The beta 1 version installer was produced this morning. There were a couple of last minute fixes. A bug fix to the auto-metronome. The copyright date was moved to 2014. The users guide was updated.
The new blob counter control in the Imaging Whiteboard (2.5.7) can be used for more advanced image analysis algorithms.
Here we see an image of M&Ms and we want to know how many blue ones are visible. The threshold control is used to separate the blue component of the image. The morphology controls are used to filter out spurious noise and partially visible M&Ms. The blob counter will identify the blobs and allow the user to select the blobs or interest. The selected blobs count is the answer.
Version 2.5.7 includes new image analysis controls including a corner detector. This control implements the Harris corner detector algorithm, described here Harris corner detector – Wikipedia
Here we can see the traditional test image Lenna with significant image features identified.
A new Blob Counter control has been added to the Imaging Whiteboard. This control will allow the user to identify and count blobs within an image.
A live image will be displayed with the total number of blobs displayed dynamically.
Freezing the image will allow the user to select individual blobs which will be identified by outline and ID in the display image.
The Game of Life algorithm is described here: https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life
This control will allow the game of Life to be run on an input image or test pattern. This is an example of emergence https://theconversation.com/emergence-the-remarkable-simplicity-of-complexity-30973
The following sequence shows successive iterations gaining in complexity. The first iteration where live cells exist on the edges of the seed image is predictable, subsequent iterations are not predictable (although they are reproducible). This sequence will run for more than 2000 iterations before becoming stable.
Here we can see the results of two methods applied to the same image shown on the monitor simultaneously. The split screen feature will be available in version 2.5 of the Imaging Whiteboard.
Noise is added to the image and the set memory control will write the noisy image to the secondary memory. The temporal filter is applied to the primary memory. Swap memory switches the primary and secondary memories. The 3×3 median filter is applied. The monitor shows the primary image (morphology result) on the left, and the secondary (temporal filter) on the right.
White noise will contain all frequencies. By applying filters to white noise and viewing the resulting spectrum the effects can be viewed. Here we see the test signal generator producing white noise on 2 channels and the resulting spectrum. The high pass filter is applied to the signal and the resulting spectrum with low frequencies eliminated is shown. The low pass filter is then applied eliminating the high frequencies.
Tracking a target in a raw image may not provide the best tracking performance in all cases. Often tracking a target in a processed image is better. The pre-processing may be edge detection such as a Sobel filter (shown here), or setting a threshold, noise filtering etc.
Using the Set Memory control the original image is saved to memory. The pre-processing (convolution) is performed on the main pixels. The target is tracked in the processed image, but the crop that is passed to the next control is extracted from the image in memory (if it exists). The type of pre-processing will vary depending on the video used.
The latest version (2.3.2) released on this web site (not in the MS store yet) has a new “Low Frequencies Center” option added to the FFT filter control. This option is more convenient for common FFT filters.
By including the low frequencies in the center of the FFT mask window a low pass filter can be implemented.
By excluding the same low frequencies a high pass filter can be implemented.
Keeping the resolution low (256×256 in this case) will provide a reasonable live experience; still not quite real-time.
Now that Imaging Whiteboard 2.0 has been released this would be a good time to blog about some of the new features. The Warper has been improved to include variable warps. Previously only fixed warps were implemented; that is warps such as zoom and rotate where the warp factor is the same for every pixel, see previous blog http://sound-analysis.com/using-complex-arithmetic-to-perform-combination-warps/ . Version 2.0 includes variable warps; that is warps where the warp factor is dependent on the target image location (specifically distance from the center of the target image).
Complex number arithmetic is still used, but, the fixed warp factor is split into two components: Fixed Zoom Factor and Fixed Rotate Factor. These are calculated once. Then for each pixel the variable part of the warp factor is calculated from the user input and the target pixel address. The full warp factor is calculated:
(FixedZoomFactor + variableZoom) * (FixedRotateFactor * variableRotate)
Fish-eye correction can be achieved using the variable zoom. This works well enough, but, is wrong in a number of ways. First it is too simple, real fish-eye correction will take account of the source fish-eye lens properties see Fisheye lens correction (paulbourke.net) if you really want the details. Also, this technique is based on the target pixel location as it implements backward mapped warping (more efficient), real fish-eye correction will use the source image location to determine the correction.
Fish-eye correction is shown in the user manual and further in the cookbook. Here we see biased rotation applied to a chequerboard:
A new control will allow the user to add random noise to the video.
The slider control will modify the amount of noise added from none to only noise.
This control will allow the user to evaluate various noise reduction techniques.
The temporal filter will do a pretty good job with high filter values, but, the problem of movement blurring will be worse at higher levels. This technique is only applicable to video, not single images.
The most obvious spatial technique would be a low pass convolution. This will result in a loss of detail, but is applicable to video or still images.
A couple of morphological operations will do a better job of removing noise, but will result in some image blocking.
The choice of noise reduction technique will depend on the application, the amount of noise anticipated, and personal taste. The Imaging Whiteboard will now allow the user to experiment with various techniques and combinations; varying the parameters and noise level to find the preferred approach.