
      Values observed - 0 250 - 0 400
      See Also:

    • TAG_COLOR_MODE

      public static final int TAG_COLOR_MODE
      The camera's color mode, as an uppercase string. Examples include:
      • B & W
      • COLOR
      • COOL
      • SEPIA
      • VIVID
      See Also:

    • TAG_QUALITY_AND_FILE_FORMAT

      public static final int TAG_QUALITY_AND_FILE_FORMAT
      The camera's quality setting, as an uppercase string. Examples include:
      • BASIC
      • FINE
      • NORMAL
      • RAW
      • RAW2.7M
      See Also:

    • TAG_CAMERA_WHITE_BALANCE

      public static final int TAG_CAMERA_WHITE_BALANCE
      The camera's white balance setting, as an uppercase string. Examples include:
      • AUTO
      • CLOUDY
      • FLASH
      • FLUORESCENT
      • INCANDESCENT
      • PRESET
      • PRESET0
      • PRESET1
      • PRESET3
      • SUNNY
      • WHITE PRESET
      • 4350K
      • 5000K
      • DAY WHITE FL
      • SHADE
      See Also:

    • TAG_CAMERA_SHARPENING

      public static final int TAG_CAMERA_SHARPENING
      The camera's sharpening setting, as an uppercase string. Examples include:
      • AUTO
      • HIGH
      • LOW
      • NONE
      • NORMAL
      • MED.H
      • MED.L
      See Also:

    • TAG_AF_TYPE

      public static final int TAG_AF_TYPE
      The camera's auto-focus mode, as an uppercase string. Examples include:
      • AF-C
      • AF-S
      • MANUAL
      • AF-A
      See Also:

    • TAG_FLASH_SYNC_MODE

      public static final int TAG_FLASH_SYNC_MODE
      The camera's flash setting, as an uppercase string. Examples include:
      • NORMAL
      • RED-EYE
      • SLOW
      • NEW_TTL
      • REAR
      • REAR SLOW
      Note: when TAG_AUTO_FLASH_MODE is blank (whitespace), Nikon Browser displays "Flash Sync Mode: Not Attached"
      See Also:

    • TAG_AUTO_FLASH_MODE

      public static final int TAG_AUTO_FLASH_MODE
      The type of flash used in the photograph, as a string. Examples include:
      • Built-in,TTL
      • NEW_TTL Nikon Browser interprets as "D-TTL"
      • Built-in,M
      • Optional,TTL with speedlight SB800, flash sync mode as "NORMAL"
      See Also:

    • TAG_UNKNOWN_34

      public static final int TAG_UNKNOWN_34
      An unknown tag, as a rational. Several values given here: http://gvsoft.homedns.org/exif/makernote-nikon-type2.html#0x000b
      See Also:

    • TAG_CAMERA_WHITE_BALANCE_FINE

      public static final int TAG_CAMERA_WHITE_BALANCE_FINE
      The camera's white balance bias setting, as an uint16 array having either one or two elements.
      • 0
      • 1
      • -3
      • -2
      • -1
      • 0,0
      • 1,0
      • 5,-5
      See Also:

    • TAG_CAMERA_WHITE_BALANCE_RB_COEFF

      public static final int TAG_CAMERA_WHITE_BALANCE_RB_COEFF
      The first two numbers are coefficients to multiply red and blue channels according to white balance as set in the camera. The meaning of the third and the fourth numbers is unknown. Values observed - 2.25882352 1.76078431 0.0 0.0 - 10242/1 34305/1 0/1 0/1 - 234765625/100000000 1140625/1000000 1/1 1/1
      See Also:

    • TAG_PROGRAM_SHIFT

      public static final int TAG_PROGRAM_SHIFT
      The camera's program shift setting, as an array of four integers. The value, in EV, is calculated as a*b/c.
      • 0,1,3,0 = 0 EV
      • 1,1,3,0 = 0.33 EV
      • -3,1,3,0 = -1 EV
      • 1,1,2,0 = 0.5 EV
      • 2,1,6,0 = 0.33 EV
      See Also:

    • TAG_EXPOSURE_DIFFERENCE

      public static final int TAG_EXPOSURE_DIFFERENCE
      The exposure difference, as an array of four integers. The value, in EV, is calculated as a*b/c.
      • -105,1,12,0 = -8.75 EV
      • -72,1,12,0 = -6.00 EV
      • -11,1,12,0 = -0.92 EV
      See Also:

    • TAG_ISO_MODE

      public static final int TAG_ISO_MODE
      The camera's ISO mode, as an uppercase string.
      • AUTO
      • MANUAL
      See Also:

    • TAG_DATA_DUMP

      public static final int TAG_DATA_DUMP
      Added during merge of Type2 & Type3. May apply to earlier models, such as E990 and D1.
      See Also:

    • TAG_PREVIEW_IFD

      public static final int TAG_PREVIEW_IFD
      Preview to another IFD (?)

      Details here: http://gvsoft.homedns.org/exif/makernote-nikon-2-tag0x0011.html // TODO if this is another IFD, decode it

      See Also:

    • TAG_AUTO_FLASH_COMPENSATION

      public static final int TAG_AUTO_FLASH_COMPENSATION
      The flash compensation, as an array of four integers. The value, in EV, is calculated as a*b/c.
      • -18,1,6,0 = -3 EV
      • 4,1,6,0 = 0.67 EV
      • 6,1,6,0 = 1 EV
      See Also:

    • TAG_ISO_REQUESTED

      public static final int TAG_ISO_REQUESTED
      The requested ISO value, as an array of two integers.
      • 0,0
      • 0,125
      • 1,2500
      See Also:

    • TAG_IMAGE_BOUNDARY

      public static final int TAG_IMAGE_BOUNDARY
      Defines the photo corner coordinates, in 8 bytes. Treated as four 16-bit integers, they decode as: top-left (x,y); bot-right (x,y) - 0 0 49163 53255 - 0 0 3008 2000 (the image dimensions were 3008x2000) (D70)
      • 0,0,4288,2848 The max resolution of the D300 camera
      • 0,0,3008,2000 The max resolution of the D70 camera
      • 0,0,4256,2832 The max resolution of the D3 camera
      See Also:

    • TAG_FLASH_EXPOSURE_COMPENSATION

      public static final int TAG_FLASH_EXPOSURE_COMPENSATION
      The flash exposure compensation, as an array of four integers. The value, in EV, is calculated as a*b/c.
      • 0,0,0,0 = 0 EV
      • 0,1,6,0 = 0 EV
      • 4,1,6,0 = 0.67 EV
      See Also:

    • TAG_FLASH_BRACKET_COMPENSATION

      public static final int TAG_FLASH_BRACKET_COMPENSATION
      The flash bracket compensation, as an array of four integers. The value, in EV, is calculated as a*b/c.
      • 0,0,0,0 = 0 EV
      • 0,1,6,0 = 0 EV
      • 4,1,6,0 = 0.67 EV
      See Also:

    • TAG_AE_BRACKET_COMPENSATION

      public static final int TAG_AE_BRACKET_COMPENSATION
      The AE bracket compensation, as a rational number.
      • 0/0
      • 0/1
      • 0/6
      • 4/6
      • 6/6
      See Also:

    • TAG_FLASH_MODE

      public static final int TAG_FLASH_MODE
      Flash mode, as a string.
      • Red Eye Reduction
      • D-Lighting
      • Distortion control
      See Also:

    • TAG_CROP_HIGH_SPEED

      public static final int TAG_CROP_HIGH_SPEED
      See Also:

    • TAG_EXPOSURE_TUNING

      public static final int TAG_EXPOSURE_TUNING
      See Also:

    • TAG_CAMERA_SERIAL_NUMBER

      public static final int TAG_CAMERA_SERIAL_NUMBER
      The camera's serial number, as a string. Note that D200 is always blank, and D50 is always "D50".
      See Also:

    • TAG_COLOR_SPACE

      public static final int TAG_COLOR_SPACE
      The camera's color space setting.
      • 1 sRGB
      • 2 Adobe RGB
      See Also:

    • TAG_VR_INFO

      public static final int TAG_VR_INFO
      See Also:

    • TAG_IMAGE_AUTHENTICATION

      public static final int TAG_IMAGE_AUTHENTICATION
      See Also:

    • TAG_FACE_DETECT

      public static final int TAG_FACE_DETECT
      See Also:

    • TAG_ACTIVE_D_LIGHTING

      public static final int TAG_ACTIVE_D_LIGHTING
      The active D-Lighting setting.
      • 0 Off
      • 1 Low
      • 3 Normal
      • 5 High
      • 7 Extra High
      • 65535 Auto
      See Also:

    • TAG_PICTURE_CONTROL

      public static final int TAG_PICTURE_CONTROL
      See Also:

    • TAG_WORLD_TIME

      public static final int TAG_WORLD_TIME
      See Also:

    • TAG_ISO_INFO

      public static final int TAG_ISO_INFO
      See Also:

    • TAG_UNKNOWN_36

      public static final int TAG_UNKNOWN_36
      See Also:

    • TAG_UNKNOWN_37

      public static final int TAG_UNKNOWN_37
      See Also:

    • TAG_UNKNOWN_38

      public static final int TAG_UNKNOWN_38
      See Also:

    • TAG_UNKNOWN_39

      public static final int TAG_UNKNOWN_39
      See Also:

    • TAG_VIGNETTE_CONTROL

      public static final int TAG_VIGNETTE_CONTROL
      The camera's vignette control setting.
      • 0 Off
      • 1 Low
      • 3 Normal
      • 5 High
      See Also:

    • TAG_DISTORT_INFO

      public static final int TAG_DISTORT_INFO
      See Also:

    • TAG_UNKNOWN_41

      public static final int TAG_UNKNOWN_41
      See Also:

    • TAG_UNKNOWN_42

      public static final int TAG_UNKNOWN_42
      See Also:

    • TAG_UNKNOWN_43

      public static final int TAG_UNKNOWN_43
      See Also:

    • TAG_UNKNOWN_44

      public static final int TAG_UNKNOWN_44
      See Also:

    • TAG_UNKNOWN_45

      public static final int TAG_UNKNOWN_45
      See Also:

    • TAG_UNKNOWN_46

      public static final int TAG_UNKNOWN_46
      See Also:

    • TAG_IMAGE_ADJUSTMENT

      public static final int TAG_IMAGE_ADJUSTMENT
      The camera's image adjustment setting, as a string.
      • AUTO
      • CONTRAST(+)
      • CONTRAST(-)
      • NORMAL
      • B & W
      • BRIGHTNESS(+)
      • BRIGHTNESS(-)
      • SEPIA
      See Also:

    • TAG_CAMERA_TONE_COMPENSATION

      public static final int TAG_CAMERA_TONE_COMPENSATION
      The camera's tone compensation setting, as a string.
      • NORMAL
      • LOW
      • MED.L
      • MED.H
      • HIGH
      • AUTO
      See Also:

    • TAG_ADAPTER

      public static final int TAG_ADAPTER
      A description of any auxiliary lens, as a string.
      • OFF
      • FISHEYE 1
      • FISHEYE 2
      • TELEPHOTO 2
      • WIDE ADAPTER
      See Also:

    • TAG_LENS_TYPE

      public static final int TAG_LENS_TYPE
      The type of lens used, as a byte.
      • 0x00 AF
      • 0x01 MF
      • 0x02 D
      • 0x06 G, D
      • 0x08 VR
      • 0x0a VR, D
      • 0x0e VR, G, D
      See Also:

    • TAG_LENS

      public static final int TAG_LENS
      A pair of focal/max-fstop values that describe the lens used. Values observed - 180.0,180.0,2.8,2.8 (D100) - 240/10 850/10 35/10 45/10 - 18-70mm f/3.5-4.5 (D70) - 17-35mm f/2.8-2.8 (D1X) - 70-200mm f/2.8-2.8 (D70) Nikon Browser identifies the lens as "18-70mm F/3.5-4.5 G" which is identical to metadata extractor, except for the "G". This must be coming from another tag...
      See Also:

    • TAG_MANUAL_FOCUS_DISTANCE

      public static final int TAG_MANUAL_FOCUS_DISTANCE
      Added during merge of Type2 & Type3. May apply to earlier models, such as E990 and D1.
      See Also:

    • TAG_DIGITAL_ZOOM

      public static final int TAG_DIGITAL_ZOOM
      The amount of digital zoom used.
      See Also:

    • TAG_FLASH_USED

      public static final int TAG_FLASH_USED
      Whether the flash was used in this image.
      • 0 Flash Not Used
      • 1 Manual Flash
      • 3 Flash Not Ready
      • 7 External Flash
      • 8 Fired, Commander Mode
      • 9 Fired, TTL Mode
      See Also:

    • TAG_AF_FOCUS_POSITION

      public static final int TAG_AF_FOCUS_POSITION
      The position of the autofocus target.
      See Also:

    • TAG_SHOOTING_MODE

      public static final int TAG_SHOOTING_MODE
      The camera's shooting mode.

      A bit-array with:

      • 0 Single Frame
      • 1 Continuous
      • 2 Delay
      • 8 PC Control
      • 16 Exposure Bracketing
      • 32 Auto ISO
      • 64 White-Balance Bracketing
      • 128 IR Control
      See Also:

    • TAG_UNKNOWN_20

      public static final int TAG_UNKNOWN_20
      See Also:

    • TAG_LENS_STOPS

      public static final int TAG_LENS_STOPS
      Lens stops, as an array of four integers. The value, in EV, is calculated as a*b/c.
      • 64,1,12,0 = 5.33 EV
      • 72,1,12,0 = 6 EV
      See Also:

    • TAG_CONTRAST_CURVE

      public static final int TAG_CONTRAST_CURVE
      See Also:

    • TAG_CAMERA_COLOR_MODE

      public static final int TAG_CAMERA_COLOR_MODE
      The color space as set in the camera, as a string.
      • MODE1 = Mode 1 (sRGB)
      • MODE1a = Mode 1 (sRGB)
      • MODE2 = Mode 2 (Adobe RGB)
      • MODE3 = Mode 2 (sRGB): Higher Saturation
      • MODE3a = Mode 2 (sRGB): Higher Saturation
      • B & W = B & W
      See Also:

    • TAG_UNKNOWN_47

      public static final int TAG_UNKNOWN_47
      See Also:

    • TAG_SCENE_MODE

      public static final int TAG_SCENE_MODE
      The camera's scene mode, as a string. Examples include:
      • BEACH/SNOW
      • CLOSE UP
      • NIGHT PORTRAIT
      • PORTRAIT
      • ANTI-SHAKE
      • BACK LIGHT
      • BEST FACE
      • BEST
      • COPY
      • DAWN/DUSK
      • FACE-PRIORITY
      • FIREWORKS
      • FOOD
      • HIGH SENS.
      • LAND SCAPE
      • MUSEUM
      • PANORAMA ASSIST
      • PARTY/INDOOR
      • SCENE AUTO
      • SMILE
      • SPORT
      • SPORT CONT.
      • SUNSET
      See Also:

    • TAG_LIGHT_SOURCE

      public static final int TAG_LIGHT_SOURCE
      The lighting type, as a string. Examples include:
      • NATURAL
      • SPEEDLIGHT
      • COLORED
      • MIXED
      • NORMAL
      See Also:

    • TAG_SHOT_INFO

      public static final int TAG_SHOT_INFO
      Advertised as ASCII, but actually isn't. A variable number of bytes (eg. 18 to 533). Actual number of bytes appears fixed for a given camera model.
      See Also:

    • TAG_CAMERA_HUE_ADJUSTMENT

      public static final int TAG_CAMERA_HUE_ADJUSTMENT
      The hue adjustment as set in the camera. Values observed are either 0 or 3.
      See Also:

    • TAG_NEF_COMPRESSION

      public static final int TAG_NEF_COMPRESSION
      The NEF (RAW) compression. Examples include:
      • 1 Lossy (Type 1)
      • 2 Uncompressed
      • 3 Lossless
      • 4 Lossy (Type 2)
      See Also:

    • TAG_SATURATION

      public static final int TAG_SATURATION
      The saturation level, as a signed integer. Examples include:
      • +3
      • +2
      • +1
      • 0 Normal
      • -1
      • -2
      • -3 (B&W)
      See Also:

    • TAG_NOISE_REDUCTION

      public static final int TAG_NOISE_REDUCTION
      The type of noise reduction, as a string. Examples include:
      • OFF
      • FPNR
      See Also:

    • TAG_LINEARIZATION_TABLE

      public static final int TAG_LINEARIZATION_TABLE
      See Also:

    • TAG_COLOR_BALANCE

      public static final int TAG_COLOR_BALANCE
      See Also:

    • TAG_LENS_DATA

      public static final int TAG_LENS_DATA
      See Also:

    • TAG_NEF_THUMBNAIL_SIZE

      public static final int TAG_NEF_THUMBNAIL_SIZE
      The NEF (RAW) thumbnail size, as an integer array with two items representing [width,height].
      See Also:

    • TAG_SENSOR_PIXEL_SIZE

      public static final int TAG_SENSOR_PIXEL_SIZE
      The sensor pixel size, as a pair of rational numbers.
      See Also:

    • TAG_UNKNOWN_10

      public static final int TAG_UNKNOWN_10
      See Also:

    • TAG_SCENE_ASSIST

      public static final int TAG_SCENE_ASSIST
      See Also:

    • TAG_DATE_STAMP_MODE

      public static final int TAG_DATE_STAMP_MODE
      See Also:

    • TAG_RETOUCH_HISTORY

      public static final int TAG_RETOUCH_HISTORY
      See Also:

    • TAG_UNKNOWN_12

      public static final int TAG_UNKNOWN_12
      See Also:

    • TAG_CAMERA_SERIAL_NUMBER_2

      public static final int TAG_CAMERA_SERIAL_NUMBER_2
      The camera serial number, as a string.
      • NO= 00002539
      • NO= -1000d71
      • PKG597230621263
      • PKG5995671330625116
      • PKG49981281631130677
      • BU672230725063
      • NO= 200332c7
      • NO= 30045efe
      See Also:

    • TAG_IMAGE_DATA_SIZE

      public static final int TAG_IMAGE_DATA_SIZE
      See Also:

    • TAG_UNKNOWN_27

      public static final int TAG_UNKNOWN_27
      See Also:

    • TAG_UNKNOWN_28

      public static final int TAG_UNKNOWN_28
      See Also:

    • TAG_IMAGE_COUNT

      public static final int TAG_IMAGE_COUNT
      See Also:

    • TAG_DELETED_IMAGE_COUNT

      public static final int TAG_DELETED_IMAGE_COUNT
      See Also:

    • TAG_EXPOSURE_SEQUENCE_NUMBER

      public static final int TAG_EXPOSURE_SEQUENCE_NUMBER
      The number of total shutter releases. This value increments for each exposure (observed on D70).
      See Also:

    • TAG_FLASH_INFO

      public static final int TAG_FLASH_INFO
      See Also:

    • TAG_IMAGE_OPTIMISATION

      public static final int TAG_IMAGE_OPTIMISATION
      The camera's image optimisation, as a string.
      • NORMAL
      • CUSTOM
      • BLACK AND WHITE
      • LAND SCAPE
      • MORE VIVID
      • PORTRAIT
      • SOFT
      • VIVID
      See Also:

    • TAG_SATURATION_2

      public static final int TAG_SATURATION_2
      The camera's saturation level, as a string.
      • NORMAL
      • AUTO
      • ENHANCED
      • MODERATE
      See Also:

    • TAG_DIGITAL_VARI_PROGRAM

      public static final int TAG_DIGITAL_VARI_PROGRAM
      The camera's digital vari-program setting, as a string.
      • AUTO
      • AUTO(FLASH OFF)
      • CLOSE UP
      • LANDSCAPE
      • NIGHT PORTRAIT
      • PORTRAIT
      • SPORT
      See Also:

    • TAG_IMAGE_STABILISATION

      public static final int TAG_IMAGE_STABILISATION
      The camera's digital vari-program setting, as a string.
      • VR-ON
      • VR-OFF
      • VR-HYBRID
      • VR-ACTIVE
      See Also:

    • TAG_AF_RESPONSE

      public static final int TAG_AF_RESPONSE
      The camera's digital vari-program setting, as a string.
      • HYBRID
      • STANDARD
      See Also:

    • TAG_UNKNOWN_29

      public static final int TAG_UNKNOWN_29
      See Also:

    • TAG_UNKNOWN_30

      public static final int TAG_UNKNOWN_30
      See Also:

    • TAG_MULTI_EXPOSURE

      public static final int TAG_MULTI_EXPOSURE
      See Also:

    • TAG_HIGH_ISO_NOISE_REDUCTION

      public static final int TAG_HIGH_ISO_NOISE_REDUCTION
      The camera's high ISO noise reduction setting, as an integer.
      • 0 Off
      • 1 Minimal
      • 2 Low
      • 4 Normal
      • 6 High
      See Also:

    • TAG_UNKNOWN_31

      public static final int TAG_UNKNOWN_31
      See Also:

    • TAG_TONING_EFFECT

      public static final int TAG_TONING_EFFECT
      See Also:

    • TAG_UNKNOWN_33

      public static final int TAG_UNKNOWN_33
      See Also:

    • TAG_UNKNOWN_48

      public static final int TAG_UNKNOWN_48
      See Also:

    • TAG_POWER_UP_TIME

      public static final int TAG_POWER_UP_TIME
      See Also:

    • TAG_AF_INFO_2

      public static final int TAG_AF_INFO_2
      See Also:

    • TAG_FILE_INFO

      public static final int TAG_FILE_INFO
      See Also:

    • TAG_AF_TUNE

      public static final int TAG_AF_TUNE
      See Also:

    • TAG_RETOUCH_INFO

      public static final int TAG_RETOUCH_INFO
      See Also:

    • TAG_PICTURE_CONTROL_2

      public static final int TAG_PICTURE_CONTROL_2
      See Also:

    • TAG_UNKNOWN_51

      public static final int TAG_UNKNOWN_51
      See Also:

    • TAG_PRINT_IMAGE_MATCHING_INFO

      public static final int TAG_PRINT_IMAGE_MATCHING_INFO
      See Also:

    • TAG_NIKON_CAPTURE_DATA

      public static final int TAG_NIKON_CAPTURE_DATA
      Data about changes set by Nikon Capture Editor. Values observed
      See Also:

    • TAG_UNKNOWN_52

      public static final int TAG_UNKNOWN_52
      See Also:

    • TAG_UNKNOWN_53

      public static final int TAG_UNKNOWN_53
      See Also:

    • TAG_NIKON_CAPTURE_VERSION

      public static final int TAG_NIKON_CAPTURE_VERSION
      See Also:

    • TAG_NIKON_CAPTURE_OFFSETS

      public static final int TAG_NIKON_CAPTURE_OFFSETS
      See Also:

    • TAG_NIKON_SCAN

      public static final int TAG_NIKON_SCAN
      See Also:

    • TAG_UNKNOWN_54

      public static final int TAG_UNKNOWN_54
      See Also:

    • TAG_NEF_BIT_DEPTH

      public static final int TAG_NEF_BIT_DEPTH
      See Also:

    • TAG_UNKNOWN_55

      public static final int TAG_UNKNOWN_55
      See Also:

  • Constructor Details

    • NikonType2MakernoteDirectory

      public NikonType2MakernoteDirectory()

  • Method Details

    • getName

      public String getName()
      Description copied from class: Directory
      Provides the name of the directory, for display purposes. E.g. Exif
      Specified by:
      getName in class Directory
      Returns:
      the name of the directory

    • getDecryptedIntArray

      public int[] getDecryptedIntArray(int tagType)
      decryption algorithm adapted from exiftool