.. Copyright Contributors to the OpenImageIO project. SPDX-License-Identifier: CC-BY-4.0 .. _chap-stdmetadata: Metadata conventions #################### The ImageSpec class, described thoroughly in :ref:`sec-ImageSpec`, provides the basic description of an image that are essential across all formats --- resolution, number of channels, pixel data format, etc. Individual images may have additional data, stored as name/value pairs in the `extra_attribs` field. Though literally *anything* can be stored in `extra_attribs` --- it's specifically designed for format- and user-extensibility --- this chapter establishes some guidelines and lays out all of the field names that OpenImageIO understands. Description of the image ======================== .. option:: "ImageDescription" : string The image description, title, caption, or comments. .. option:: "Keywords" : string Semicolon-separated keywords describing the contents of the image. (Semicolons are used rather than commas because of the common case of a comma being part of a keyword itself, e.g., "Kurt Vonnegut, Jr." or "Washington, DC."") .. option:: "Artist" : string The artist, creator, or owner of the image. .. option:: "Copyright" : string Any copyright notice or owner of the image. .. option:: "DateTime" : string The creation date of the image, in the following format: `YYYY:MM:DD HH:MM:SS` (exactly 19 characters long, not including a terminating NULL). For example, 7:30am on Dec 31, 2008 is encoded as `"2008:12:31 07:30:00"`. Usually this is simply the time that the image data was last modified. It may be wise to also store the `"Exif:DateTimeOriginal"` and `"Exif:DateTimeDigitized"` (see Section :ref:`sec-metadata-exif`) to further distinguish the original image and its conversion to digital media. .. option:: "DocumentName" : string The name of an overall document that this image is a part of. .. option:: "Software" : string The software that was used to create the image. .. option:: "HostComputer" : string The name or identity of the computer that created the image. .. _sec-metadata-displayhints: .. _sec-metadata-orientation: Display hints ============= .. option:: "Orientation" : int By default, image pixels are ordered from the top of the display to the bottom, and within each scanline, from left to right (i.e., the same ordering as English text and scan progression on a CRT). But the `"Orientation"` field can suggest that it should be displayed with a different orientation, according to the TIFF/EXIF conventions: === ========================================================================== 1 normal (top to bottom, left to right) 2 flipped horizontally (top to bottom, right to left) 3 rotated :math:`180^\circ` (bottom to top, right to left) 4 flipped vertically (bottom to top, left to right) 5 transposed (left to right, top to bottom) 6 rotated :math:`90^\circ` clockwise (right to left, top to bottom) 7 transverse (right to left, bottom to top) 8 rotated :math:`90^\circ` counter-clockwise (left to right, bottom to top) === ========================================================================== .. option:: "PixelAspectRatio" : float The aspect ratio (:math:`x/y`) of the size of individual pixels, with square pixels being 1.0 (the default). .. option:: "XResolution" : float "YResolution" : float "ResolutionUnit" : string The number of horizontal (*x*) and vertical (*y*) pixels per resolution unit. This ties the image to a physical size (where applicable, such as with a scanned image, or an image that will eventually be printed). Different file formats may dictate different resolution units. For example, the TIFF ImageIO plugin supports `none`, `in`, and `cm`. .. option:: "oiio:Movie" : int If nonzero, a hint that a multi-image file is meant to be interpreted as an animation (i.e., that the subimages are a time sequence). .. option:: "oiio:subimages" : int If nonzero, the number of subimages in the file. Not all image file formats can know this without reading the entire file, and in such cases, this attribute will not be set or will be 0. If the value is present and greater than zero, it can be trusted, but if not, nothing should be inferred and you will have to repeatedly seek to subimages