An online html5 app that demonstrates the use of the 2d fourier transform to filter images.
On the left is the original (or filtered) image on the right the 2d fft image. It shows all the frequencies in the image arranged with the lowest frequency in the center increasing in frequency away from this point towards the edge of the image. Therefore if you mask out the central bit of the FFT image you will lose this low frequency information in the filtered image, effectively doing a high pass filtering, if you only keep this central region then you will pass the low frequencies (low pass filtered image). If you consider the FFT image now as a compass, the direction is related to the 2d fft orientation so by masking out pie shaped regions of the FFT image only frequencies of a certain orientation will be passed in the filtering. To perform the filtering mask out some of the image and click the iFFT button (if you dont mask the image nothing will be filtered and the image will look the same).
To filter an image first upload the image, the tool performs an automatic colour 2d fft which is shown on the image on the right. The controls under the images allow different areas of the FFT image to be masked, by selecting the invert checkbox the mask undoes the masking of other tools. The angle of the arc tools can be adjusted to select only certain orientations. By clicking on the delete icon all drawing objects are removed from the FFT image. By clicking on the black tool the entire fft image is filled. An iFFT is preformed by clicking the iFFT button and if any of the FFT image has been masked the image will be filtered accordingly. At the moment only hard edged tools have been implemented so therefore you can observe some ringing artefacts, at a later date I will introduce a Guassian-like tool to minimise this.
You can Follow the below Step By Step procedure to install the Fourier Image Filtering Chrome Extension to your Chrome Web browser.
It is the Fourier Image Filtering Chrome extension download link you can download and install Chrome Browser.
Tags: Ifft Button , Filter Images , Pass Filtering , Online Html5 App , Central Region , Low Pass , Central Bit , High Pass Filtering , Pass Filtered Image , Fft Image , Filtered Image , Entire Fft Image , Low Frequency Information , Html5 App , Fft Orientation , Filtering Mask , Point Towards ,
Block third-party or all resources of style, script, image, font, xmlhttprequest types
IMTLazarus's remote filtering agent.
IMTLazarus's remote filtering agent. Reimplemented on Manifest V3
IMTLazarus's remote filtering agent.
Net Filter Pro is an advanced web & content filtering engine that understands each content and filters only harmful ones
IMTLazarus's remote filtering agent.
Enhance the feedly website with advanced filtering, sorting and more
Netsweeper Workstation Agent
HK Housing Filtering - Now can support to filter searching results in below Hong Kong housing websites such as 28Hse & 591.
Make searching for places to rent on Craigslist easier by automatically filtering out unwanted results.