How to read a mraw file

I have a video in .mraw and I would like to read it and exploit it but with the function I found, does not work because it is .cih and i have .cihx if someone could help me please

thank you in advance

[Mathilde Schneider]

Hi Lylia,

I'm facing the same issue, and using the readmraw doesn't seems to work. Have you managed to figure it out?

Regards,

Mathilde

[Phil Kreth]

Mathilde,

Please see my reply below. I edited SEP's readmraw.m function to handle .cihx files (as well as corner cases for newer .cih files).

Cheers,

Phil

Answer 1

[Shadaab Siddiqie]

From my understanding you want to read .mraw file. You can refer to the code bellow.

I=readmraw('Photron_mraw_example',[1 10]);
for n=1:1:10
imshow(I.Images.RawImages(:,:,n),[0 3000]);
pause(.1);
end

Here readmraw function is from Photron MRAW File Reader.

Answer 2

[Phil Kreth]

Hi everyone. I have edited the readmraw function that was written by "SEP" to handle either .cih or .cihx files. The originally function is posted on the FileExchange here - https://www.mathworks.com/matlabcentral/fileexchange/42408-photron-mraw-file-reader

Below is a copy of the new readmraw.m file that you can use.

function imgs = readmraw(filename, numImgs)
%   readmraw.m 
%   READMRAW Read Photron MRAW files into MATLAB
%   
%   imgs = READMRAW('C:\Photron\Filename.mraw', [a,b]) loads images a
%   through b from 'C:\Photron\Filename.mraw' into matrix imgs. 
%
%   Remarks
%   -------
%   This function must be handed the common *.cih(x) and *.mraw file name 
%   and the range of images to be loaded (MATLAB may not handle the entire
%   image range for large files). 
%   NOTE: Both the *.cih(x) file and the *.mraw file are utilized
%   Autor: SEP                                Creation Date: Jun 20, 2013
%   Editor: Phil Kreth                    Modification Date: Sep  9, 2024
%
%   Examples
%   --------
%   % Load all images
%   imgs = readmraw('C:\Photron\Moviefile.mraw', 0); 
% 
%   % Load images 10 through 50
%   imgs = readmraw('C:\Photron\Moviefile.mraw', [10,50]);
% 
%   % Load image 10
%   imgs = readmraw('C:\Photron\Moviefile.mraw', 10);
% 

fid1 = fopen(sprintf('%s.cih',filename(1:end-5)),'r');
if fid1 < 0
    fid1 = fopen(sprintf('%s.cihx',filename(1:end-5)),'r');
    cihx = true;
else
    cihx = false;
end
fid2 = fopen(sprintf('%s',filename),'r');
if fid1 < 1 || fid2 < 1
    error(['Could not locate .CIH or .CIHX header for file: ''' filename '''']);
end

if ~cihx % CIH FILE
    % Read Header Information
    Header = textscan(fid1,'%s','delimiter',':');
    Header = Header{1};

    color_ind = find(contains(Header, 'Color Type')) + 1;
    if strcmp(cell2mat(Header(color_ind(1))), 'Color')
        color = true;
    else
        color = false;
    end

    bit_ind = find(contains(Header, 'Color Bit')) + 1;
    bits = str2double(cell2mat(Header(bit_ind(1))));
    if color
        bits = bits/3;
    end
    bit_depth = sprintf('ubit%d', bits);

    frame_ind = find(startsWith(Header, 'Total Frame')) + 1;
    Total_Frames = str2double(cell2mat(Header(frame_ind(1))));

    width_ind = find(contains(Header, 'Image Width')) + 1;
    Width = str2double(cell2mat(Header(width_ind(1))));

    height_ind = find(contains(Header, 'Image Height')) + 1;
    Height = str2double(cell2mat(Header(height_ind(1))));

    % fps_ind = find(contains(Header, 'Record Rate(fps)')) + 1;
    % fps = str2double(cell2mat(Header(fps_ind(1))));
    
else % CIHX FILE
    % Read Header Information
    Header = textscan(fid1,'%s','delimiter',{'<','>'});
    Header = Header{1};

    color_ind = find(contains(Header, 'type')) + 1;
    if strcmp(cell2mat(Header(color_ind(1))), 'Color')
        color = true;
    else
        color = false;
    end

    bit_ind = find(contains(Header, 'bit')) + 1;
    bits = str2double(cell2mat(Header(bit_ind(1))));
    if color
        bits = bits/3;
    end
    bit_depth = sprintf('ubit%d', bits);

    frame_ind = find(contains(Header, 'totalFrame')) + 1;
    Total_Frames = str2double(cell2mat(Header(frame_ind(1))));

    width_ind = find(contains(Header, 'width')) + 1;
    Width = str2double(cell2mat(Header(width_ind(1))));

    height_ind = find(contains(Header, 'height')) + 1;
    Height = str2double(cell2mat(Header(height_ind(1))));