to find out how many there are. .. option:: "FramesPerSecond" : rational For a multi-image file intended to be played back as an animation, the frame refresh rate. (It's technically a rational, but it may be retrieved as a float also, if you are ok with imprecision.) .. _sec-metadata-color: Color information ================= .. option:: "oiio:ColorSpace" : string The name of the color space of the color channels. This can be the name of any documented Color Interop Forum standard token, or any color space, alias, or role known to OpenColorIO. Common values include: - `"lin_rec709_scene"`, : Color pixel values are known to be linear scene-referred and using sRGB/Rec709 color primaries. Note that `"lin_rec709"` is treated as a synonym. - `"lin_ap1_scene"`, `"ACEScg"` : ACEScg color space encoding. - `"lin_ap0_scene"` : ACES2065-1, the recommended ACES space for interchange and archiving. - `"srgb_rec709_scene"` : Using standard (piecewise) sRGB response and primaries. The token `"sRGB"` is treated as a synonym. - `"g22_rec709_scene"` : Rec709/sRGB primaries, but using a response curve corresponding to gamma 2.2. Additionally, `"scene_linear"` is a role that is appropriate for color pixel values are known to be scene-linear and using facility-default color primaries as defined by the OpenColorIO configuration. .. option:: "oiio:BorderColor" : float[nchannels] The color presumed to be filling any parts of the display/full image window that are not overlapping the pixel data window. If not supplied, the default is black (0 in all channels). .. option:: "CICP" : int[4] The CICP color space information, as defined by `ITU-T H.273 `_. This is an array of four integers, with the following meanings: - `[0]` : color primaries - `[1]` : transfer characteristics - `[2]` : matrix coefficients - `[3]` : full range flag .. option:: "ICCProfile" : uint8[] "ICCProfile:...various..." : ...various types... The ICC color profile takes the form of an array of bytes (unsigned 8 bit chars) whose contents and format is as dictated by the ICC specification. The length of the array is the length of the profile blob. When reading images containing ICC profiles, there may be a number of other attributes extracted from the ICC profile (such as `ICCProfile:device_class`). These are for informational convenience only, as they replicate information which is also in the ICCProfile byte array. Be aware that *setting* these attributes will not result in modifying the ICC profile byte array (`"ICCProfile"`), which is considered the sole piece of durable ICC profile information. Disk file format info/hints =========================== .. option:: "oiio:BitsPerSample" : int Number of bits per sample *in the file*. Note that this may not match the reported `ImageSpec::format`, if the plugin is translating from an unsupported format. For example, if a file stores 4 bit grayscale per channel, the `"oiio:BitsPerSample"` may be 4 but the `format` field may be `TypeDesc::UINT8` (because the OpenImageIO APIs do not support fewer than 8 bits per sample). .. option:: "oiio:UnassociatedAlpha" : int Whether the data in the file stored alpha channels (if any) that were unassociated with the color (i.e., color not "premultiplied" by the alpha coverage value). .. option:: "planarconfig" : string `contig` indicates that the file has contiguous pixels (RGB RGB RGB...), whereas `separate` indicate that the file stores each channel separately (RRR...GGG...BBB...). Note that only contiguous pixels are transmitted through the OpenImageIO APIs, but this metadata indicates how it is (or should be) stored in the file, if possible. .. option:: "compression" : string Indicates the type of compression the file uses. Supported compression modes will vary from file format to file format, and each reader/writer plugin should document the modes it supports. If `ImageOutput::open` is called with an ImageSpec that specifies an compression mode not supported by that ImageOutput, it will choose a reasonable default. As an example, the OpenEXR writer supports `none`, `rle`, `zip`, `zips`, `piz`, `pxr24`, `b44`, `b44a`, `dwaa`, or `dwab`. he compression name is permitted to have a quality value to be appended after a