Tech Tip: Extracting blocks of picture metadata
PRODUCT: 4D | VERSION: 12.2 | PLATFORM: Mac & Win
Published On: August 18, 2011
As of 4D v12, picture metadata can be extracted from a picture field or variable using the GET PICTURE METADATA command. This command is capable, among other things, of returning an entire block of metadata with a single call. A block being "TIFF", "EXIF", "GPS" or "IPTC".
Given this new command, it is a relatively straightforward task to extract all picture metadata. Here is a sample method that extracts all the metadata from a picture file. In this example, the method simply generates an XML file with all of the metadata.
Here is an example of the XML output, when this code is run on a picture variable which contains some metadata:
Here is another example showing what the XML will look like if the picture contained no metadata.
Notice that all 4 blocks are empty.
Given this new command, it is a relatively straightforward task to extract all picture metadata. Here is a sample method that extracts all the metadata from a picture file. In this example, the method simply generates an XML file with all of the metadata.
| C_STRING(16;$xml_root;$xml_TIFF;$xml_GPS;$xml_EXIF;$xml_IPTC) C_PICTURE($1;$image_i) $image_i:=$1 $xml_root:=DOM Create XML Ref("Root") // Creation of an XML DOM tree $xml_TIFF:=DOM Create XML element($xml_root;"/Root/TIFF") GET PICTURE METADATA($image_i;"TIFF";$xml_TIFF) $xml_GPS:=DOM Create XML element($xml_root;"/Root/GPS") GET PICTURE METADATA($image_i;"GPS";$xml_GPS) $xml_EXIF:=DOM Create XML element($xml_root;"/Root/EXIF") GET PICTURE METADATA($image_i;"EXIF";$xml_EXIF) $xml_IPTC:=DOM Create XML element($xml_root;"/Root/IPTC") GET PICTURE METADATA($image_i;"IPTC";$xml_IPTC) DOM EXPORT TO FILE($xml;Get 4D folder(Database Folder)+"image_meta.xml") DOM CLOSE XML($xml) |
Here is an example of the XML output, when this code is run on a picture variable which contains some metadata:
| <?xml version="1.0" encoding="UTF-8" standalone="no" ?> <Root> <TIFF DateTime="2004-03-10T09:37:27Z" Make="Canon" Model="Canon DIGITAL IXUS 400" Orientation="1" ResolutionUnit="2" Software="Adobe Photoshop 7.0" XResolution="180" YResolution="180"/> <GPS/> <EXIF ApertureValue="5.65625" ColorSpace="1" ComponentsConfiguration="1;2;3;0" CompressedBitsPerPixel="5" CustomRendered="0" DateTimeDigitized="2004-03-09T17:47:30Z" DateTimeOriginal="2004-03-09T17:47:30Z" DigitalZoomRatio="1" ExifVersion="0220" ExposureBiasValue="0" ExposureMode="0" ExposureTime="0.0025" FNumber="7.1" FileSource="3" Flash="24" FlashPixVersion="0100" FocalLength="7.40625" FocalPlaneResolutionUnit="2" FocalPlaneXResolution="8114.2857142857" FocalPlaneYResolution="8114.2857142857" MaxApertureValue="2.96875" MeteringMode="5" PixelXDimension="2272" PixelYDimension="1704" SceneCaptureType="0" SensingMethod="2" ShutterSpeedValue="8.65625" WhiteBalance="0"/> <IPTC/> </Root> |
Here is another example showing what the XML will look like if the picture contained no metadata.
| <?xml version="1.0" encoding="UTF-8" standalone="no" ?> <Root> <TIFF/> <GPS/> <EXIF/> <IPTC/> </Root> |
Notice that all 4 blocks are empty.