Image Metadata

ERDAS IMAGINE Help

HGD_Variant
16.5.1
HGD_Product
ERDAS IMAGINE
HGD_Portfolio_Suite
Producer

View and edit the metadata of ERDAS IMAGINE image files and other raster data in the Image Metadata dialog. Here you can view much information stored in the image including statistics, map projection information, pixel digital numbers, and metadata header information.

SHARED Tip To view the image metadata for large (>50 bands) hyperspectral images that are loaded from an Oracle Database, ask your DBA to increase the maximum open cursor limit for the selected database.

Editing Image Metadata

This information should be modified with caution because ERDAS IMAGINE programs use this information for data input. If it is incorrect, there will be errors in the output data for these programs. Changes are automatically applied immediately. You are not prompted before the file is changed.

To edit the image metadata, first clear the image from the View. Then you can edit metadata and reload the edited image in the View. When an image is open in the View, the file is locked and cannot be edited.

To learn how to review or edit metadata, see View Image Metadata, Set or Clear NoData Value, Save GeoTIFF Tags when Photo Editing, and Create a World File workflows.

Save Pyramid Layers and Auxiliary Files to a Separate Directory

You can create pyramid layers and auxiliary files to a separate directory if the directory where the data resides is restricted (read-only). In the Preference Editor > Image Files (General) category, the preference Directory for Writable Proxy Datasets names the default directory. You can change the path and directory name to a directory of your choice.

Dialog Description

This dialog opens when you click Home tab > document_information Metadata or click Home tab > document_information Metadata > View/Edit Image Metadata.

This dialog may contain one or more of the following tabs (see below for details):

  • General
  • Projection
  • Histogram
  • Pixel data
  • File History
  • Elevation Info
  • NITF Info
  • GCPTable
  • ECW or JP2 Info
  • TIFF Info or BigTIFF Info
  • Sensor Name Header

In addition, depending on the type of file opened, you may see one or more tabs associated with metadata nodes specific to the file or band. This is often information collected by an importer or other application and made part of the data set. Here are just a few examples:

Classification_Info

SensorName

LIDAR Metadata

NLAPS_Header

RADAR_Subset

RapidEye Info

SAR_Metadata

JP2_GML

SHARED Tip To scroll to each tab, press Ctrl+Tab on your keyboard.

Image Metadata Menu Bar

File -Open the File options menu. The keyboard shortcut is Alt+F.

Open -Open a file. The File Selector opens. The keyboard shortcut is Ctrl+O.

New Open a new Image Metadata dialog. The keyboard shortcut is Ctrl+N.

Print Options -Set up print parameters. The Print Info dialog opens.

Print Print using Print Options set in Print Info dialog. A Print dialog opens. The keyboard shortcut is Ctrl+P.

Print To File -Print Print Options set in Print Info dialog to an ASCII text file. The File Selector opens. The keyboard shortcut is Ctrl+I.

Close -Close this Image Metadata dialog. The keyboard shortcut is Ctrl+D.

Close all -Close all Image Metadata dialogs.

Edit - Open the Edit options menu. These options are disabled if you do not have write permissions to the file. The keyboard shortcut is Alt+E.

Change Layer Name -Change the name of a layer. The Rename Layer dialog opens.

Change Layer Type -Change the current layer type to continuous if it is thematic or to thematic if it is continuous.

This may be necessary if you want to perform a function on a layer that is available only to certain layer types, such as recoding, which can be performed only on thematic layers.

Requirements to Change a Continuous File to Thematic

  • You must have write access to the file
  • The file must have exactly one layer
  • The data type of the layer must be an unsigned integer type
  • Statistics must have been computed using a 1,1 skip factor
  • Statistics must have been computed using a direct bin function
  • The raster DLL for the file must support thematic files

SHARED Tip When a continuous file is changed to thematic in Image Metadata, statistics are recalculated using a skip factor of 1 so that all data values present in the file are accounted for. The Skip Factor shows in the Image Metadata dialog as Skip Factor X and Skip Factor Y. Previous versions of ERDAS IMAGINE allowed files to be changed to thematic without statistics being recalculated. These files may cause problems in some Image Interpretation functions such as Matrix and Summary.

If you have files such as this, you may need to manually recompute statistics using Image Metadata before using these files as input to Matrix or Summary.

Delete Current Layer -Remove any layer except the last one.

Set/Clear NoData Value - Set, change, or clear the NoData value for the image. The Set or Clear NoData Value dialog opens.

