i want to alter dpi

how can i alter dpi of an image and set it to 300.

Answer 1

[Sean de Wolski]

In print? Specify the rnumber

print(gcf,'-r300')

[nayana]

not in print i have to save it on my disk. the dpi property of the image should be adjusted to 300 and it should be saved

[Sean de Wolski]

Yes. You save a figure as an image with the print command:

figure;
surf(peaks);
print(gcf,'-r300','-dpng','test.png')

And for more info:

doc print

Answer 2

[Walter Roberson]

dpi is not an physical property of images, and cannot be set by imwrite() or print(). In some kinds of images, dpi can be set in auxillary information headers, such as EXIF headers. Unfortunately MATLAB does not have any routines that can write those headers. See http://www.mathworks.com/matlabcentral/newsreader/view_thread/298784