JPEG (.jpg, .jpeg)

Background

    ▪ MIME type: image/jpeg
    ▪ JPEG raster image and compression format.
    ▪ Commonly used for photographic images by digital cameras and on the web.
    ▪ JPEG is an acronym for Joint Photographic Experts Group.
    ▪ Supports Grayscale, RGB, and CMYK color spaces.
    ▪ Stores images as bitmaps at a resolution of 8 bits per color channel.
    ▪ Binary format.
    ▪ Uses a lossy compression method based on an 8×8 block-sized discrete cosine transform.
    ▪ Supports different compression levels.

Import and Export

  • Import["file.jpg"] imports a JPEG file, returning an image.
  • Import["file.jpg",elem] imports the specified element from a JPEG file.
  • The import format can be specified with Import["file","JPEG"] or Import["file",{"JPEG",elem,…}].
  • Export["file.jpg",expr] exports an image, graphics, or any other expression as an image to a JPEG file.
  • Image objects are by default exported at their full raster size. Graphics and other arbitrary expressions are exported using the same raster size as their displayed form.
  • See the reference pages for full general information on Import and Export.
  • ImportString and ExportString support the JPEG format.

Notebook Interface

  • In the notebook front end, Insert ▶ Picture and the Open menu allow the import of a JPEG file into a cell.
  • Save Selection As exports the selected part of a notebook as a JPEG file.

Elements

  • General Import elements:
  • "Elements" list of elements and options available in this file
    "Rules"full list of rules for each element and option
    "Options"list of rules for options, properties, and settings
  • Data representation elements:
  • "ColorMap"color reduction palette
    "Data"array of pixel values
    "Graphics"raster image, given as a Graphics object
    "Image"raster image, given as an Image object
    "RawData"array of color map indices
    {"Thumbnail",size}thumbnail of the first image (default size = Small)
  • Import and Export by default use the "Image" element for the JPEG format.
  • Advanced Import elements:
  • "BitDepth"bits used to represent each color channel in the file
    "CameraTopOrientation"orientation of the camera when the picture was taken
    "Channels"
  • the number of color channels used in the file
    • "ColorProfileData"embedded color profile, given as a ColorProfileData object
    "ColorSpace"color encoding used in the file
    "FlashUsed"
  • whether the flash was fired
    • "GeoPosition"latitude and longitude represented as a GeoPosition object
    "GPSDateTime"
  • image creation date and time registered by GPS
    • "ImageSize"raster dimensions
    "RedEyeCorrection"whether a red-eye correction was performed
    "Summary"
  • summary of the file
  • Metadata elements:
  • "Exif"formatted Exif (Exchange image file format)
    "IPTC"formatted IPTC (International Press Telecommunications Council)
    "XMP"formatted XMP (Extensible metadata platform)
  • Raw metadata, as stored in the file, can be imported using "RawExif", "RawXMP" and "RawIPTC" elements which are returned in an association.
  • All Exif and IPTC tags can be imported individually. Common tags include:
  • "ApertureValue"lens aperture
    "Artist"photographer or image creator
    "DateTime"image creation date and time
    "ExposureTime"exposure time, given in seconds
    "FlashInfo"
  • flash information: flash fired, red-eye correction, etc.
    • "FNumber"F number
    "FocalLength"actual focal length of the lens, given in millimeters
    "GPSAltitude"altitude of the GPS position
    "GPSLatitude"latitude of the GPS position
    "GPSLongitude"longitude of the GPS position
    "Make"manufacturer of the recording equipment
    "Model"model name or model number of the equipment
    "Software"name and version of the software or firmware of the camera or image input device used to generate the image

Options

  • Import and Export option:
  • ImageResolutionAutomaticresolution values for import and export
    ImageSizeAutomaticoverall image size
    IncludeMetaInformationAllmetadata types to import and export
    "ImageTopOrientation"Automaticorientation of the image as stored in the file
  • Import option:
  • "TakeRows"{1,-1}rows to import
  • Export options:
  • "ColorSpace""RGB"color encoding to be used in the file
    "CompressionLevel"0.25sets the JPEG compression parameter
    "Progressive"Falsewhether to store the image in a way that allows progressive display while the file is being loaded
    "Smoothing"0the JPEG smoothing parameters, given as a number in the range 0 (no smoothing) to 1
    ImageFormattingWidth$ImageFormattingWidthtarget width when formatting an object
  • Supported "ColorSpace" settings are: "Grayscale", "RGB", and "CMYK". Using "ColorSpace"->Automatic, Export attempts to create a JPEG file with the same color space.
  • The value of "CompressionLevel" can be in the range from 0 to 1, with larger values resulting in smaller file sizes but lower-quality encodings.

Examples

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Basic Examples  (3)

Import a JPEG image as an image:

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Summary of an image:

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Export an RGB image to JPEG:

In[1]:=
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Scope  (3)

Import Elements  (34)

Import Options  (7)

Export Options  (5)

See Also

"JPEG2000"  "PNG"  "TIFF"  "Raw"  "WebP"  "ICC"

Tutorials

Introduced in 1999
(4.0)
| Updated in 2016
(11.0)