Compute Pyramid Layers/Statistics -Create reduced subsampled raster layers, and compute statistics on specific regions or layers of the image file. Using the pyramid layer option reduces processing and display time for large images. The Pyramid Layer/Statistics Generation Options dialog opens.

Optimize Pyramid Layers - Transform legacy metadata about image pyramids into a more optimized form for display. This command should be run on any legacy dataset that has pyramid layers available. New pyramids generated will already be in optimized form.

Delete Pyramid Layers -Remove the pyramid layers.

Change Map Model Modify map information such as pixel size, how map units are expressed, or map projection (non-calibrated images only). The Change Map Info dialog opens.

Set Elevation Source - This option is available for an image calibrated to a 3D geometric model. When available, the Set Elevation Source dialog opens.

Delete Map Model - Delete map information in either the current layer or in all layers of the image. A warning dialog opens, describing that any calibration and/or projection information will also be lost, and layers will revert to a pixel map system. If you click Yes, then map information will be deleted for all layers. If you click No, then map information will be deleted for the current layer. If you click Cancel, map information will not be deleted.

Import Map Model - Import map model information from the associated .aux file to the current layer or to all layers of the image. If you click Yes, then map information will be imported to all layers. If you click No, then map information will be imported to the current layer. If you click Cancel, map information will not be imported.

Export Map Model - Export map model information from the current layer or from all layers to an associated .aux file. If you click Yes, then map information from all layers will be exported. If you click No, then map information from the current layer will be exported. If you click Cancel, map information will not be exported.

Store GeoTIFF tags in separate .aux file

The Import Map Model and Export Map Model options assist you in using GeoTIFF images in image enhancement software products such as Adobe Photoshop. These software products are known to remove the GeoTIFF tags when the image is saved.

In ERDAS IMAGINE, you can store the GeoTIFF tags in a separate file and reapply them later. Select the Export Map Model option to store the GeoTIFF tags in an .aux file, then use the other software products as needed. When finished, use Import Map Model option in ERDAS IMAGINE to import the GeoTIFF tags back into the TIFF image metadata, making them GeoTIFF images once again.

Add/Change Projection -Modify the map projection information. The Projection Chooser dialog opens.

Use this option only to change projection information that is incorrect due to importing or other errors. You must use the regular rectification procedures to georeference an ungeoreferenced file.

You must first remove any existing map projection information by selecting Edit > Delete Projection from Image Metadata menu bar. Then you must add the new projection information to Map Info record with Edit > Add/Change Projection

Delete Projection -Remove projection information.

Add/Change Elevation Info -Modify the elevation information associated with this file. The Elevation Info Chooser dialog opens.

Remove Elevation Info -Remove the Elevation Information from the file. This option is enabled if the file has elevation information associated with it.

Recalculate Elevation Values -Recalculate the elevation values in the image. The Recalculate Elevation for Images dialog opens. This option is only available if the current file had Elevation Information associated with it.

Add History CommentAdd a comment to the image history. This option is available only if the image already contains a history or if the Save File History preference is selected in the Image Files (General) category of Preference Editor. The Add Comment dialog opens.

Remove History - Remove the entire image history. This option is available only when an image history exists. A warning is given before the history is deleted.

Raster Attribute Editor -Modify raster attributes. The Raster Attribute Editor dialog opens.

View - Open the View options menu. The keyboard shortcut is Alt+V.

Histogram  View or print a histogram. The Histogram dialog opens. The keyboard shortcut is Ctrl+H.

Pixels - View pixel data. The Pixel Data dialog opens, showing all the data file values for the current layer.

Help

Help for Image Metadata - Open this Help document.

Toolbar

open.png  - Open a file to review the metadata. This is the same as selecting File > Open from the menu bar. The File Selector opens. The keyboard shortcut is Ctrl+O.

new - Open a new Image Metadata dialog. This is the same as selecting File > New from the menu bar. The keyboard shortcut is Ctrl+N.

print - Print information to the selected printer. This is the same as selecting File > Print from the menu bar. The keyboard shortcut is Ctrl+P.

stats - Create reduced subsampled raster layers, and compute statistics on specific regions or layers of the image file. This is the same as selecting Edit > Compute Pyramid Layers/Statistics from the menu bar. The Pyramid Layer/Statistics Generation Options dialog opens.

optimize_pyramid - Transform legacy metadata about image pyramids into a more optimized form for display. This command should be run on any legacy dataset that has pyramid layers available. New pyramids generated will already be in optimized form.

