objectStats(field, type)

objectStats(field, imageName, propertyType)

Returns the Images/Files field statistics or the metadata encoded in JPG/TIFF/PNG images (e.g. by digital cameras).

objectStats(field, type)

type = 0 - returns the number of objects
type = 1 - returns the size in bytes of the biggest object in a field
type = 2 - returns the size in bytes of the smallest object in a field
type = 3 - returns 1 if a field contains images (in format supported by GS-Base) or 0 otherwise.
To obtain the total physical size of the Images/Files fields, use the len() function.

objectStats(field, imageName, propertyType)

NOTE: this functions should be used in calculated Text fields.
imageName - if there are multiple images in a field, you can specify a name of given image; if you specify an empty string, the first image from a field will be used
propertyType - a numeric property code; to generate a list of all possible codes for a given image, specify -1.

=objectStats(files, 0)
=objectStats(images, 1)
=objectStats(images, "", hex2dec("132")) returns the 0x132 property value - a date
=objectStats(images, "some_image.jpg", hex2dec("132")) returns the 0x132 property value for a given image
=objectStats(images, "", -1) returns the list of all properties encoded in a given image.

Property values can be read for JPG/TIFF/EXIF/PNG images. A picture taken by a digital camera can contain for example the following tags:

ImageWidth(0x100)
ImageHeight(0x101)
EquipMake(0x10f)
EquipModel(0x110)
Orientation(0x112)
XResolution(0x11a)
YResolution(0x11b)
ResolutionUnit(0x128)
SoftwareUsed(0x131)
DateTime(0x132)
YCbCrPositioning(0x213)
ExifExposureTime(0x829a)
ExifFNumber(0x829d)
ExifExposureProg(0x8822)
ExifISOSpeed(0x8827)
ExifVer(0x9000)
ExifDTOrig(0x9003)
ExifDTDigitized(0x9004)
ExifCompConfig(0x9101)
ExifShutterSpeed(0x9201)
ExifAperture(0x9202)
ExifBrightness(0x9203)
ExifExposureBias(0x9204)
ExifMaxAperture(0x9205)
ExifSubjectDist(0x9206)
ExifMeteringMode(0x9207)
ExifFlash(0x9209)
ExifFocalLength(0x920a)
ExifMakerNote(0x927c)
ExifDTSubsec(0x9290)
ExifDTOrigSS(0x9291)
ExifDTDigSS(0x9292)
ExifFPXVer(0xa000)
ExifColorSpace(0xa001)
ExifPixXDim(0xa002)
ExifPixYDim(0xa003)
ExifSensingMethod(0xa217)
ExifSceneType(0xa301)
GpsVer(0x0)
GpsLatitudeRef(0x1)
GpsLatitude(0x2)
GpsLongitudeRef(0x3)
GpsLongitude(0x4)
GpsAltitudeRef(0x5)
GpsAltitude(0x6)
GpsGpsTime(0x7)
GpsGpsDop(0xb)
ThumbnailData(0x501b)
ThumbnailImageWidth(0x5020)
ThumbnailImageHeight(0x5021)
ThumbnailCompression(0x5023)
ThumbnailOrientation(0x5029)
ThumbnailResolutionX(0x502d)
ThumbnailResolutionY(0x502e)
ThumbnailResolutionUnit(0x5030)
JPEGInterFormat(0x201)
JPEGInterLength(0x202)
ChrominanceTable(0x5091)
LuminanceTable(0x5090)
ICCProfile(0x8773)

For the full list of the possible tags please use any i-net search engine and search for the official specification the image / picture metadata tags.