Options

Click on this button or the menu item to show the Options tabbed dialog box:



























Display Options:

In the left panel, you can choose the appearance of the output image. 

Choose Overlay Source + Target White if you have a black and white map and wish to display the black lines of the map in white where they correspond with features in the transformed image.

Choose Overlay Source + Target Black if you have a black and white map and wish to display the black lines of the map in black where they correspond with features in the transformed image.

Overwrite Target uses the input image (Source) to overwrite the output image (Target) after transformation regardless of the colour of the target.

Merge Source with Target places those parts of the input image in areas of the output image which are pure white, leaving the remainder of the output image untouched.

White and Black backgrounds create target images that show only the transformed data on the respective white or black backgrounds.

If you have chosen Mix as an output option, you can choose the percentage of mixture of the source and the target image after transformation with the trackbar next to the Mix button. 

Inserting means that if a source image pixel is not white, it is inserted into the target, otherwise the target is left as it is.

The Xor option gives false colour output which may be useful for testing the visibility of a transformation to an image background like an orthophoto. It is normally not used as a permanent result.
It is recommended to try various options followed by an Undo to see what they do to your data. This must be done without using the Transform and scale option which does not support undo, because it must close the original images before displaying them. 

Interpolation Options:

The transformation calculates the colour or gray value at the position of an output pixel from the input image. The interpolation option permits choosing the way the pixel value is computed from its nearest neighbours, since the transformed position usually falls inbetween four adjacent pixels. The speed of calculation for each output pixel depends on the choice of interpolation:


1) Coarse: the colour or gray value of the nearest neighbour to the computed input position is taken. This is the fastest method, but it may produce a jagged appearance in straight line features (aliasing).
2) Medium: the colour or gray value is interpolated bi-linearly dependent on the values of the four neighbours and the distance of the calculated point from them. This is nearly as fast as the nearest neighbour method, but it blurs the result slightly.
3) Fine: the colour or gray value is interpolated from the 16 nearest neighbours of the pixel using an aproximation to a sin(x)/x (sinc) function which best preserves fine detail. Since considerably more calculation is required, this is the slowest method.

Reprojection Warning:

If you don't want to be bothered by warnings when the reprojection error exceeds 1% of the average side lengths of all images, uncheck the Reprojection Warning box.

File Default Options:



























Here in the left panel, you can choose to display either all supported types of image files or only a single type which you select.  Similarly, you can choose the type of output file in the right panel.