SHARED Tip This option is disabled when the image pyramid metadata is already in optimized form, or when the image does not have pyramids available.

hist - Display the histogram of the current layer. This is the same as selecting View > Histogram from the menu bar. The Histogram dialog opens. The keyboard shortcut is Ctrl+H.

[current layer number] Number of the current layer. Change the value in this field to view another layer.

[current layer name] Name of the current layer. Click the arrow to see all of the available layers or to view another layer.

allup - Move up one layer in all active Image Metadata dialogs.

alldown - Move down one layer in all active Image Metadata dialogs.

Image Metadata Tabs

To scroll to each tab, press Ctrl+Tab on your keyboard as a shortcut.

General

The General tab contains information such as layer name and size, layer pixel information, statistics, file or map coordinates, and general map projection information.

File Info Shows basic information about the entire file. The file name displays in parentheses next to the dialog title.

File Path     Shows the location of the file on disk. If the path is long, drag the dialog to enlarge it to see the entire path.

Layer Name Shows the name of the currently selected layer.

Last Modified Shows the last modification date for the layer.

Image/Auxiliary File(s)    Shows a list of all image and auxiliary (.aux) file(s) in the complete geospatial image.

File Type     Shows the file type of the selected layer. For example, IMAGINE Image, TIFF, DTED, NITF.

Number of Layers Shows the total number of layers in this file.

File Size     Shows the file size in bytes of the image including all auxiliary files.

Layer Info Shows information about the current layer.

SHARED Tip Indicates the size of the block fetched from the disk, but there may be instances where this is not the block size on the disk.The tile length and width may not always be the same as the block width.

Width Shows the width (X dimension) of the layer in pixels.

Height Shows the height (Y dimension) of the layer in pixels.

Type Shows the layer type as either Thematic or Continuous. The layer type can be changed by selecting Edit \-> Change Layer Type in the menu bar.

Block Width Shows the block width of the selected layer. The block size (pyramid layer) can affect processing and display time. The ERDAS IMAGINE default block width is 512 pixels.

Block Height Shows the block height of the selected layer. The block size (pyramid layer) can affect processing and display time. The ERDAS IMAGINE default block height is 512 pixels.

Data Type Shows the data type of the selected layer. The raster data type determines the range and precision of the file values in the raster layer.

Compression Shows whether or not the layer is in compressed format. If the layer is compressed, the type of compression method used is shown. None indicates no compression.

Data Order Shows how the data is arranged within the selected layer. One of the following values is reported: BIL (Band Interleaved By Line), BIP (Band Interleaved By Pixel), BSQ (Band Sequential), BIK (Band Interleaved by Block) or TILED (Tiled or blocked image).

To enumerate all possible raster data orderings, you must first define five parameters:

C - Block column

Indicates the horizontal index of a block

R - Block row

Indicates the vertical index of a block

B - Band

If an image has more than one band, this indicates the band index

X - Sample column

This indicates the horizontal position of a sample within a block

Y - Sample row

This indicates the vertical position of a sample within a block

To define an ordering, the parameters are arranged in order based on their iteration order. The most quickly varying parameter (the innermost loop) is placed first. The iterations for each parameter occur between limits. One limit for each parameter is zero. The other limits are 1", respectively.

Each parameter can be iterated in incrementing or decrementing order. Incrementing is the most common, and therefore assumed unless a minus (-) sign follows the parameter.

Sample orderings

Non-tiled BIL

XBYCR

Generic Binary BIL

Non-tiled BIP

BXYCR

Generic Binary BIP

Non-tiled BSQ

XYCRB

Generic Binary BSQ

Non-tiled Inverted BSQ

X-Y-C-R-B

BSQ written from bottom right to top left

Tiled BSQ

XYBCR

Like IMAGINE .img

BIK

XYBCR

Band interleaved by Block format means data will be written XYBCR. For example, if an application specifies this order along with a 64X64 block size, data would be written out for all layers of the first 64X64 block, then all layers of the next 64X64 block and so on.

DLLs will be able to report any of the orderings with an exclamation mark following the order. This will mean that data must be supplied to the DLL in that order when writing blocks. For example, BIK! means that the DLL is only able to write when blocks are given in that order and cannot handle blocks in arbitrary order.

SHARED Tip Compressed files that have been raster edited may not strictly adhere to the Data Order reported.

