iminfo of my image gives
FormatSignature: [73 73 42 0]
Offset: 264322
what is an offset?how this value comes?
It is the signature of a TIFF file. Matlab's way of saying "I endorse this file as TIFF".
Matlab detects the file type by itself, not from the extension. Change the extension to JPG or XYZ, you'll still open it as a TIFF file.
Edit:
This is for PNG for example :
137 80 78 71 13 10 26 10
GIF:
71 73 70 56 57 97 16 0
You can also use an hex editor, open the file, grab the first 8 bytes and convert it from hex to decimal.
Related
I have read quite a lot about LibSVM library, but I would like to ask you for some advices in my particular case. The problem is that I have some 3D medical images (DCE-MRI) of a stomach. My goal is to perform a segmentation of a kidney, and find its three parts. Therefore, I need to train a classifier - I'm going to use SVM and neural network
Feature vectors:
What is available is the pixel (voxel) brightness value (I guess the value range is [0; 511]). In total, there are 71 frames, each taken every second. So the crucial feature of every voxel is how the voxel brightness/intensity is changing during the examination time. In my case, every part of a kidney has a different chart (see an example below), so the way how the voxels brightness is changing over the time will be used by the classifier.
Training sets:
Every training set is a vector of intensity value of one voxel (74 numbers). An example is presented below:
[22 29 21 7 19 12 23 25 33 28 25 5 21 18 27 21 11 11 26 12 12 31 15 15 12 29 17 34 30 11 12 24 35 28 27 26 29 22 15 23 24 14 14 37 241 313 350 349 382 402 333 344 332 366 339 383 383 379 394 398 402 357 346 379 365 376 366 365 360 363 376 383 389 385]
Summary and question to you:
I have many training sets consisting of 74 values from the range [0; 511]. I have 3 groups of voxels, which have a characteristic feature - the brightness is changing in the similar way. What I want to obtain is a classificator, which after getting one voxel vector with 74 numbers, will assess if the voxel belongs to one of these 3 groups, or to none of them.
Question: how to start with LibSVM, any advices? From what I know now is that I should transform input values to be from the range [0; 1] or [-1; 1]. I have many training sets prepared belonging to one of these 3 groups. I will be grateful for any advice, as I'm a newbie and I just need some tips just to start.
You can train and use you model like this:
model=svmtrain(train_label,train_feature,'-c 1 -g 0.07 -h 0');
% the parameters can be modified
[label, accuracy, probablity]=svmpredict(test_label,test_feaure,model);
train_label must be a vector,if there are more than two kinds of input(0/1),it will be an nSVM automatically. If you have 3 classes, you can label them using {1,2,3}.Its length is equal to the number of samples.
The feature is not restricted. It can be what ever you want.
However, you'd better preprocess them to make the results better. For example, you can change range[0:511] to range[0:1] or minus the mean of the feature.
Notice that the testset data should be preprocessed in the same way.
Hope this will help you!
I have the question:
Compute the 16-bit checksum for the data block E3 4F 23 96 44 27 99
F3. Then perform the verification calculation.
I can perform the addition and I get the overflow like:
E3 4F
23 96
44 27
99 F3
``````````
1 E4 FF (overflow)
The solution then takes the overflow and adds it causing E4 FF to become E5 00. Can someone explain to me why this occurs?
My statistics professor wants us to perform a manual Wilcoxon Rank-Sum Test using Matlab. Unfortunately, I have no experience with Matlab whatsoever, and I have been discovering as I go along. In short, we are given a list of 24 paired observations:
33 53 54 84 69 34 60 34 50 56 64 50 76 47 58 63 55 66 58 43 28 80 45
55
66 62 54 58 60 74 54 68 64 60 53 59 61 49 63 55 61 64 54 59 64 46 70
82
I've gotten to the point where I have a matrix with the absolute differences in the first column, the sign of the difference (indicated by a 1 for positive and -1 for negative) in the second column and the rank of the difference (1 through 24) in the third column.
I am struggling with finding a quick and efficient way to "break the ties" between the differences of equal size and allocating the average rank to each of these differences. I expect that some loops and logical statements may be required, but I am having a hard time with them as I have no prior experience.
Any suggestions on how to do this would be much appreciated.
One way to average over the ranks for entries with matching differences is as follows:
irankavg=zeros(length(dp),1);
[dpu,ix,iclass]=unique(dp);
for ii=1:length(dpu)
irankavg(iclass(ii)==iclass) = mean(irank(iclass(ii)==iclass));
end
where dp is a column array that contains the differences
I have the below excel data(and it is my backend)
Date Editor Units
7/1/2013 Amreen 158
7/2/2013 Amreen 23
7/3/2013 Amreen 1
7/6/2013 Amreen 33
7/3/2013 Amreen 77
7/3/2013 Amreen 66
7/3/2013 Anirudh 748
7/3/2013 Amreen 8
7/6/2013 Amreen 402
7/7/2013 Amreen 24
7/7/2013 Amreen 146
7/9/2013 Amreen 33
7/8/2013 Amreen 45
7/8/2013 Amreen 21
I want to create a pivot table using JasperReports. I'm new to this technology or framework(i'm not sure of what it is to be said as), can anybody help me to get the table in the below format with explanation. I'm really confused and unable to understand how to do it.
Amreen Anirudh Anand Total
7/1/2013 158 158
7/2/2013 23 23
7/3/2013 152 748 900
7/4/2013
7/5/2013
7/6/2013 435 435
7/7/2013 170 170
7/8/2013 66 66
7/9/2013 33 33 66
Total 1037 748 33 1818
if not the solution please give me a reference of this type of instances (Excel and JasperReports pivot).
Use the Cross table, with Edit in Column and Date in Row and Unit as sum in the middle.
You should be using Crosstab from the Palette. First create a datasource for you report which can be excel or any RDBMS. Then when you drag and drop the Crosstab from the palette a wizard will open. Just follow the wizard and your Pivot table will be done in no time. I hope this helps. For more info link
I have a problem with ISO encoding in MATLAB.
I have a logging file, with all possible values between 0..255 stored in binary format.
When I open this file in matlab and read one line, MATLAB shows me the correct representation in ISO-8859-1. So far, so good.
For example the value 155 (0x9B) shows the character ">". (Any small character values like this work). Matlab shows this correctly, but when I want process an integer value with double(>) the return value is 8250, which is not an ASCII-Value.
What can I change in the encoding of the file?
edit: the logfile was written with python, in case that matters.
I find the problem. I missed to set the encoding in the fopen command. Working Solution:
%creating testfile
ascii=char([191 210 191 212 191 228 192 215 192 144 198 175 155 236 254 201 10]); %problem value here the 155
logID=fopen('testdatei.log','w','n','ISO-8859-1');
fwrite(logID,ascii);
fclose(logID);
% wrong filehandling
logID=fopen('testdatei.log');
line=fgetl(logID);
decode=double(line);
disp('wrong encoding')
decode(13)
fclose(logID);
%right filehandling
logID=fopen('testdatei.log','r','n','ISO-8859-1');
line=fgetl(logID);
decode=double(line);
disp('right encoding')
decode(13)
fclose(logID);