I'm looking for a raw image file format as simplistic as PGM, but encoded in binary, so that I can write pixels in bursts.
I've searched over Wikipedia and Google and found none that didn't start to have complex headers and such.
Can anybody recommend me such a type of a file format?
One easy way is to use the PGM format itself, in 'P5' (binary) mode. See PGM format from the Netpbm documentation. Set maxVal to 255, to use the full 8 bit range.
This is probably the most common format for PGM, as it is extremely easy and fast to both read and write.
Related
I am working on a compression project, and I used the default save() function in Matlab for the purpose of lossless (entropy) encoding. The transform module is all figured out.
I used the save() function to encode a 3d array that includes a bunch of zeros. I am sure that Matlab is using some kind of lossless compression with the save() function since, when I save that array, it ends up taking far less space than an array, say, containing no zeros at all. I had no success finding out what type of entropy encoding schemes are behind the function. Because it is a core part of the algorithm, I think I must at least know what is behind the function.
Plus, if you know any other type of entropy encoder that would do a better job in compressing a 3d array that contains zeros, I would really appreciate you sharing. Or, if you think I could easily write the code for that myself, then please let me know.
The v7 format uses deflate.
The v7.3 format uses the HDF5 format, which supports gzip (deflate) and szip compression. It also has an option to not compress.
The MATLAB save function supports compression for some of the formats that are available. Specifically, -v7 (default format) and -v7.3 support compression. The details of the compression are not documented.
I have raw image data, a pixel array (actually a single string of data) that I want to convert to the most basic and minimal DNG format/file. I saw different approaches utilizing libtiff and libjpeg.
Is there a simpler and more straight forward way to do this in SWIFT using Core Graphics, Core Image or yet another SWIFT API?
The image data are still in the original Bayer matrix format (CFA pattern is RGGB) without any tags.
I downloaded the over 100 pages of the latest Adobe DNG format specification, but I cannot find the actual byte order or structure of the DNG file in there... I am pretty lost with this document.
Any help and hints are highly appreciated.
I have a file that is in AVL file format from a program called ArcGIS (formerly ArcView) that I need to convert to a mat file. It contains data I need to play back. Can anybody suggest a simple way to convert the file? I have done quite a bit of searching, and it seems the AVL is not a binary, aka it is a text format, which means I could write a program to convert it, but only if I also knew the corresponding matlab MAT file format. Moreover, this could take quite a while to do, and I need to file to be converted quickly so I can use the data.
I have to analyze bio acoustic audiofiles using matlab. Eventually I want to be able to find anomalies in the audio. That's the reason I need to find a way to represent the audio in a way I can extract and compare features. I'm dealing with mp3 files up to 150 mb. These files are too large for matlab to read in to it's memory. Therefore I want to use the memmapfile() function. I used the following code and a small mp3 file to find out how it actually works.
[testR, ~] = audioread('test.mp3');
testM = memmapfile('test.mp3');
disp(testM.Data);
disp(testR);
The actual values of the testM.Data and testR are different. Audioread() returns a 7483391 x 2 matrix and memmapfile() a 4113874 x 1 matrix.
I'm not really sure how memmapfile() works, I expected this to be equal to each other. Is there a way to read mp3 files in the same format audioread() does using memmapfile()? And what does memmapfile actually return in case of an audio file? Maybe it's also usable in the vector format in the case of anomaly detection?
Thanks in advance!
NOTE: The original files were in wav IMA ADPCM format with sizes from 1.5 up to 2.5 gb. Since Matlab can't deal with that format and the size of the files I converted them to 8bit mp3 files.
I think that the problem is mammapfile by default read data in uint8 format, while audioread function read data in another way.
How you can see here you can specify the format of data when you read it with memmapfile, so try to "play" with different values. From the documentation I read that you can read data in double format, so try to modify the memmapfile data format and audioread data format.
Last thing, memmapfile always organize the data in matrix like "somenumbers x 1", so if you want the original one you need to use something like reshape.
Anyway if you work with big data I suggest you to try with something different instead memmapfile, because it is very very slow
At work I have to record a lot of data from png data. Every time I have to manually record the digits (e.g. mean\SD 101.1\11) on the excel sheet and read it with Matlab. Would it be possible that Matlab could directly read the digits from the PNG image, so that lots of work could be saved?
I know it might involve pattern recognition, but still hope that there may be someone who has done this before.
You can make use of Optical Character Recognition (OCR). The code for it is available here