Pyramid Layer Algorithm Shows the algorithm (IMAGINE, ErdasBino3, and so forth) and the kernel (2 x 2, 3 x 3, 4 x 4) used to calculate the pyramid layers, if they have been created. If the pyramid layers are absent, this field displays No pyramid layers present.

Statistics Info This group is based on statistics that are calculated from the file pixel values of the pixels in the layer. This information can be created or edited by selecting Edit > Compute Pyramid Layers/Statistics in the menu bar.

SHARED Tip For multispectral data, the View generates Quick Statistics only for the layer or layers it is displaying. When you open Image Metadata, it defaults to showing you the info for layer 1. If you did not choose to display layer 1, then there are no stats for layer 1. If you change the layer in Image Metadata to show the info for one of the bands you have displayed, then stats for that layer also show.

Min Reports the minimum (lowest) file value.

Max Reports the maximum (highest) file value.

Mean Reports the mean (average) file value.

Median Reports the median of the file values (point at which there are as many pixels greater as lesser).

Mode Reports the mode (most frequently occurring) among the file values.

Std. Dev Reports the standard deviation, a statistical indication of the spread of the data.

Skip Factor X Reports the skip factor in the X direction of the image used to compute the statistics.

Skip Factor Y Reports the skip factor in the Y direction of the image used to compute the statistics.

The Skip Factor indicates how many pixels were skipped in the image in the X and Y direction during computation. A lower skip factor means greater statistical accuracy, while a higher skip factor means faster computation time.

Skip factor 1    every pixel is sampled

Skip factor 2    every other pixel is sampled

Skip factor 3    every third pixel is sampled

Last Modified Shows the date and time that statistics were last rebuilt.

Statistics Values Notes

There are cases in which one or more of the following statistics values may be present:

-1.#INF -- negative infinity minimum value

1.#INF -- positive infinity maximum value

1.#QNAN -- Not a Number

The infinity values may occur when the finite limits of floating point arithmetic have exceeded the data type in which the data are stored, or when the operation does not make mathematical sense, such as divide by zero. The Not a Number value can sometimes occur when an operation does not make mathematical sense, such as divide by zero.

To avoid -1.#INF or 1.#INF in statistics, define the data type as floating point double precision. This method works in most cases.

SHARED Tip When the statistics for a displayed image were generated from Quick Statistics, the Skip Factor X and Skip Factor Y values each report as 999.

Map Info Shows information about the map system associated with a layer. The way this information is viewed is based on the status of the checkbox.

File If the checkbox is not checked, ULX, ULY represents the map coordinates of layer pixel 0, 0. LRX, LRY represents the map coordinates of layer pixel W-1, H-1, where W and H are the width and height of the layer (in pixels) respectively. If the image layer has been rectified with its associated map system, the pixel size X, Y represents the width and height of a layer pixel in map units. If the image layer has not been rectified with its associated map system, the pixel size X, Y is not applicable.

View If the checkbox is checked, ULX, ULY and LRX, LRY define the map coordinates of the upper-left and lower-right pixels of the entire image layer viewed in its map system (rectified). The pixel size X, Y are determined by first finding the map bounding box of the image in its map space and then computing a pixel size that would allow the image layer to be viewed in map space by using the same number of pixels that are in the original image layer. Once the pixel size is determined, the upper-left and lower-right corners of the map bounding box are offset by one half of a pixel in both coordinate dimensions to compute the ULX, ULY, LRX and LRY values. All of this information is used by the Viewer to display the image when Orient Image to Map System checkbox in Raster Options tab of File Selector is selected.

For rectified image layers, the File and View information is identical. For image layers that are not associated with any geographic map system, a pixel map system is used so that IMAGINE applications can always deal in map units. In these cases, the File and View information are identical except that the pixel size is not applicable to the File information as an indication that a pixel map system has been constructed as a default.

Even if the fields are disabled, you can change this information once you select a map projection. Select Edit > Change Map Model from the menu bar.

Upper Left X Shows the X map coordinate of the center of the upper-left pixel in the file.

Upper Left Y Shows the Y map coordinate of the center of the upper-left pixel in the file.

Lower Right X Shows the X map coordinate of the center of the lower-right pixel in the file.

Lower Right Y Shows the Y map coordinate of the center of the lower-right pixel in the file.

Map Coordinate Origins

Various image data formats use the Upper Left (UL) pixel center or Upper Left pixel upper-left corner as the map coordinate origin, and the respective origin locations are reported on the respective Image Metadata tabs. The coordinates reported on General tab use the UL pixel center as the origin, or IMAGINE calculates the UL pixel center using the upper-left corner of the UL pixel.

