/*!

*

* OVERVIEW:

*

* this app is a simple image open.

* It should open any image supported by the ossim library.

* Once the image is open it prints out some general information

* about the image.

*

* PURPOSE:

*

* Learn how to open an image and query attributes. Also learn which

* headers are required to perform these tasks.

*

*/

// iostream is used for general output

//

#include <iostream>

// within this program ossimCommon is used for ossimGetScalarSizeInBytes.

// This header will have some common globabl inline and non-inline functions

//

#include "base/common/ossimCommon.h"

#include "base/data_types/ossimFilename.h"

// used to get the string name of the scalar type for the handler. The scalar

// type specifies if its unsigned char, float, double, ...etc

//

#include "base/misc/lookup_tables/ossimScalarTypeLut.h"

// This is the majic number factory. All loader are registered to this factory.

// it will lookp through all factories to try to open the passed in image file

//

#include "imaging/factory/ossimImageHandlerRegistry.h"

// Base pointer for the passed back object type

//

#include "imaging/formats/ossimImageHandler.h"

// this is the most important class and is called as the first line of all applications.

// without this alll the important factories are not created.

//

#include "init/ossimInit.h"

using namespace std;

int main(int argc, char* argv[])

{

ossimInit::instance()->initialize(argc, argv);

if(argc == 2)

{

// call the registries open and let it traverse through all registered

// factories to open up an image.

//

ossimImageHandler *handler = ossimImageHandlerRegistry::instance()->open(ossimFilename(argv[1]));

if(handler)

{

// includes full resolution so if there are no overviews this value should be

// 1. Note: resolution levels or overviews or indexed from 0 being full

// resolution to (number of decimations or overviews -1..

//

// Overviews are very import for resampling images to different resolutions efficiently.

// The overviews are generally power of 2 decimations. Assume we have an image that has

// full resolution of 1024x1024 in size. When we are talking about resolution 0 then

// we are talking about the full res 1024x1024, but when we are talking

// about resolution level 1 then we are looking at the start of the overview and referes to

// a decimation of 2^1 which is 512x512 image. So when we ask for resolution level N then

// we are talking about a decimation of 2^N

//

// So again, when we query the number of decimation levels this includes resolution layer 0.

//

int overviews = handler->getNumberOfDecimationLevels();

// the image bounds can take an argument to specify which resolution I would like to get

// the bounding rect of. By default if no argument is given it assumes full resolution or

// resolution 0.

//

ossimIrect bounds = handler->getBoundingRect(0);

// scalar type cooresponds to the pixel radiometry type. The pixel can be of precision

// float, double, unsigned char, unsigned short, signed short data values. Look at

// ossimScalarType enumeration found in base/common/ossimConstants.h for supporting types

//

ossimScalarType scalarType = handler->getOutputScalarType();

// This is a utility class that maps enumeration values to strings. So we will use this

// when we query the scalar type from the image and wish to print the text version of it.

//

//

ossimScalarTypeLut* lut = ossimScalarTypeLut::instance();

cout <<"filename = " << handler->getFilename() << endl

<< "width = " << bounds.width() << endl

<< "height = " << bounds.height() << endl

<< "overview count = " << (overviews-1) << endl

<< "scalar type = " << lut->getEntryString(handler->getOutputScalarType()) << endl

// ossimGetScalarSizeInBytes is a utility functions found in base/common/ossimCommon.h

// it will return the byte size of the scalar type.

//

<< "pixel size = " << ossimGetScalarSizeInBytes(scalarType) << " byte(s)" <<endl

<< "Handler used = " << handler->getClassName() << endl;

delete handler;

}

else

{

cout << "Unable to open image = " << argv[1] << endl;

}

}

else

{

cout << "usage: open_image <file name>" << endl;

}

// call the finalize so the ossim can cleanup if needed.

ossimInit::instance()->finalize();

return 0;

}