An image is a graphic that contains a series of small squares, or pixels, to represent objects in a file. You cannot edit the individual elements of an image, such as reshaping a line, changing the colors of a line, or changing the line style.


Image Properties

Image object properties can be modified through the Property Manager. Image object properties are discussed Image Item Properties.


Georeferenced Images

Typically, images consist of pixel coordinates, the number of pixels in the X direction and the number of pixels in the Y direction. A georeferenced image contains real world coordinates, such as latitude, longitude or UTM, rather than pixel coordinates. Some images can have coordinate, projection, and datum information embedded in them (GeoTIFF) and some images have associated files that contains georeferencing information (Golden Software Reference .GSR, Blue Marble .RSF, ESRI .PRJ, and ESRI World File .TFW).


Georeferenced Images in Didger Projects

A georeferenced image contains a set of control points or transformation parameters that define the mapping from pixel coordinate space to the real world coordinate space.


If you import an image into a Didger project, you can also import vector files, data files, and other images into the plot window and overlay them. The projection information of an image can be changed once you import it into a Didger project.


Rectified Georeferenced Images

A georeferenced image can also be rectified in a Didger project. In most cases calibrating an image will not fully rectify it. If the georeferencing information contains any sort of warped component, rotation, or non-linear scaling along the axes, Didger has the tools to adjust an image by first calibrating and then by warping the image. Both processes are needed to most accurately rectify an image.


Images with Unknown Georeferencing

If you scanned an image, if you are unsure if the image is georeferenced, or if you know the image does not contain georeferencing, you can either import the image un-referenced into a project, let Didger define a set of coordinates for you, or you can georeference the image in the Image Registration and Warping dialog.


Image Scaling

Because image files are raster based, they cannot be scaled in the receiving application without distortion or some loss of resolution. They can be useful for reproducing the project image in other applications. If you need to reproduce and rescale the project image in another application, you might consider vectorizing the image or digitizing the image. The digitized information can then be exported to a vector format.



See Also




File Format Features

Object Types

Vectorize Image