Referencing UL pixel center as the map coordinate origin is known as pixel is point. Some GeoTIFF data reference UL pixel upper-left corner as the map coordinate origin, known as pixel is area. When encountering any image data using UL pixel upper-left corner, IMAGINE calculates the coordinate shift and reports the map coordinate as the UL pixel center. There is no change to the GeoTIFF tags.

Format .img uses the UL pixel center as the origin.

Format .tif can be either UL pixel center or UL pixel upper-left corner as origin.

Pixel Size X Shows the geographical area, in map units, represented by each pixel in the X (horizontal) direction.

Pixel Size Y Shows the geographical area, in map units, represented by each pixel in the Y (vertical) direction.

Unit Shows the map units used.

Geo. Model Indicates whether geocorrection has been applied to the file.

None    No geocorrection has been applied.

Map Info    Image has been geocorrected.

Affine    Affine geometric model has been applied.

RFunctions    Geocorrected with a model requiring Rational Polynomial Coefficients.

GOP    Geocorrected with Orbital Pushbroom model.

Projection Info Shows map projection used on the file. If the file is not georeferenced, then these fields are disabled.

Even if the fields are disabled, you can change this information once you select a map projection. Click Edit > Add/Change Projection from the menu bar.

Projection Shows the map projection and Zone number (if applicable) for this file.

Spheroid Shows the spheroid used.

Datum Shows the datum used.

EPSG Code     Shows the EPSG Coordinate System Geodetic Parameter Dataset numeric identifier for the map projection.

Projection

The Projection tab reports the map projection information if it is present in the image. The categories displayed are dependent on the Projection Type and the information stored in the metadata.

Projection Type     Shows the name of the map projection for this file.

Spheroid Name     Shows the name of the spheroid used.

Spheroid Axis     Shows the length in meters of the semi-major axis and semi-minor axis of the spheroid used.

Datum Name     Shows the name of the datum used.

Datum Grid     Shows the name of the datum grid shift file if used, which contains parameters to transform coordinates from one datum to another.

Datum Parameters     Shows the datum parameters, if a parametric datum is used.

Scale factor at central meridian     Modifies the scale distortion. A value of one indicates true scale only along the central meridian. A factor of less than, but close to one is often used.

Longitude of central meridian     Defines the degrees of longitude of the central meridian.

Latitude of origin of projection     Defines the line of latitude (parallel) of the origin of the map projection.

False easting     A value applied to the easting coordinate to prevent negative values when moving west from the central meridian. Easting coordinate for a feature is the distance in meters east or west of the central meridian.

False northing     A value applied to the northing coordinate to prevent negative values when moving south from the latitude of origin. Northing coordinate for a feature is the distance in meters north or south of the latitude of origin.

Latitude of 1st standard parallel     First line of latitude (parallel) used as control lines in the computation of a map projection. The first standard parallel is the southernmost.

Latitude of 2nd standard parallel     Second line of latitude (parallel) used as control lines in the computation of a map projection, used with a first standard parallel.

UTM Zone     If the Projection Type is UTM, shows the UTM Zone number.

NORTH or SOUTH     If the Projection Type is UTM, shows whether the projection is North or South.

State Plane Zone     If the Projection Type is State Plane, shows the State Plane Zone number.

Zone Type     If the Projection Type is State Plane, shows the zone type.

NAD     If the Projection Type is State Plane and uses a North American Datum, specifies which datum is used.

Projection Detail     If UTM or State Plane is used, shows the name of the map projection used since these systems are plane coordinate systems.

Several of the Projection Type parameters listed above may be displayed in this section.

Histogram

The Histogram tab shows the image histogram without the need to open a second dialog.

See Histogram Frame Part Help topic for descriptions of the histogram graphics and reported values.

[histogram graphic]    Displays a histogram graphic of the current layer.

Bin Function Reports the type of bin function used in the current layer. Bins are used to group ranges of data values together in a descriptor table for better manageability. The bin function establishes the relationship between data values and rows in the descriptor table.

Print    Click to print this histogram on a printer device.

Pixel data

The Pixel data tab contains a CellArray showing the data file values of each pixel for the current data band.

For raster files, the data value is a digital number (DN).

Specifically, for a continuous image, the DN is the brightness value.

For a thematic file, DN is a digital number.

For a DEM image, DN is an elevation value. If the elevation info is defined, the unit of measure is specified in Elevation Info tab > Elevation Units. If the elevation info is not defined, the value is still a digital number depicting the elevation of the file, however the specific height unit is unknown.

