imwrite

Write image to graphics file.

📝 Syntax

• imwrite(A, filename)

• imwrite(A, map, filename)

• imwrite(..., fmt)

• imwrite(..., , propertyName, propertyValue)

📥 Input argument

• A - matrix: 3D for color and 2D for gray or indexed image.

• map - Colormap of indexed image:m-by-3 array.

• fmt - Format of output file: 'bmp', 'png', 'jpg', 'gif', ...

• filename - a row vector characters or scalar string: name of graphics file.

• propertyName - a scalar string or row vector character.

• propertyValue - a value.

📄 Description

imwrite(A, filename) writes image dataA to the file specified by filename

Property name:

Quality: quality of output file: scalar in the range [0, 100] (75 as default).

Alpha: matrix of values in the range [0, 1]: Transparency of each pixel.

Comment: character vector, string scalar, cell array of character vectors or string array: Comment added to image.

Author: character vector or string scalar: Author information.

Properties for gif format:

WriteMode:

LoopCount:

DelayTime:

💡 Examples

f = figure();
A = rand(69, 69);
A(:,:,2) = rand(69,69);
A(:,:,3) = rand(69,69);
imshow(A);
imwrite(A, [tempdir, '69x69-RGB.png']);

gif animation

movie_directory = [modulepath('graphics'), '/examples/', 'movie/'];
sequences = {'dance', 8; 'leap', 9};
frameIdx = 0;
filename_gif = [tempdir, 'gif_animation.gif'];
for s = 1:size(sequences, 1)
    action = sequences{s, 1};
    nb_frames_action = sequences{s, 2};

    for i = 1:nb_frames_action
        % Construct the filename for the current frame
        filename = fullfile(movie_directory, sprintf('%s_%d.png', action, i));

        % Read the image and store it in the movie structure
        [image, map] = imread(filename);
        % Read the image
        [A, map] = imread(filename);
        if frameIdx == 1
            imwrite(A,map,filename_gif,"gif", 'LoopCount', Inf, 'DelayTime', 1);
        else
            imwrite(A,map,filename_gif,"gif", 'WriteMode', "append", 'DelayTime', 1)
        end
        frameIdx = frameIdx + 1;
    end
end
if ispc()
  unix(filename_gif);
else
  unix(['xdg-open ', filename_gif]);
end

🔗 See also

imread, imshow, imformats.

🕔 History

Version	📄 Description
1.0.0	initial version
1.13.0	gif animation, pcx format added