colon, for example `dwaa:60`. The exact meaning and range of he quality value can vary between different file formats and compression odes, and some don't support quality values at all (it will be ignored if ot supported, or if out of range). .. option:: "CompressionQuality" : int DEPRECATED(2.1) This is a deprecated methods of separately specifying the compression quality. Indicates the quality of compression to use (0--100), for those plugins and compression methods that allow a variable amount of compression, with higher numbers indicating higher image fidelity. Substituting an `IOPRoxy` for custom I/O overrides ====================================================== Format readers and writers that respond positively to `supports("ioproxy")` have the ability to read or write using an *I/O proxy* object. Among other things, this lets an ImageOutput write the file to a memory buffer rather than saving to disk, and for an ImageInput to read the file from a memory buffer. This behavior is controlled by a special attributes .. option:: "oiio:ioproxy" : pointer Pointer to a `Filesystem::IOProxy` that will handle the I/O. An explanation of how this feature is used may be found in Sections :ref:`sec-imageinput-ioproxy` and :ref:`sec-imageoutput-ioproxy`. In addition to communicating IOProxy information via this attribute, it is also allowed (and probably preferred) to directly supply the IOProxy information via calls to `ImageInput::open()`, `create()`, and `set_ioproxy()`, `ImageOutput::create()` and `set_ioproxy()`, and `ImageBuf::ImageBuf()`, `reset()`, and `set_write_ioproxy()`. Photographs or scanned images ============================= The following metadata items are specific to photos or captured images. .. option:: "Make" : string For captured or scanned image, the make of the camera or scanner. .. option:: "Model" : string For captured or scanned image, the model of the camera or scanner. .. option:: "ExposureTime" : float The exposure time (in seconds) of the captured image. .. option:: "FNumber" : float The f/stop of the camera when it captured the image. Thumbnails / postage stamps / preview images ============================================ Some image file formats allow for storing a `thumbnail` -- a lower-resolution image suitable for an icon or other small preview. These are retrievable separately via `ImageInput::get_thumbnail()`, `ImageBuf::thumbnail()`, or `ImageCache::get_thumbnail()`. In addition, if a thumbnail is available, the `ImageSpec` should also contain the following metadata: .. option:: "thumbnail_width" : int The thumbnail width, in pixels. .. option:: "thumbnail_height" : int The thumbnail height, in pixels. .. option:: "thumbnail_nchannels" : int The number of color channels in the thumbnail image. Texture Information =================== Several standard metadata are very helpful for images that are intended to be used as textures (especially for OpenImageIO's TextureSystem). .. option:: "textureformat" : string The kind of texture that this image is intended to be. We suggest the following names: ===================== ================================================ Plain Texture Ordinary 2D texture Volume Texture 3D volumetric texture Shadow Ordinary *z*-depth shadow map CubeFace Shadow Cube-face shadow map Volume Shadow Volumetric ("deep") shadow map LatLong Environment Latitude-longitude (rectangular) environment map CubeFace Environment Cube-face environment map ===================== ================================================ .. option:: "wrapmodes" : string Give the intended texture *wrap mode* indicating what happens with texture coordinates outside the :math:`[0...1]` range. We suggest the following names: `black`, `periodic`, `clamp`, `mirror`. If the wrap mode is different in each direction, they should simply be separated by a comma. For example, `black` means black wrap in both directions, whereas `clamp,periodic` means to clamp in :math:`u` and be periodic in :math:`v`. .. option:: "fovcot" : float The cotangent (:math:`x/y`) of the field of view of the original image (which may not be the same as the aspect ratio of the pixels of the texture, which may have been resized). .. option:: "worldtocamera" : matrix44 