    % fps_ind = find(contains(Header, 'recordRate')) + 1;
    % fps = str2double(cell2mat(Header(fps_ind(1))));
end

Pixels = Width*Height;

fclose(fid1);


% Define Image Range
if numImgs == 0             % load all the images 
    first_frame = 1;
    frames = Total_Frames;
elseif length(numImgs) == 1 % load a single image
    first_frame = numImgs;
    frames = 1;
else                        % load a specified range of images
    first_frame = numImgs(1,1);
    last_frame = numImgs(1,2);
    frames = last_frame-first_frame+1;
end


% Load Images
bytes_offset = (first_frame-1)*Pixels*bits/8;
if color
    bytes_offset = bytes_offset*3;
end
fseek(fid2, bytes_offset, 'bof');

if bits > 8
	data_fmt = 'uint16';
else
	data_fmt = 'uint8';
end

if color
    imgs = zeros(Pixels*3, frames, data_fmt);
    for n = 1:frames
        imgs(:,n) = fread(fid2, Pixels*3, bit_depth, 0, 'b');
    end
    imgs = [imgs(1:3:end,:); imgs(2:3:end,:); imgs(3:3:end,:)]; % separate color channels
    imgs = reshape(imgs, [Width*Height 3 frames]); % reshape to separate color channels
    N = [Width Height 3 frames];
    imgs = permute(reshape(imgs, N), [2 1 3 4]); % standard reshape and permute
else 
    imgs = zeros(Pixels, frames, data_fmt);
    for n = 1:frames
        imgs(:,n) = fread(fid2, Pixels, bit_depth, 0, 'b');
    end
    N = [Width Height frames];
    imgs = permute(reshape(imgs, N), [2 1 3]);
end

fclose(fid2);

Cheers,

Phil

*Note: I updated this code on September 9, 2024 to handle an edge case that was found when trying to read all images with a version 3 CIH file. Sometimes, you may have encountered an error if you saved a couple copies of the MRAW and one of those had fewer frames than an earlier copy. Loading all frames with a 0 entered for the second argument could produce an error as the code would have looked for the larger number of frames instead of the correct one.

[Phillip]

Phil -- thanks for sharing this, you've saved me likely a few hours work!

Sincerely,

Another Phil.

[Gabriele Pisetta]

Amazing script! works flawlessly!

Thanks

[Jonny Cheng]

Hello Phil,

Thanks for your contributions on the scripts.

I have modified the code to read the cih file for a Photron SA-Z color camera. However, for the same camera with cihx file. The image shows wired color and lower resolution. Could you check my code and tell what is wrong?

function imgs = readmrawcihx2(filename, numImgs)

% readmraw.m

% READMRAW Read Photron MRAW files into MATLAB

%

% imgs = READMRAW('C:\Photron\Filename.mraw', [a,b]) loads images a

% through b from 'C:\Photron\Filename.mraw' into matrix imgs.

%

% Remarks

% -------

% This function must be handed the common *.cih(x) and *.mraw file name

% and the range of images to be loaded (MATLAB may not handle the entire

% image range for large files).

% NOTE: Both the *.cih(x) file and the *.mraw file are utilized

% Autor: SEP Creation Date: June 20,2013

% Editor: Phil Kreth Modification Date: Aug 31, 2021

%

% Examples

% --------

% % Load all images

% imgs = readmraw('C:\Photron\Moviefile.mraw', 0);

%

% % Load images 10 through 50

% imgs = readmraw('C:\Photron\Moviefile.mraw', [10,50]);

%

% % Load image 10

% imgs = readmraw('C:\Photron\Moviefile.mraw', 10);

%

fid1 = fopen(sprintf('%s.cih',filename(1:end-4)),'r');

if fid1 < 0

fid1 = fopen(sprintf('%s.cihx',filename(1:end-5)),'r');

fid2 = fopen(sprintf('%s.mraw',filename(1:end-5)),'r');

cihx = true;

else

fid1 = fopen(sprintf('%s.cih',filename(1:end-4)),'r');

fid2 = fopen(sprintf('%s.mraw',filename(1:end-4)),'r');

cihx = false;

end

%fid2 = fopen(sprintf('%s.mraw',filename(1:end-5)),'r');

if fid1 < 1 && fid2 < 1

error(['Could not locate .CIH or .CIHX header for file: ''' filename '''']);

end

if ~cihx % CIH FILE

% Read Header Information

Header = textscan(fid1,'%s','delimiter',':');