For more information, see Image Data in the Producer Field Guide.

File History

The File History tab contains user comments describing changes to the image.

saveClick to write the history to a text (.txt) file. The File Selector dialog opens.

search    Click to find a word or phrase in the image history. The Find dialog opens.

finddestClick to find the next occurrence of the search string in the image history.

Elevation Info

The Elevation Info tab contains the elevation information for the image. To create or edit Elevation Information, click Edit > Add/Change Elevation Info.

Spheroid Name    Shows the spheroid used to calculate the elevation.

Datum Name Shows the datum on which the elevation is based.

Elevation Units Shows the units used to measure the elevation.

Elevation Type Shows how the elevation values are measured.

Height Elevation values of points above the Vertical Datum Surface are positive, while the elevation values of points below the Vertical Datum Surface are negative.

Depth Elevation values of points below the Vertical Datum Surface are positive, while the elevation values of points above the Vertical Datum Surface are negative.

SHARED Tip Depth measurement is used only with underwater measurements.

NITF Info

The NITF Info tab reports the values, long names of NITF tags associated with a NITF file.

Component Panel

The Component panel shows folders identifying each of the different components of the current NITF file, such as Main Header and individual Images.

Click a component to display the tags and associated values in the CellArray.

CellArray

Field    Reports the tag name.

Value    Reports the value of the respective tag.

GCPTable

The GCP Table tab reports that ground control points are collected from a TIFF or .img file if the GCPs are stored in the header.

ECW or JP2 Info

For ECW images, the ECW tab reports values of ECW tags associated with an ECW file. For JPEG2000 images, the JP2 tab reports values of JPEG2000 tags associated with a JPEG2000 file.

ECW v3 format stores statistics and histograms directly in the ECW file. ECW v2 format stores statistics and histograms in the AUX file. The Skip Factor used for calculating statistics is not stored in the ECW v3 file format. The Edit option in Image Metadata dialog and Edit Image Metadata dialog store statistics in the ECW v3 file when the image is not displayed in the Viewer.

SHARED Tip When the image is displayed in the Viewer, the image is locked and the statistics will not be stored. Clear the Viewer first to allow the statistics to be stored.

Many of these tags are also shown on the General tab.

Table 1:ECW or JP2 Tag Name Descriptors

ECW or JP2 Tag Name

Value

Raster X Dimension

Number of columns of pixels in the layer, that is, the number of pixels per row. Same as Width in General tab > Layer Info section.

Raster Y Dimension

Number of rows of pixels in the layer. Same as Height in Layer Info section.

Band(s)

Number of bands (layers) in the image. Same as Number of Layers in File Info section.

Opacity Layer

Yes - an opacity layer (Alpha channel or opacity mask) exists in the file.

No - an opacity layer does not exist in the file

Cell Size Unit

Unit of measure of the cell (pixel)

Cell Type

Raster data type of the cell (pixel). Same as Data Type in Layer Info section.

Pixel Origin X

X map coordinate of the center of the upper-left pixel in the file. Same as Upper Left X in Map Info (see above) section.

Pixel Origin Y

Y map coordinate of the center of the upper-left pixel in the file. Same as Upper Left Y in Map Info section.

Rotation Degree

Clockwise rotation of the image in world coordinate space, expressed in degrees.

Datum

Datum used. Same as Datum in Projection Info section.

Projection Name

Map projection used. Same as Projection in Projection Info section.

EPSG Code

EPSG Coordinate System Geodetic Parameter Dataset numeric identifier for the map projection. Same as EPSG Code in Projection Info section.

Target Ratio

Target Compression Ratio -- For ecw files, a value is shown. For example, value of 20 indicates ratio 20:1.

Standard jp2 does not have the ability to store the target ratio, therefore a value of 0 (zero) is shown indicating ratio is unknown.

Actual Ratio

This is not a field that is read from or stored in a tag – it is one that is calculated from data file values. The formula used is:

(((Rows x Columns x Bands x Bit-depth / 8) / 1024^2) / Encoded image size in MB)

Block Width

Number of pixels per block in width of file

Block Height

Number of pixel per block in height of file

Compress Format

Type of color space, that is, model describing the way colors are represented.