For shadow maps or rendered images this item (of type `TypeDesc::PT_MATRIX`) is the world-to-camera matrix describing the camera position. .. option:: "worldtoscreen" : matrix44 For shadow maps or rendered images this item (of type `TypeDesc::PT_MATRIX`) is the world-to-screen matrix describing the full projection of the 3D view onto a :math:`[-1...1] \times [-1...1]` 2D domain. .. option:: "worldtoNDC" : matrix44 For shadow maps or rendered images this item (of type `TypeDesc::PT_MATRIX`) is the world-to-NDC matrix describing the full projection of the 3D view onto a :math:`[0...1] \times [0...1]` 2D domain. .. option:: "oiio:updirection" : string For environment maps, indicates which direction is "up" (valid values are `y` or `z`), to disambiguate conventions for environment map orientation. .. option:: "oiio:sampleborder" : int If not present or 0 (the default), the conversion from pixel integer coordinates :math:`(i,j)` to texture coordinates :math:`(s,t)` follows the usual convention of :math:`s = (i+0.5)/\mathit{xres}` and :math:`t = (j+0.5)/\mathit{yres}`. However, if this attribute is present and nonzero, the first and last row/column of pixels lie exactly at the :math:`s` or :math:`t = 0` or :math:`1` boundaries, i.e., :math:`s = i/(\mathit{xres}-1)` and :math:`t = j/(\mathit{yres}-1)`. .. option:: "oiio:ConstantColor" : string If present, is a hint that the texture has the same value in all pixels, and the metadata value is a string containing the channel values as a comma-separated list (no spaces, for example: `0.73,0.9,0.11,1.0`). .. option:: "oiio:AverageColor" : string If present, is a hint giving the *average* value of all pixels in the texture, as a string containing a comma-separated list of the channel values (no spaces, for example: `0.73,0.9,0.11,1.0`). .. option:: "oiio:SHA-1" : string f present, is a 40-byte SHA-1 hash of the input image (possibly salted with arious maketx options) that can serve to quickly compare two separate extures to know if they contain the same pixels. While it's not, echnically, 100% guaranteed that no separate textures will match, it's so stronomically unlikely that we discount the possibility (you'd be rendering ovies for centuries before finding a single match). .. _sec-metadata-exif: Exif metadata ============= .. % FIXME -- unsupported/undocumented: ExifVersion, FlashpixVersion, % ComponentsConfiguration, MakerNote, UserComment, RelatedSoundFile, % OECF, SubjectArea, SpatialFrequencyResponse, % CFAPattern, DeviceSettingDescription % % SubjectLocation -- unsupported, but we could do it The following Exif metadata tags correspond to items in the "standard" set of metadata. ============== ================================================== Exif tag OpenImageIO metadata convention ============== ================================================== ColorSpace (reflected in "oiio:ColorSpace") ExposureTime `ExposureTime` FNumber `FNumber` ============== ================================================== The other remaining Exif metadata tags all include the ``Exif:`` prefix to keep it from clashing with other names that may be used for other purposes. .. option:: "Exif:ExposureProgram" : int The exposure program used to set exposure when the picture was taken: === ============================================================== 0 unknown 1 manual 2 normal program 3 aperture priority 4 shutter priority 5 Creative program (biased toward depth of field) 6 Action program (biased toward fast shutter speed) 7 Portrait mode (closeup photo with background out of focus) 8 Landscape mode (background in focus) === ============================================================== .. option:: "Exif:SpectralSensitivity" : string The camera's spectral sensitivity, using the ASTM conventions. .. option:: "Exif:ISOSpeedRatings" : int The ISO speed and ISO latitude of the camera as specified in ISO 12232. .. option:: "Exif:DateTimeOriginal" : string "Exif:DateTimeDigitized" : string Date and time that the original image data was generated or captured, and the time/time that the image was stored as digital data. Both are in `YYYY:MM:DD HH:MM:SS` format. To clarify the role of these (and also with respect to the standard `DateTime` metadata), consider an analog photograph taken in 1960 (`Exif:DateTimeOriginal`), which was scanned to a digital image in 2010 (`Exif:DateTimeDigitized`), and had color corrections or other alterations performed in 2015 (`DateTime`). .. option:: "Exif:CompressedBitsPerPixel" : float The compression mode used, measured in compressed bits per pixel. .. option:: "Exif:ShutterSpeedValue" : float Shutter speed, in APEX units: :math:`-\log_2(\mathit{exposure time})` .. option:: "Exif:ApertureValue" : float Aperture, in APEX units: :math:`2 \log_2 (\mathit{fnumber})` .. option:: "Exif:BrightnessValue" : float Brightness value, assumed to be in the range of :math:`-99.99` -- :math:`99.99`. .. option:: "Exif:ExposureBiasValue" : float Exposure bias, assumed to be in the range of :math:`-99.99` -- :math:`99.99`. .. option:: "Exif:MaxApertureValue" : float Smallest F number of the lens, in APEX units: :math:`2 \log_2 (\mathit{fnumber})` .. option:: "Exif:SubjectDistance" : float Distance to the subject, in meters. .. option:: "Exif:MeteringMode" : int The metering mode: === =============================================== 0 unknown 1 average 2 center-weighted average 3 spot 4 multi-spot 5 pattern 6 partial 255 other === =============================================== .. option:: "Exif:LightSource" : int The kind of light source: === =============================================== 0 unknown 1 daylight 2 tungsten (incandescent light) 4 flash 9 fine weather 10 cloudy weather 11 shade 12 daylight fluorescent (D 5700-7100K) 13 day white fluorescent (N 4600-5400K) 14 cool white fuorescent (W 3900 - 4500K) 15 white fluorescent (WW 3200 - 3700K) 17 standard light A 18 standard light B 19 standard light C 20 D55 21 D65 22 D75 23 D50 24 ISO studio tungsten 255 other light source === =============================================== .. option:: "Exif:Flash" int} A sum of: === ============================================================== 1 if the flash fired 0 no strobe return detection function 4 strobe return light was not detected 6 strobe return light was detected 8 compulsory flash firing 16 compulsory flash suppression 24 auto-flash mode 32 no flash function (0 if flash function present) 64 red-eye reduction supported (0 if no red-eye reduction mode) === ============================================================== .. option:: "Exif:FocalLength" : float Actual focal length of the lens, in mm. .. option:: "Exif:SecurityClassification" : string Security classification of the image: `C` = confidential, `R` = restricted, `S` = secret, `T` = top secret, `U` = unclassified. .. option:: "Exif:ImageHistory" : string Image history. .. option:: "Exif:SubsecTime" : string Fractions of a second to augment the `"DateTime"` (expressed as text of the digits to the right of the decimal). .. option:: "Exif:SubsecTimeOriginal" : string Fractions of a second to augment the `Exif:DateTimeOriginal` (expressed as text of the digits to the right of the decimal). .. option:: "Exif:SubsecTimeDigitized" : string Fractions of a second to augment the `Exif:DateTimeDigital` (expressed as text of the digits to the right of the decimal). .. option:: "Exif:PixelXDimension" : int "Exif:PixelYDimension" : int The *x* and *y* dimensions of the valid pixel area. .. option:: "Exif:FlashEnergy" : float Strobe energy when the image was captures, measured in Beam Candle Power Seconds (BCPS). .. option:: "Exif:FocalPlaneXResolution" : float "Exif:FocalPlaneYResolution" : float "Exif:FocalPlaneResolutionUnit" : int The number of pixels in the *x* and *y* dimension, per resolution unit. The codes for resolution units are: === ============================================================== 1 none 2 inches 3 cm 4 mm 5 :math:`\mu m` === ============================================================== .. option: "Exif:SubjectLocation" : int} // FIXME: short[2] .. option:: "Exif:ExposureIndex" : float The exposure index selected on the camera. .. option:: "Exif:SensingMethod" : int The image sensor type on the camra: === ============================================================== 1 undefined 2 one-chip color area sensor 3 two-chip color area sensor 4 three-chip color area sensor 5 color sequential area