For retinal fundus images, the align options are quite simple. Unlike other modalities, there are no layout options because the layout is dictated by the geometry of the retinal surface and by the optics of fundus cameras. The masking process is applied automatically to retinal images. Users who are working with different types of retinal images other than color, red-free and fluoresceins are encouraged to try "Other Modalities".
Aligned Images Crop Options
The Aligned Images Crop Options controls how the aligned retinal images are cropped individually before they are saved. There are three possibilities:
- If the user clicks None then no cropping is applied.
- If the user clicks Intersection then the images are cropped to their intersection. If the intersection is empty, then no cropping is applied.
- If the user clicks Target, then after the Align Images button is pressed to start the alignment process, a new window pops up for the user to choose one of the selected images as the "target". The alignment process then continues and after it is done, the aligned images are cropped, restricting them to the area of the (aligned) target image. Of course, the target image itself will not be cropped.
Aggressive Registration
Clicking this button tells i2k Retina to be more aggressive than usual in trying to align each pair of images. This allows it to handle tougher cases while taking a bit more computation time. On rare occasions this leads i2k Retina to make mistakes, so this should be used only when ordinary registration fails and when the user is certain the images should be aligned.