None

Greyscale

YUV

RGB

Multiband

sRGB

YCbCr

ECW Version

Version of ECW compression, value is 2 or 3

Contains RPC

Specifies whether or not RPC (Rational Polynomial Coefficients or Rapid Positioning Capability) data are stored. RPC information involves various parameters (such as error, offset, scale and the coefficients) which are required to reconstruct an approximate transformation matrix.

Contains Statistics

Specifies whether or not statistics data are stored.

Contains Histogram

Specifies whether or not histograms are stored.

Company Name

Name of company that compressed the data.

Software Name

Name of software that compressed the data.

In addition to the above mentioned tags, JP2 Info tab displays GeoTIFF Key Tags associated with JP2 file. For more information on GeoTIFF Key Tags see Table 3 below.

JP2_GML

The JP2_GML tab reports the values of XML data stored in the JPEG 2000 data file. Geography Markup Language (GML) is a set of XML schemas for encoding geographic information including geographic features, coverages, observations, topology, geometry, coordinate reference systems, units of measure, time, and value objects.

JPEG 2000 is a wavelet based encoding for imagery that provides the ability to include XML data for description of the image within the JPEG 2000 data file.

For more information, visit the Open Geospatial Consortium web site at http://www.opengeospatial.org/standards/gmljp2.

TIFF Info or BigTIFF Info

The TIFF tab reports the values of the TIFF Tags and GeoTIFF Key Tags associated with a TIFF file or BigTIFF file.

Image    Double-click the folder or click + to expand the tree view to display the TIFF tags and GeoTIFF folders.

TIFF Tags    Click the folder to display each TIFF Tag name and respective value. See Table 2 below.

GeoTIFF Keys    Click the folder to display each GeoTIFF Key Tag name and respective value. See Table 3 below.

Tag    Tag name

Data Type    Raster data type notated in TIFF specification format

Count    Number of instances of the value

Value    Value or description of tag name

INTERGRAPH Packet    Click the folder to display each private Intergraph packet name and respective value. See Table 4.

Table 2: TIFF Tag Name Descriptors

TIFF Tag Name

Value

SubfileType (deprecated)

NewSubfileType

Type of data contained in this subfile.

0 = full resolution

1 = reduced resolution version of another image in this TIFF file, or single page of multi-page image, or transparency mask for another image in this TIFF file (PhotometricInterpretation value must be Transparency Mask).

ImageWidth

Number of columns of pixels in the image, that is, the number of pixels per row.

ImageLength

Number of rows of pixels in the image.

BitsPerSample

Number of bits per component. Most RGB color data will have the same number for each of the three components.

Compression

Compression scheme used.

PhotometricInterpretation

Color space of the image data.

RGB means red, green, blue.

Min Value is Black means the minimum value is imaged as black.

Palette color means a color is described with a single component.

Transparency Mask means the image is used to define an irregularly shaped region of another image in the same TIFF file.

StripOffsets

For each strip, the byte offset of that strip.

Orientation

Orientation of the image with respect to the rows and columns.

SamplesPerPixel

Number of components per pixel.

RowsPerStrip

Number of rows per strip. RowsPerStrip + ImageLength = number of strips in entire image.

StripByteCounts

For each strip, the number of bytes in the strip after compression.

XResolution

Number of pixels per resolution unit in the ImageWidth direction.

YResolution

Number of pixels per resolution unit in the ImageLength direction.

PlanarConfiguration

How the components of each pixel are stored.

ResolutionUnit

Unit of measurement for XResolution and YResolution. Value can be none, inch, centimeter.

Software

Name of software package used to create the image.

TileWidth

Tile width in pixels; number of columns in each tile. Must be multiple of 16 to be compatible with compression schemes such as JPG.

TileLength

Tile length in pixels; number of rows in each tile. Must be multiple of 16 to be compatible with compression schemes such as JPG.

TileOffsets

For each tile, the byte offset of that tile, as compressed and stored on disk. The offset is specified with respect to the beginning of the TIFF file. Offsets are ordered left-to-right and top-to-bottom.

TileByteCounts

For each tile, the number of (compressed) bytes in that tile.

ExtraSamples

When SamplesPerPixel value is greater than PhotometricInterpretation value, then this field describes the meaning of the extra samples, typically for non-color information such as opacity.

SampleFormat

How to interpret each data sample in a pixel.

1 = unsigned integer data

2 = two’s complement signed integer data

3 = IEEE floating point data

4 = undefined data format

GeoPixelScale

Indicates the size of raster pixel scaling in the model space units. Consists of ScaleX, ScaleY, ScaleZ where ScaleX and ScaleY give the horizontal and vertical spacing of raster pixels. ScaleZ maps the pixel value of a DEM into the Z-scale.