sensor 7 trilinear sensor 8 color trilinear sensor === ============================================================== .. option:: "Exif:FileSource" : int The source type of the scanned image, if known: === ============================================================== 1 film scanner 2 reflection print scanner 3 digital camera === ============================================================== .. option:: "Exif:SceneType" : int Set to 1, if a directly-photographed image, otherwise it should not be present. .. option:: "Exif:CustomRendered" : int Set to 0 for a normal process, 1 if some custom processing has been performed on the image data. .. option:: "Exif:ExposureMode" : int The exposure mode: === ============================================================== 0 auto 1 manual 2 auto-bracket === ============================================================== .. option:: "Exif:WhiteBalance" : int Set to 0 for auto white balance, 1 for manual white balance. .. option:: "Exif:DigitalZoomRatio" : float The digital zoom ratio used when the image was shot. .. option:: "Exif:FocalLengthIn35mmFilm" : int The equivalent focal length of a 35mm camera, in mm. .. option:: "Exif:SceneCaptureType" : int The type of scene that was shot: === ============================================================== 0 standard 1 landscape 2 portrait 3 night scene === ============================================================== .. option:: "Exif:GainControl" : float The degree of overall gain adjustment: === ============================================================== 0 none 1 low gain up 2 high gain up 3 low gain down 4 high gain down === ============================================================== .. option:: "Exif:Contrast" : int The direction of contrast processing applied by the camera: === ============================================================== 0 normal 1 soft 2 hard === ============================================================== .. option:: "Exif:Saturation" : int The direction of saturation processing applied by the camera: === ============================================================== 0 normal 1 low saturation 2 high saturation === ============================================================== .. option:: "Exif:Sharpness" : int The direction of sharpness processing applied by the camera: === ============================================================== 0 normal 1 soft 2 hard === ============================================================== .. option:: "Exif:SubjectDistanceRange" : int The distance to the subject: === ============================================================== 0 unknown 1 macro 2 close 3 distant === ============================================================== .. option:: "Exif:ImageUniqueID" : string A unique identifier for the image, as 16 ASCII hexadecimal digits representing a 128-bit number. .. option:: "Exif:ImageTitle" : string Title of the image. .. option:: "Exif:Photographer" : string The name of the photographer. This may be different from the "Artist" field. .. option:: "Exif:ImageEdtor" : string The name of the main person who edited the image. .. option:: "Exif:CameraFirmware" : string The name and version of the firmware of the camera that captured the image. .. option:: "Exif:RAWDevelopingSoftware" : string The name and version of the software that developed the RAW image. .. option:: "Exif:ImageEditingSoftware" : string The name and version of any image editing software that was used to process or edit the image. .. option:: "Exif:MetadataEditingSoftware" : string The name and version of any image editing software that was used to edit the image metadata but not the pixels. .. option:: "Exif:CompositeImage" : int Indicates whether the recorded image is a composite image (generated from capturing multiple, tentatively recorded, source images). === ============================================================== 0 unknown 1 non-composite image 2 general composite image 3 composite image captured when shooting === ============================================================== .. option:: "Exif:SourceImageNumberOfCompositeImage" : ushort[2] If a composite image, the first value is the number of source images captured (at least 2) and the second value is the number of those source images ultimately used in the comopsite image. .. option:: "Exif:SourceImageExposureTimesOfCompositeImage" This is currently unsupported by OpenImageIO. GPS Exif metadata ================= The following GPS-related Exif metadata tags correspond to items in the "standard" set of metadata. .. option:: "GPS:LatitudeRef" : string Whether the `GPS:Latitude` tag refers to north or south: `N` or `S`. .. option:: "GPS:Latitude" : float[3] The degrees, minutes, and seconds of latitude (see also `GPS:LatitudeRef`). .. option:: "GPS:LongitudeRef" : string Whether the `GPS:Longitude` tag refers to east or west: `E` or a `W`. .. option:: "GPS:Longitude" : float[3] The degrees, minutes, and seconds of longitude (see also `GPS:LongitudeRef`). .. option:: "GPS:AltitudeRef" : string A value of 0 indicates that the altitude is above sea level, 1 indicates below sea level. .. option:: "GPS:Altitude" : float Absolute value of the altitude, in meters, relative to sea level (see `GPS:AltitudeRef` for whether it's above or below sea level). .. option:: "GPS:TimeStamp" : float[3] Gives the hours, minutes, and seconds, in UTC. .. option:: "GPS:Satellites" : string Information about what satellites were visible. .. option:: "GPS:Status" : string `A` indicates a measurement in progress, `V` indicates measurement interoperability. .. option:: "GPS:MeasureMode" : string `2` indicates a 2D measurement, `3` indicates a 3D measurement. .. option:: "GPS:DOP" : float Data degree of precision. .. option:: "GPS:SpeedRef" : string Indicates the units of the related `GPS:Speed` tag: `K` for km/h, `M` for miles/h, `N` for knots. .. option:: "GPS:Speed" : float Speed of the GPS receiver (see `GPS:SpeedRef` for the units). .. option:: "GPS:TrackRef" : string Describes the meaning of the `GPS:Track` field: `T` for true direction, `M` for magnetic direction. .. option:: "GPS:Track" : float Direction of the GPS receiver movement (from 0--359.99). The related `GPS:TrackRef` indicate whether it's true or magnetic. .. option:: "GPS:ImgDirectionRef" : string Describes the meaning of the `GPS:ImgDirection` field: `T` for true direction, `M` for magnetic direction. .. option:: "GPS:ImgDirection" : float Direction of the image when captured (from 0--359.99). The related `GPS:ImgDirectionRef` indicate whether it's true or magnetic. .. option:: "GPS:MapDatum" : string The geodetic survey data used by the GPS receiver. .. option:: "GPS:DestLatitudeRef" : string Whether the `GPS:DestLatitude` tag refers to north or south: `N` or `S`. .. option:: "GPS:DestLatitude" : float[3] The degrees, minutes, and seconds of latitude of the destination (see also `GPS:DestLatitudeRef`). .. option:: "GPS:DestLongitudeRef" : string Whether the `GPS:DestLongitude` tag refers to east or west: `E` or `W`. .. option:: "GPS:DestLongitude" : float[3] The degrees, minutes, and seconds of longitude of the destination (see also `GPS:DestLongitudeRef`). .. option:: "GPS:DestBearingRef" : string Describes the meaning of the `GPS:DestBearing` field: `T` for true direction, `M` for magnetic direction. .. option:: "GPS:DestBearing" : float Bearing to the destination point (from 0--359.99). The related `GPS:DestBearingRef` indicate whether it's true or magnetic. .. option:: "GPS:DestDistanceRef" : string Indicates the units of the related `GPS:DestDistance` tag: `K` for km, `M` for miles, `N` for knots. .. option:: "GPS:DestDistance" : float Distance to the destination (see `GPS:DestDistanceRef` for the units). .. option:: "GPS:ProcessingMethod" : string Processing method information. .. option:: "GPS:AreaInformation" : string Name of the GPS area. .. option:: "GPS:DateStamp" : string Date according to the GPS device, in format `YYYY:MM:DD`. .. option:: "GPS:Differential" : int If 1, indicates that differential correction was applied. .. option:: "GPS:HPositioningError" : float Positioning error. IPTC metadata ============= The IPTC (International Press Telecommunications Council) publishes conventions for storing image metadata, and this standard is growing in popularity and is commonly used in photo-browsing programs to record captions and keywords. IPTC metadata fields