= img2rr = img2rr is a command line application used to create reduced resolution data sets for an image. These datasets are created by iteratively downsampling the full resolution image. The results are stored using a pyramid image structure called overviews. These overview files improve the efficiency of arbitrary access to different spatial resolutions and areas of interest. This is important if you want to zoom in and out of ossim applications like [wiki:OssimPlanet] or [wiki:ImageLinker] and are critical for rapid resizing using [wiki:orthoigen] and [wiki:igen]. Overview files created by img2rr use a ".ovr" extension. img2rr will also create a ".omd" file which contains basic radiometry information. Users also have the option to create histogram files when generating overviews. These files have a ".his" file extension. == Usage == {{{ img2rr [options] }}} == Options == {{{ --compression-quality Compression quality varies from 0 to 100, where 100 is best. Currently only for JPEG compression --compression-type Compression type can be: NONE, JPEG, PACKBITS, or DEFLATE --create-histogram Computes a histogram. --create-histogram-fast Computes a histogram in fast mode which samples partial tiles. --create-mask Computes a mask which applies to an image for cutting off black specks around the image. --disable-elev Will disable the elevation --disable-notify Takes an argument. Arguments are ALL, WARN, NOTICE, INFO, FATAL, DEBUG. If you want multiple disables then just do multiple --disable-notify on the command line. All argument are case insensitive. Default is all are enabled. --disable-plugin Will disable the plugin loader --histogram-bins Number of histogram bins. This will override the default for scalar type. Also this will force a separate pass. --histogram-max Maximum histogram value to use. This will override the default for scalar type. Also this will force a separate pass. --histogram-min Minimum histogram value to use. This will override the default for scalar type. Also this will force a separate pass. --histogram-r0 Forces create-histogram code to compute a histogram using r0. If source image has reduced resolution sets built in a separate pass will be made at r0. --list-entries Lists the entries within the image --ossim-logfile takes a logfile as an argument. All output messages are redirected to the specified log file. By default there is no log file and all messages are enabled. --tile-size Defines the tile size for the supported overview handler. --version Outputs version information. --writer-prop Adds a property to send to the writer. format is name=value -K specify individual keywords to add to the preferences keyword list: name=value -P specify a preference file to load -T specify the classes to trace, ex: ossimInit|ossimImage.* will trace ossimInit and all ossimImage classes -V or --version Display version information. -a or --include-fullres Wants to include full res dataset as well as reduced res sets. -d Write overview to directory specified. -e or --entry Give the entry(zero based) to build an overview for. -h or --help Shows help -o Write overview to file specified. If used on a multi-entry file, given "foo.ovr" you will get: "foo_e0.ovr" -r or --rebuild Rebuild overviews even if they are already present. -s Stop dimension for overviews. This controls how many layers will be built. If set to 64 then the builder will stop when height and width for current level are less than or equal to 64. Note a default can be set in the ossim preferences file, setting the keyword "overview_stop_dimension". -t or --type see list at bottom for valid types. (default = ossim_tiff_box) }}} == Overview Types == img2rr provides users the option to specify file format for the output overviews via the -t argument. Valid overview types include: * ossim_tiff_box* * ossim_tiff_nearest * gdal_tiff_nearest * gdal_tiff_average * gdal_hfa_nearest * gdal_hfa_average * ossim_kakadu_nitf_j2k ''* default'' == Compression Options == By default, overviews are uncompressed TIFF files. However, there are several options available to create compressed overviews. * '''JPEG compression''' With ossim_tiff_box and ossim_tiff_nearest, you can create JPEG compressed overviews by setting "--compression-type JPEG". You can also specify the compression quality using the "--compression-quality" argument. Example: {{{ ossim-img2rr --compression-type JPEG --compression-quality 90 image.tif }}} When using JPEG compression, null areas are replaced with black pixels (RGB 0,0,0). To retain the null pixels, you must create a mask file. Example: {{{ ossim-img2rr --compression-type JPEG --compression-quality 75 --create-mask image.tif }}} * '''JPEG 2000 compression''' With ossim_kakadu_nitf_j2k, users have the option to create JPEG 2000 compressed NITF files. This option requires the [wiki:kakaduplugin Kakadu Plugin]. {{{ ossim-img2rr -t ossim_kakadu_nitf_j2k --writer-prop threads=4 --writer-prop compression_quality=visually_lossless image.tif }}} * '''ERDAS Imagine compression''' With gdal_hfa_nearest and gdal_hfa_average, users have the option to create overviews in ERDAS Imagine format. This option requires the [wiki:gdalplugin GDAL Plugin]. {{{ ossim-img2rr -t gdal_hfa_nearest image.tif }}} == Stop Dimension == Users can control how many layers will be create by specifying a stop dimension. The stop dimension is set using the -s argument. For example, stop building overviews when both width and height are less than or equal to 64: {{{ ossim-img2rr -s 64 }}} Build overviews, specifying to stop when both width and height are less than or equal to 1: {{{ ossim-img2rr -s 1 }}} Note a default can be set in the [wiki:ossimPreferenceFile OSSIM Preference File], setting the keyword "overview_stop_dimension". == Histogram Operations == img2rr provides an option to create a histogram when generating overviews. * '''create-histogram''' Computes a histogram. * '''create-histogram-fast''' Fast histogram computation When creating histograms, users have the following histogram options: * '''histogram-bins''' Number of histogram bins. * '''histogram-max''' Maximum histogram value to use. * '''histogram-min''' Minimum histogram value to use. == Examples == {{{ ossim-img2rr -t ossim_kakadu_nitf_j2k --create-histogram-fast --histogram-r0 --entry 2 data\cadrg\cdrgxGNCJNCN_10\RPF\a.toc }}} Build overviews, default type = ossim_tiff_box:[[BR]] {{{ ossim-img2rr }}} Build overviews forcing a rebuild if already present with -r option: {{{ ossim-img2rr -r }}} Build overviews specifying the output file with -o option: {{{ ossim-img2rr -o foo.ovr }}} Build overviews specifying the output directory with -d option: {{{ ossim-img2rr -d /tmp }}} Build overviews specifying the output directory with -d option and the output file with -o option. Good for multi entry: {{{ ossim-img2rr -d /tmp -o rpf-1 }}} Build overviews specifying the type: {{{ ossim-img2rr -t ossim_tiff_box }}} Build overviews copy r0 (full res layer) (ossim_tiff types only) {{{ ossim-img2rr -a }}}