GeoTiePoints

Indicates raster-to-model tiepoints in the order (...I,J,K, X,Y,Z...) where I and J are locations in raster space with pixel-value K, and X,Y,Z is a vector in model space.

Table 3: GeoTIFF Key Name Descriptors

GeoTIFF Key Name

Value

GTModelTypeGeoKey

Type of Model Coordinate system used:

Projected = Projection Coordinate System

Geographic = Geographic lat-lon System

Geocentric = Geocentric (X,Y,Z) Coordinate System

GTRasterTypeGeoKey

Raster Space coordinate system used: Raster pixel is area, Raster pixel is point, or undefined

GTCitationGeoKey

Gives an ASCII reference to published documentation on this file’s configuration.

ProjectedCSTypeGeoKey

Names the Projected Coordinate System.

PCSCitationGeoKey

Gives an ASCII reference to published documentation on the Projected Coordinate System.

ProjLinearUnitsGeoKey

Definition of linear units used by this projection.

Table 4: Intergraph Packet Descriptors

Intergraph Packet

Value

Acquisition info

ID -- 1 = gray, 2 = red, 3 = green, 4 = blue, 5 = infrared, 5 = near IR, 8 = lum, 9 = YIQ blend ratio for NTSC luminance, 10 = HSL gray lightness;

pad_to_dword;

version;

camera serial number;

Camera name;

frame ID -- image product ID such as RPAN, RMS2, RMS3;

focal length in millimeters;

sensor resolution in nanometers;

time zone;

date;

seconds-of-week on GPS clock;

unitless GSD sensor resolution;

exposure count, or shutter click count;

flight ID, batch of exposure such as a roll number

Histogram

ID -- There may be up to 3 copies of histogram packets; each should have different ID numbers;

char pad;

unsigned integer count -- always 256 in length for 8 bit data or 3 bands of 8 bit data. Otherwise, length corresponds to information held in the pixel bits packet.

For 8 bit data; length = 256

For 9 bit data; length = 512

For 10 bit data; length = 1024

For 11 bit data; length = 2048

For 12 bit data; length = 4096

not used for greater than 12 bit data

Pixel bits

Number of significant bits within pixel;

Signed or Unsigned; 0 = unsigned, 1 = signed

Advanced overview

kernel type -- 0 = subsampling is considered odd - no kernel necessary

1 = for single-bit images only - no kernel necessary

2 = 2x2 averaging

3 = 5x5 Gaussian

4 = 8x8 Kodak ICA approximation

6 = 8x8, 4x4, or 2x2 DCT averaging for .jpg files;

kernel dim - we require a square kernel;

double divisor;

char description;

double coefficients -- "kernel_dim" x "kernel_dim" array of doubles. These values must sum to equal the divisor. Row-major order.

Intergraph Flag Registers

Intergraph Application specific registers. Each of the 16 registers is a 32-bit integer. The bottom two bits of the first register are assigned as:

0 = overview (if any) was created by subsampling

1 = overview (if any) was created by an XOR process

2 = overview (if any) was created by averaging

3 = overview (if any) was created by 5x5 Gaussian kernel

Intergraph Advanced Overview Packet Notes

Note 1

Overview generation can be modeled as filtering the main image with the above kernel, and then subsampling the main image to create the overview. In practice, more efficient methods are used, but mathematically, the result is the same.

This means that the "hot spot" or "kernel center" value is the center of any odd kernel. However, for even kernels, we have four "center" coefficients. We define the upper-left, or lowest coordinate of the center 4 kernel values as the "center" for all kernels defined by this packet. This is coefficient (kernel_dim/2 -1 , kernel_dim/2 -1) for even kernel_dim and ( floor(kernel_dim/2) , floor(kernel_dim/2) ) for odd kernel_dim.

If this is not the behavior you want, you can make your kernel bigger and zero pad to put your particular "hot spot" in the center position as described above.

Note 2

Given the filtering model mentioned above, what is done at the image boundaries?

For current kernels, - averaging has no boundary issue, Gauss and DMC both reflect the image data out to provide support for the kernel extents. We will assume that all future kernels do the same.

More information about Intergraph's private TIFF tags can be found at http://www.awaresystems.be/imaging/tiff/tifftags/docs/intergraph.html

Sensor Name Header

Some sensors may supply the contents of the image header information that can be viewed on this tab.

For information about various file types, see File Specifications.