should use the following names, prefixed with `IPTC:` to avoid conflicts with other plugins or standards. .. option:: "IPTC:ObjecTypeReference" : string Object type reference. .. option:: "IPTC:ObjectAttributeReference" : string Object attribute reference. .. option:: "IPTC:ObjectName" : string The name of the object in the picture. .. option:: "IPTC:EditStatus" : string Edit status. .. option:: "IPTC:SubjectReference" : string Subject reference. .. option:: "IPTC:Category" : string Category. .. option:: "IPTC:Keywords" : string Semicolon-separated keywords describing the contents of the image. .. option:: "IPTC:ContentLocationCode" : string Code for content location. .. option:: "IPTC:ContentLocationName" : string Name of content location. .. option:: "IPTC:ReleaseDate" : string "IPTC:ReleaseTime" : string Release date and time. .. option:: "IPTC:ExpirationDate" : string "IPTC:ExpirationTime" : string Expiration date and time. .. option:: "IPTC:ExposureTime" : string The exposure time (in seconds) of the captured image. .. option:: "IPTC:Instructions" : string Special instructions for handling the image. .. option:: "IPTC:ReferenceService" : string "IPTC:ReferenceDate" : string "IPTC:ReferenceNumber" : string Reference date, service, and number. .. option:: "IPTC:DateCreated" : string "IPTC:TimeCreated" : string Date and time that the image was created. .. option:: "IPTC:DigitalCreationDate" : string "IPTC:DigitalCreationTime" : string Date and time that the image was digitized. .. option:: "IPTC:ProgramVersion" : string The version number of the creation software. .. option:: "IPTC:Creator" : string The artist, creator, or owner of the image. .. option:: "IPTC:AuthorsPosition" : string The job title or position of the creator of the image. .. option:: "IPTC:City" : string "IPTC:Sublocation" : string "IPTC:State" : string "IPTC:Country" : string "IPTC:CountryCode" : string The city, sublocation within the city, state, country, and country code of the location of the image. .. option:: "IPTC:Headline" : string Any headline that is meant to accompany the image. .. option:: "IPTC:Provider" : string The provider of the image, or credit line. .. option:: "IPTC:Source" : string The source of the image. .. option:: "IPTC:CopyrightNotice" : string Any copyright notice for the image. .. option:: "IPTC:Contact" : string The contact information for the image (possibly including name, address, email, etc.). .. option:: "IPTC:Caption" : string A caption for the image. .. option:: "IPTC:CaptionWriter" : string The name of the person who wrote the caption or description of the image. .. option:: "IPTC:JobID" : string "IPTC:MasterDocumentID" : string "IPTC:ShortDocumentID" : string "IPTC:UniqueDocumentID" : string "IPTC:OwnerID" : string Various identification tags. .. option:: "IPTC:Prefs" : string "IPTC:ClassifyState" : string "IPTC:SimilarityIndex" : string Who knows what the heck these are? .. option:: "IPTC:DocumentNotes" : string Notes about the image or document. .. option:: "IPTC:DocumentHistory" : string The history of the image or document. References for more information on IPTC metadata: * https://www.iptc.org/std/photometadata/specification/IPTC-PhotoMetadata * https://www.iptc.org/std/photometadata/specification/IPTC-PhotoMetadata#iptc-core-schema-1-5-specifications This is the one where you can find the length limits * ExifTool's documentation about IPTC tags (caveat: not a definitive reference, could be outdated or incorrect): https://exiftool.org/TagNames/IPTC.html SMPTE metadata ============== .. option:: "smpte:TimeCode" : int[2] SMPTE time code, encoded as an array of 2 32-bit integers (as a `TypeDesc`, it will be tagged with vecsemantics `TIMECODE`). .. option:: "smpte:KeyCode" : int[7] SMPTE key code, encoded as an array of 7 32-bit integers (as a `TypeDesc`, it will be tagged with vecsemantics `KEYCODE`). Extension conventions ===================== To avoid conflicts with other plugins, or with any additional standard metadata names that may be added in future versions of OpenImageIO, it is strongly advised that writers of new plugins should prefix their metadata with the name of the format, much like the `"Exif:"` and `"IPTC:"` metadata.