FT on Full Image

Use the Image > Calculate Fourier Transform > FT on Full Image command to create a Fourier transformed image from the active image and to display it in the image window. Alternatively, in the Fourier Transform tool window, click the FT on Full Image button.

Prerequisite: This command is only available when the active document is a gray-value image. The command is shown in gray if the active image is an FT image, for example.

Creating an FT image from the live-image

You can also create FT images from the live-image. You can use this option to help you focus, for example.

What does the link between images and FT images mean?

After the calculation of the Fourier transform, the FT image stays linked to the source image until you remove the link. This link has the following consequences in your software.

•As long as the FT image is linked to the source image, you will find both images in the document area of the Fourier Transform tool window.

•On the source image, the image segment belonging to the FT image is displayed. As long as the FT image is linked to the source image, you can change the image segment. You can change it's size or move the entire image segment to a different part of the source image. The linked FT image is then updated accordingly, which means that the Fourier transform is re-calculated.

•As long as the FT image is linked to the source image, it's header in your software's document group is displayed in color. The color field in front of the FT image in the Fourier Transform tool window and the rectangle which shows the image segment in the source image used for the Fourier transform have the same color. This way, you can easily recognize which FT images correspond to which image segments when several FT images are defined on one source image.

Creating FT Images

1.Use the View > Tool Windows > Fourier Transform command to make the Fourier Transform tool window appear.

2.Load or acquire an image from which you want to create the Fourier transform.

•All of the following steps also apply to the live-image. To calculate the FT in the live-image, first switch to the live-image. To do so, use the Acquire > Live command.

3.Use the Image > Calculate Fourier Transform > FT on Full Image command.

•The FT image is computed from the source image.

•A new image window for the FT image is automatically created. This image window is displayed in its own document group to the right of the source image. This means that you can view the FT image and the source image at the same time.

•The FT image is given the default name FT <consecutive number> of <source image name>. The FT image's name is displayed in the Fourier Transform tool window and in the FT image's document title.

Note: If the FT image isn't automatically arranged to the right of the source image, you may be in the document group's single frame view. In this case, switch back to the tile view. You can find more information on this topic here.

•The image and the FT image are displayed in the Fourier Transform tool window.

Setting up a user interface for working with FT images

4.You can create as many document groups as you like in your software and arrange them in different ways. In this way, you can view the source image and two FT images at the same time, for example.

•You will find more information on arranging document groups here.

Saving FT images

5.In the document group, select the FT image that you want to save. FT images are identified by this icon in the document title.

6.Select the File > Save As... command to save the FT image. Always use the TIF or VSI file format when saving an image. Only then is the file type maintained.

•When saving the image, you are saving only the FT image. The source image or other FT images that may have been defined on the source image will not be saved.

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