An example movie which is made with the listed mathematica code below shows traces of moving objects:

https://youtu.be/8jN2uuSHCEg (Melting ...)

http://youtu.be/5ET62846C-I (Crystallisation ...)

The following question is related to:

Speed up calculation

  1. I have thousands of gray scale images.
  2. I want to superpose image_1 to image_50, image_2 to image_51, image_3 to image_52, ..., image_951 to image_1000, ... This is always a set of 50 images.
  3. For the superposition each image is binarized and then colorized differently. The resulting images are col_Image_1, col_Image_2, ... col_Image_50. The color is varying from col_Image_1 to col_Image_50 following a certain color table (see below).
  4. Here is a set of 3 images to illustrate the superposition of circular shaped objects: col_Image_1 has only black and blue pixels, col_Image_2 has only black and green pixels and col_Image_3 has only black and red pixels.

enter image description here

The superposed image shows red over green over blue:

enter image description here

Here you can find a set of 200 gray scale images. http://bit.ly/1CpyIK1 (12.5 MB)

These images I have analyzed with the following code (which produces the expected resulting images (200 images yield 151 superposed images), but is still relatively slow). I have a 4 core i7 processor and have used ParallelTable. For calculating 151 images and writing them to files it takes around 110 sec.

The (until now fastest) solution for the superposition is from https://mathematica.stackexchange.com/users/862/simon-woods

bins = Table[
   Clip[Import[fNames[[i]], "GrayLevels"], {0.18, 0.18}, {0, 
     i/number}], {i, number}];
superImg = 
  Colorize[Image[Map[Max, Transpose[bins, {3, 1, 2}], {2}]], 
   ColorFunction -> (Blend[colTable, #] &)];

My code is given here, which I would like to make faster is here:

ChoiceDialog[{FileNameSetter[Dynamic[imageDir], "Directory"], 

colTable = {{Black}, 
  Table[{Blend[{Blue, Green, Yellow, Red}, x]}, {x, 1/255, 1, 
    1/255}]}; colTable = Flatten[colTable];

fNames = FileNames["*.png"];

numFiles = Length[fNames];
number = 50;


 bins = Table[
   Clip[Import[fNames[[i + j]], "GrayLevels"], {0.25, 0.25}, {0, 
     i/number}], {i, 1, number}];
 superImg = 
  Colorize[Image[Map[Max, Transpose[bins, {3, 1, 2}], {2}]], 
   ColorFunction -> (Blend[colTable, #] &)];

 fileName = 
  StringJoin[imageDir, "/out_", ToString[j + 1], ".png"];

 Export[fileName, superImg, "PNG"];

 , {j, 0, numFiles - number}


You can download all the superposed images here: http://bit.ly/1CoXsSr (15.7 MB)

For example superposed image no. 66 (out of 151 images) is:

enter image description here

A superposition using all 200 images (number = 200) yields:

enter image description here

And now my question: Can my mathematica code be optimized/faster?

  • $\begingroup$ your links don't work $\endgroup$ Commented Jul 8, 2015 at 17:22
  • $\begingroup$ please try it again ... are they working now? $\endgroup$
    – mrz
    Commented Jul 8, 2015 at 17:30
  • $\begingroup$ Not sure, but this might be helpful. $\endgroup$ Commented Jul 8, 2015 at 19:39
  • $\begingroup$ I am not sure if anyone will readily download 40-230 MB large zip-files. A smaller sample might be helpful. $\endgroup$
    – Yves Klett
    Commented Jul 8, 2015 at 21:00
  • $\begingroup$ Thank you for your advice. The zip-files are now 13 MB, 12.5 MB, 15.7 MB $\endgroup$
    – mrz
    Commented Jul 8, 2015 at 22:57


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