how to save image

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Ahmed
Ahmed 2011-12-9
编辑： DGM 2024-7-24
hai..
how to save image that pop up at frame show figure. I try to used this function,but the saved image not follow the dimension(X x Y) of original image.
saveas(gcf,'mask_image.jpg', 'jpg')
thank

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Jan
Jan 2011-12-9
Image = getframe(gcf);
imwrite(Image.cdata, 'mask_image.jpg');
Another method:
printf(gcf, '-djpeg100', 'mask_image.jpg', '-r0');
But the later is not guaranteed to have exactly the same size. There are some rounding effects between the units of the figure and the pixel resolution.
See: help print and help imwrite.
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Clinton Connelly
Clinton Connelly 2021-9-30
You could just use the built-in "imwrite" function to save any loaded image, or specifically a 'uint8' file, to a file of any choice:
Image = imread("ImageName.jpg");
imwrite(Image, "NewImageName.jpg");
This code doesn't return the max resolution of the file, but there is a parameter for that:
Image = imread("ImageName.jpg");
imwrite(Image, "NewImageName.jpg", "Quality", 100)
The interval of values for quality is between 0 and 100, inclusive, with the result being self-explanatory
Other information could be found in matlab by typing the input "help imwrite" and doing some reading...
There's also a text file called libtiffcopyright.txt, but I don't know where to find that
DGM
DGM 2024-7-24
编辑：DGM 2024-7-24
Using figure capture to JPG for saving images is only a smidge less ridiculous than using your phone to take a skewed photo of your monitor.
I second @Clinton Connelly here. Depending on the scenario (version, environment, image size, figure style), neither saveas(), print(), nor getframe() are guaranteed to return an image of the correct geometry. The data scale, class, and number of channels may be altered. The image resolution will be altered, and there will likely be a random amount of padding added. There is rarely a good reason to save images by taking a screenshot. Just use imwrite().
https://www.mathworks.com/matlabcentral/answers/2136528-how-to-save-an-image-without-axis-or-white-space
To make matters worse, it's implied by the naming that this image is a binarized image. I see no good reason to be saving binary images as JPG. A PNG is lossless and will produce a smaller file with flat-colored image content. Even if it's not binarized, I'm still going to assert that most people are not making an informed decision to permanently damage their images with a downsampled JPG.
https://www.mathworks.com/matlabcentral/answers/82439-saving-an-axes-as-jpg-file-using-saveas#comment_2806143
https://www.mathworks.com/matlabcentral/answers/789399-exporting-only-the-plot-legend-to-a-jpg-file#answer_1266448
https://www.mathworks.com/matlabcentral/answers/1838783-save-a-fig-image-to-a-jpg-image-while-maintaining-size-and-resolution#answer_1087093
https://www.mathworks.com/matlabcentral/answers/268137-how-to-segment-black-pixels-from-a-colour-image
https://www.mathworks.com/matlabcentral/answers/1987548-how-to-convert-logical-form-to-binary-form-image#answer_1261663
https://www.mathworks.com/matlabcentral/answers/182252-resolution-of-a-matlab-created-jpg#comment_2812598
https://www.mathworks.com/matlabcentral/answers/2037031-blurry-figures-when-concatenating-images#answer_1338586
https://www.mathworks.com/matlabcentral/answers/272379-why-is-the-image-blurred-after-rgb-to-hsi-conversion#answer_1373807
Setting the 'Quality' parameter to 100 does not create a faithful reproduction. The only way to produce a lossless image with full spatial resolution in the chroma channels is to specify the 'lossless' flag, which (iirc) produces a JP2 file instead of a baseline JPG. Everything else that imwrite() produces is a 4:2:0 downsampled JPG, even at 100% quality.

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