Binary Stream into Matlab
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Good evening,
So far the community has been fantastic in aiding me to learn Matlab so thank you. However a new problem has presented itself, in another program I have saved data to a file using a byte[] array (C#), the file is 100MB large.
The data contained within that file is a depth sensor pixel data stored in a byte[] array and saved to file. I am able to read the file and import the data into a single column and that is as far as I am able to get.
I am looking for assistance in how to visualise the data into possible a imshow()/drawnow method.
Thanks again,
Dan
采纳的回答
Image Analyst
2012-12-10
Why are you reading it into a column when you want a 2D array? You can read directly into a 2D array. Here's a snippet from an m-file of mine:
oneSlice = fread(fileHandle, [x_size y_size], '*uint8');
Ok, then you have a 2D array. Not sure what your difficulty with imshow() is. You can simply do
imshow(oneSlice); % or whatever your matrix is called.
6 个评论
Dan
2012-12-11
Image Analyst
2012-12-11
Not sure what you mean by "reply the depth image" but yes, you can read in a binary image, display it, and do math on it.
Dan
2012-12-11
Image Analyst
2012-12-11
I do have code to read raw binary files into 8 bit and 16 bit volumes and 2D slices if you're interested, but the heart of it is the fread line I already gave you.
Dan
2012-12-11
Image Analyst
2012-12-11
Here is a function that reads a raw binary image with a 3D image in it. User specifies which slice they want and it retrieves that as a 2D image. Instructions for calling it are in the comments at the beginning.
% Read_RAW_Slice
% Reads one slice from a RAW file from disk.
%
% [oneSlice, stHeader] = Read_RAW_Slice(fullFileName, sliceNumber)
% or, alternate usage:
% [oneSlice, stHeader] = Read_RAW_Slice(fullFileName, stInputParameters)
% reads the specified slice from data in 'fullFileName' and
% returns the slice data as a 2D array, and the header as a structure stHeader.
% This method of calling allows for cropping and subsampling.
%
%======== EXAMPLE USAGES =====================================
% Example #1 usage: Simply read a slice. No cropping or subsampling.
% Note that you can pass in just a single number for the second argument and it
% will be the slice number. The Subsampling would then be 1. For example:
% fullFileName = 'SimulatedData_Distance8Bit.RAW';
% [oneSlice, stHeader] = Read_RAW_Slice(fullFileName, 10);
% imshow(oneSlice, []);
%
% Example #2 usage: Read a slice with subsampling in the x, y, and z directions.
% Create a MATLAB structure dynamically to hold the input parameters.
% Use ZStart for the slice number. You don't need to define any other structure members.
% stInputParameters.ZStart = 60;
% stInputParameters.Subsample = 4; % Same for all 3 directions.
% fullFileName = 'SimulatedData_Distance8Bit.RAW';
% [oneSlice, stHeader] = Read_RAW_Slice(fullFileName, stInputParameters);
% imshow(oneSlice, []);
%
% Example #3 usage: Read a slice and crop and subsample it in the x, y, and z directions.
% Create a MATLAB structure dynamically to hold the input parameters.
% stInputParameters.XStart = 200;
% stInputParameters.YStart = 1200;
% stInputParameters.XEnd = 400;
% stInputParameters.YEnd = 1600;
% Use ZStart for the slice number. You don't need to define any other structure members.
% stInputParameters.ZStart = 70;
% stInputParameters.Subsample = 4; % Same for all 3 directions.
% fullFileName = 'SimulatedData_Distance8Bit.RAW';
% [oneSlice, stHeader] = Read_RAW_Slice(fullFileName, stInputParameters);
% imshow(oneSlice, []);
%=============================================================
%
% Image Analyst, 7/30/2007.
%--------------------------------------------------------------------------------------------
function [oneSlice, stHeader] = Read_RAW_Slice(fullFileName, stInputParameters)
% Check syntax. Must have two arguments.
if (nargin ~= 2)
error('Usage: [image2D, stHeader] = Read_RAW_Slice(fullFileName, stInputParameters)');
end
if (ischar(fullFileName) ~= 1)
error('Requires a string filename as an argument.');
end
if ~exist(fullFileName, 'file')
error('Error: file passed in to Read_RAW_Slice\n%s\ndoes not exist.', fullFileName);
end
% Read in header and get 3D image array dimensions.
stHeader = Read_RAW_Header(fullFileName);
% Note: fread() requires that x_size and y_size be doubles.
x_size = double(stHeader.x_size);
y_size = double(stHeader.y_size);
z_size = double(stHeader.z_size);
% Determine the parameters that they passed in.
if isa(stInputParameters, 'double') || isa(stInputParameters, 'integer')
% They didn't pass in a structure - they just passed in a single number (scalar).
% Interpret this number as the slice number.
sliceNumber = int32(stInputParameters);
% For the rest, just take the entire slice.
xStart = int32(1);
yStart = int32(1);
xEnd = int32(x_size);
yEnd = int32(y_size);
Subsampling = int32(1);
else
% They passed in a structure. Make sure they passed in valid numbers.
% Assign defaults to any fields in stInputParameters that they didn't set.
stValidParameters = ValidateInputParameters(stInputParameters, x_size, y_size, z_size);
sliceNumber = int32(stValidParameters.ZStart);
xStart = int32(stValidParameters.XStart);
yStart = int32(stValidParameters.YStart);
xEnd = int32(stValidParameters.XEnd);
yEnd = int32(stValidParameters.YEnd);
Subsampling = int32(stValidParameters.Subsample);
end
% Make sure they asked for a slice that is within range.
if (sliceNumber > z_size)
% Error and exit if they didn't.
error('Slice number must be within the range 1 to %d.\nYou asked for slice %d.', z_size, sliceNumber);
end
% Open file for reading.
fileHandle = fopen(fullFileName, 'rb', stHeader.EndianArg);
if (fileHandle == -1)
error(['Error opening ', fullFileName, ' for input.']);
end
% Skip past header of stHeader.HeaderSize bytes.
bytesToSkip = int32(stHeader.HeaderSize);
fseek(fileHandle, bytesToSkip, 'bof');
% Now, additionally, skip past (sliceNumber - 1) slices
% so that we end up at the beginning byte of the slice that we want.
bytesToSkip = bytesToSkip + int32(x_size * y_size * stHeader.BytesPerVoxel * (sliceNumber - 1));
fseek(fileHandle, bytesToSkip, 'bof');
% Read in image2D image data
% Get original, full-sized 2-D slice.
% Note: fread() requires that x_size and y_size be doubles.
% Note: fread() will return a 2D array if you pass in a 2D array for the number of bytes, as in [x_size y_size].
if stHeader.BytesPerVoxel == 1
oneSlice = fread(fileHandle, [x_size y_size], '*uint8');
elseif stHeader.BytesPerVoxel == 2
oneSlice = fread(fileHandle, [x_size y_size], '*int16'); % It will be a 2D array after this.
else
error('Unsupported BytesPerVoxel %d', stHeader.BytesPerVoxel);
end
% Close the file.
fclose(fileHandle);
% Subsample and/or crop it, if requested.
if Subsampling ~= 1 || xStart ~= 1 || yStart ~= 1 || xEnd ~= x_size || yEnd ~= y_size
oneSlice = oneSlice(xStart:Subsampling:xEnd, yStart:Subsampling:yEnd);
end
return; % from Read_RAW_Slice()
更多回答（1 个）
Walter Roberson
2012-12-10
0 个投票
reshape() to a 2D array, and imshow(TheArray)
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