Header = Header{1,1};

color_ind = find(contains(Header, 'Color Type')) + 1;

if strcmp(cell2mat(Header(color_ind(1))), 'Color')

color = true;

else

color = false;

end

bit_ind = find(contains(Header, 'Color Bit')) + 1;

bits = str2double(cell2mat(Header(bit_ind(1))));

if color

bits = bits/3;

end

bit_depth = sprintf('ubit%d', bits);

frame_ind = find(contains(Header, 'Total Frame')) + 1;

Total_Frames = str2double(cell2mat(Header(frame_ind(1))));

width_ind = find(contains(Header, 'Image Width')) + 1;

Width = str2double(cell2mat(Header(width_ind(1))));

height_ind = find(contains(Header, 'Image Height')) + 1;

Height = str2double(cell2mat(Header(height_ind(1))));

% fps_ind = find(contains(Header, 'Record Rate(fps)')) + 1;

% fps = str2double(cell2mat(Header(fps_ind(1))));

else % CIHX FILE

% Read Header Information

Header = textscan(fid1,'%s','delimiter',{'<','>'});

Header = Header{1};

color_ind = find(contains(Header, 'type')) + 1;

if strcmp(cell2mat(Header(color_ind(1))), 'RawBayer')

color = true;

else

color = false;

end

bit_ind = find(contains(Header, 'bit')) + 1;

bits = str2double(cell2mat(Header(bit_ind(1))));

if color

bits = bits/3;

end

bit_depth = sprintf('ubit%d', bits);

frame_ind = find(contains(Header, 'totalFrame')) + 1;

Total_Frames = str2double(cell2mat(Header(frame_ind(1))));

width_ind = find(contains(Header, 'width')) + 1;

Width = str2double(cell2mat(Header(width_ind(1))));

height_ind = find(contains(Header, 'height')) + 1;

Height = str2double(cell2mat(Header(height_ind(1))));

% fps_ind = find(contains(Header, 'recordRate')) + 1;

% fps = str2double(cell2mat(Header(fps_ind(1))));

end

Pixels = Width*Height;

fclose(fid1);

% Define Image Range

if numImgs == 0 % load all the images

first_frame = 1;

frames = Total_Frames;

elseif length(numImgs) == 1 % load a single image

first_frame = numImgs;

frames = 1;

else % load a specified range of images

first_frame = numImgs(1,1);

last_frame = numImgs(1,2);

frames = last_frame-first_frame+1;

end

% Load Images

bytes_offset = (first_frame-1)*Pixels*bits/8;%

if color

bytes_offset = bytes_offset*3;

end

fseek(fid2, bytes_offset, 'bof');

if bits > 8

data_fmt = 'uint16';

else

data_fmt = 'uint8';

end

if color

imgs = zeros(Pixels*3, frames, data_fmt);

for n = 1:frames

imgs(:,n) = fread(fid2, Pixels*3, bit_depth, 0, 'b');

end

imgs = [imgs(1:3:end,:); imgs(2:3:end,:); imgs(3:3:end,:)]; % separate color channels

imgs = reshape(imgs, [Width*Height 3 frames]); % reshape to separate color channels

N = [Width Height 3 frames];

imgs = permute(reshape(imgs, N), [2 1 3 4]); % standard reshape and permute

else

imgs = zeros(Pixels, frames, data_fmt);

for n = 1:frames

imgs(:,n) = fread(fid2, Pixels, bit_depth, 0, 'b');

end

N = [Width Height frames];

imgs = permute(reshape(imgs, N), [2 1 3]);

end

fclose(fid2);

[Phil Kreth]

Jonny,

I know I'm super late with my reply here, but I can't find what's going on with your code unless I have an example file to work with. I don't have access to a color SA-Z, so it's challenging to guestimate what I might need to modify. Can you share a CIH(X) and MRAW with me? Anything that's got a couple of frames would be fine, and I would recommend uploading to a public resource like Google Drive.

Thanks,

Phil

Answer 3

[Turbulence Analysis]

Hi,

With this function, I am getting the below error

Unable to perform assignment because the size of the left side is 589824-by-1 and
the size of the right side is 17977-by-1.

Error in readmraw (line 126)
        imgs(:,n) = fread(fid2, Pixels, bit_depth, 0, 'b');
 

[Phil Kreth]

Hi there, Turbulence Analysis,

Sorry for the late reply. I don't monitor this site.

It looks like the code was anticipating a much larger image than what was being fed in through the fread() command. The interesting thing about the fread() output there being 17977x1 is that 17977 is a prime number, so there's no way it could be divided up (by bit depth, by color vs grayscale, or by any width & height combination). What were the characteristics of the file you were trying to feed in (W, H, Number of Frames, Bit Depth, Color vs Grayscale)?

Best,

Phil

[Clarice du Plessis]

Hi Turbulence Analysis

I got the same error when I specified the filename as .cihx. Changing it to .mraw solved the issue for me.

Regards

Clarice