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Jan Motl

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27 Oct 2014 Screenshot Rotate an image around a point Performs rotation of an image around any point inside of the image. Author: Jan Motl image processing, rotation, image, transformation 65 8
  • 5.0
5.0 | 7 ratings
24 Oct 2014 Screenshot Bernsen local image thresholding Implementation of Bernsen's thresholding method. Author: Jan Motl image processing, local thresholding, binarization 25 2
  • 2.5
2.5 | 2 ratings
01 Apr 2014 Screenshot Remove ghosts from binarized images This method removes speckles in the binarized images. Author: Jan Motl binarization, thresholding, image processing 13 2
26 Jun 2013 Screenshot Bradley local image thresholding A fast an well performing local image thresholding method. Author: Jan Motl binarization, local thresholding, image processing, sauvola 64 3
  • 4.66667
4.7 | 3 ratings
05 Jun 2013 Screenshot Nick local image thresholding Nick's binarization performs local image thresholding. Author: Jan Motl binarization, local thresholding, image processing 16 0
Comments and Ratings by Jan Motl View all
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27 Oct 2014 Rotate an image around a point Performs rotation of an image around any point inside of the image. Author: Jan Motl

Thanks Maider for the comment.

Regarding the small angle problem, I believe that for small angles (like 0.1) and small images (like 300x200) rotateAround should give images identical with the source images (and also identical with the results from imrotate).

Only for bigger images (like 1000x1000) or bigger angles (like 1) the results should be different.

Regarding the loosing of pixels. If I rotate an image by 0 degrees, I should always get the original image (regardless of the point of rotation or image size). With round function, I am not loosing any pixel on testing machines. With floor function, I am loosing pixels.

But it is possible, that internals of imrotate can differ in rounding.

Nevertheless, the function as it is behaves correctly in MATLAB R2012b and MATLAB R2014a.

24 Oct 2014 Bernsen local image thresholding Implementation of Bernsen's thresholding method. Author: Jan Motl

I have retested Bersen thresholding on several operating systems and versions of MATLAB. In all configurations it worked.

But keep in mind that only 2-dimensinal matrices in uint8 are supported. However, if you load a jpg file with imread command then you get a 3-dimensional uint8 matrix (even if the image is grayscale). Hence you have reduce dimensionality.

Also, it is generally advisable to test several sizes of the neighborhood to get good results.

For example, to get the illustration image from the attached jpg, use following command:
imshow(bernsen(rgb2gray(imread('image.jpg')), [93, 93]));

The description of the algorithm (and the parameters) is for example at:
http://fiji.sc/wiki/index.php/Auto_Local_Threshold#Bernsen

If you are still having difficulties with the code, let me know more details (like version of MATALB, OS, example image, the minimal code reproducing the error,...) and I will do my best to help you.

21 Apr 2014 Rotate an image around a point Performs rotation of an image around any point inside of the image. Author: Jan Motl

Thanks for suggestion. I swapped the parameters of the function call.

01 Apr 2014 Remove ghosts from binarized images This method removes speckles in the binarized images. Author: Jan Motl

Thanks for reporting. I have added the missing example image. Let me know if you have more issues.

05 Jun 2013 Bradley local image thresholding A fast an well performing local image thresholding method. Author: Jan Motl

You can try to increase the size of the sliding window. Don't be afraid to increase the windows size to hundreds to hundreds pixels - the window should be bigger than the biggest symbol in the image.

Or you can try the post-processing step from Yanowitz and Bruckstein's binarization method: http://www.mathworks.com/matlabcentral/fileexchange/41786-remove-ghosts-from-binarized-images

Basically it looks at the edge of each foreground object. And if the average gradient along the edge is small, it concludes that it's false foreground object and deletes the object.

Comments and Ratings on Jan Motl's Files View all
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11 Dec 2014 Bradley local image thresholding A fast an well performing local image thresholding method. Author: Jan Motl Michael scheinfeild

excellent code help binarize image

27 Oct 2014 Rotate an image around a point Performs rotation of an image around any point inside of the image. Author: Jan Motl Bauyrzhan Aubakir

27 Oct 2014 Rotate an image around a point Performs rotation of an image around any point inside of the image. Author: Jan Motl Jan Motl

Thanks Maider for the comment.

Regarding the small angle problem, I believe that for small angles (like 0.1) and small images (like 300x200) rotateAround should give images identical with the source images (and also identical with the results from imrotate).

Only for bigger images (like 1000x1000) or bigger angles (like 1) the results should be different.

Regarding the loosing of pixels. If I rotate an image by 0 degrees, I should always get the original image (regardless of the point of rotation or image size). With round function, I am not loosing any pixel on testing machines. With floor function, I am loosing pixels.

But it is possible, that internals of imrotate can differ in rounding.

Nevertheless, the function as it is behaves correctly in MATLAB R2012b and MATLAB R2014a.

24 Oct 2014 Bernsen local image thresholding Implementation of Bernsen's thresholding method. Author: Jan Motl Jan Motl

I have retested Bersen thresholding on several operating systems and versions of MATLAB. In all configurations it worked.

But keep in mind that only 2-dimensinal matrices in uint8 are supported. However, if you load a jpg file with imread command then you get a 3-dimensional uint8 matrix (even if the image is grayscale). Hence you have reduce dimensionality.

Also, it is generally advisable to test several sizes of the neighborhood to get good results.

For example, to get the illustration image from the attached jpg, use following command:
imshow(bernsen(rgb2gray(imread('image.jpg')), [93, 93]));

The description of the algorithm (and the parameters) is for example at:
http://fiji.sc/wiki/index.php/Auto_Local_Threshold#Bernsen

If you are still having difficulties with the code, let me know more details (like version of MATALB, OS, example image, the minimal code reproducing the error,...) and I will do my best to help you.

23 Oct 2014 Bernsen local image thresholding Implementation of Bernsen's thresholding method. Author: Jan Motl Rohan Ghare

not working proper
what are different parameters of bernsen

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