Description:This dialog is used to calculate a probability distribution (PDF) of the image data. This PDF does not take spatial distribution into considiration. Once the PDF is created it can be stored in a database, or used to generate synthetic images.
We provide a tool that allows the user to create synthetic images based from probability distribution functions that have been previously captured from other images. This dialog consists of three seperate parts, the extraction, the database and the generation.
Extraction: The first part is for the user to extract the PDF from existing images. The user first selects which distribution to use (Johnson is a good choice, Various will try to use the best PDF possible, but if none is found it will default to a generic PDF that is based on the histogramed data (this is often the case)). Next the user selects if the image should be decorrelated using the PCA algorhtim and if there is any value in the mask that is considered background information and should be ignored. If the user selects the "Use invis mask?" option a value needs to be put in the field following it. To allow us during the generation phase to create images of any type and magnitude we scale the output of the PDF to values between 0 and 1, the following two fields allow the user to specify the min and max values. Next the user needs to specify what the azimuth and elevation are for when the image was taken. Clicking on "Add Database" will present the user with a dialog to load the image and with a dialog to load the mask. After this the PDF's for each of the band and mask regions will be extracted (after the optional PCA conversion) and stored the database.
Database: The database contains all the PDF's extracted for each mask type and band. The information in the database can be shown using the "Show Database" button, saved to disk using the "Save Database" button or loaded from disk using the "Load Database" button. The database is stored as serialized object on disk.
Generation: The final part of the dialog allows users to create images based on the PDF's stored in the database. First the user needs to select what angle the synthetic image will be generated from using the azimuth and elevation angles. Next the type and magnitude of the synthetic image needs to be set using the "Image Type" dropdown and the "Multiplier" field. Finally the user needs to specify how many bands the resulting image should have. When the user clicks on "Generate Image" a dialog will appear asking the user for a mask. The application will now go to the database and find the PDF's for each band and mask values and the specified angles (this combination should have been put into the database beforehand). After the image is generated and what the user expects, it can be saved to disk using the "Save Image" button.
When creating the database it is best to use a unique id for each clutter type, i.e. use 1 for black sand and 2 for white sand. Later when generating a synthetic image you can draw a mask with the clutter types you are interested in placing. So one can now draw a mask of a circle of white sand inside black sand, hit generate and create an image that was previously not captured.