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IntroductionSignal Manipulation > Dynamic Filtering > Image Filters
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Image Filters

Image filters are used as grey level visual filters superimposed on a spectrum to modify the amplitudes of its components.

Adding Image Filters to a Sound

  • Execute a sonogram analysis : select Analysis/Sonogram Analysis or press Cmd + D.

  • Possibly select a time region in the waveform window.

  • Select Treatments/Add Image Filter.

  • In the Select Image File dialogue window, select a location and an image file.

Image File Formats

AS accepts black and white or colour formats supported by QuickTime : jpg, .pict, .tiff or .pdf.


The image will be superimposed in black and white to the sonogram.

  • The image will fit the sonogram window. If a temporal selection has been done, it will be applied to this time selection, like any treatment. Consequently, its proportions may not be preserved.

  • An Image Filter block will appear in the Processing Sequencer.

  • The Inspector will display an Image Filter label, file informations, and the following parametric values :

    • Start, End, Duration

    • Low and High Frequency limits

    • Lower and Upper Threshold – contrast–

    • a Use Image Boundaries option

    • a Filter Mode menu

Image Size and Location

Image Size

An image can be resized laterally and vertically, on each side. Hover the pointer over a border to display a double triangle , then proceed with a click and drag.

If you wish to resize the image from its upper border, remember that when the image is added in the window, its upper limit will reach the upper limit of the sonogram. This limit can be displayed with a double click on the frequency scale.

Black Space/Resized Image

The black space left when the image is resized will disappear with a click anywhere in the AS window. It shows that frequencies beyond the image limits will be rejected – see next part.

Moving an Image

Like surface filters, images can be moved vertically and horizontally from the Sonogram window and/or Processing Sequencer.

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