how to set dpi of 300 of tiff image in matlab

Hi every one; I have a tiff image which i have created in paint. I do not know its dpi value but i want to set its dpi value tp 300 , Please guide me whether matlab can set its dpi value to 300 or not?? I am asking about some kind of code which resolve my problem Thanks in advance

[Guillaume]

Walter has shown you how to do it in matlab but why do you want to do it?

The dpi is just metadata associated to the image. It has no impact whatsoever on the content of the image. The only thing it does is give a hint to a printer what physical size the image should be. Most software will allow you to override that value in any case when you print.

[Lauren Hirt]

Most likely for publication purposes. For instance, IEEE has strict standards on image quality therefore color images must have a 300 dpi when saved for submission.

Answer 1

[Walter Roberson]

imwrite(TheImage, 'filename.tif', 'Resolution', 300)

[Muhammad Usman Saleem]

@Walter i have already go through this formula available in mathwork. But i not understand this..

• Item one what is the filename.tif
• Item twoWhat is the theImage?

Let say i have tif file with name 2.tif and i want to change its resolution 300 then What will be TheImage in your code provide?

[Walter Roberson]

TheImage = imread('2.tif');
imwrite(TheImage, '2.tif', 'Resolution', 300);

However you might prefer:

tiffObj = Tiff('2.tif', 'r+');
tiffObj.setTag('ResolutionUnit', Tiff.ResolutionUnit.Inch);
tiffObj.setTag('XResolution', 300);
tiffObj.setTag('YResolution', 300);
tiffObj.rewriteDirectory();
tiffObj.close();

[Muhammad Usman Saleem]

@watler i hope new tif image with dpi of 300 will be store in TheImage. Now i want to save this image with 300 dpi in tif format .So that i can put this image in my book .what i do?? Actually i get matrix 485x819x3 uint8 in work space.

[Walter Roberson]

imwrite(TheMatrixYouHaveInYourWorkspace, 'TheNameOfTheNewFile.tif', 'Resolution', 300);

[Muhammad Usman Saleem]

@Walter thanks for contributions.. I am asking about saving of this image with dpi of 300 in tiff format?????????????????

[Guillaume]

@Muhammad, as per my comment to your question, the dpi is just a property attached to an image. It has nothing to do with the pixel size of the image.

You can have a 485x819 image with 300 dpi, or the exact same 485x819 image with 600 dpi, or 1 dpi, or whatever value you want. The pixels will all be the same, the image will look exactly the same. The only thing that will change is the amount of space the image occupy on a piece of paper.

Are you sure that it is the dpi you want to change and not just the size of the image in pixels (if size, see imresize)

[Walter Roberson]

That does save the image with dpi of 300 in tiff format. Your 485x819 image array would come out as 1.62 inches by 2.73 inches when displayed or printed at the 300 dpi listed in its file header.

[Walter Roberson]

If the idea is that the image should use smaller pixels when displayed on the screen, all of the detail but a smaller space, then that is not how computer displays work. If you want to see the image actually displayed at 300 dpi, display it on an Apple Watch, the 42mm version, as that has 302 dpi resolution.

[Muhammad Usman Saleem]

@Walter please see that is requirement from the editor of my book..

Do your illustrations and graphics have
a minimum resolution of 300dpi?

I have made my images in tif format and do not know what the dpi resolutions they have.. I want to convert these tif images into 300 dpi resolutions. For that i required code which change dpi resolution of tif file to 300 and save this image with 300 dpi in tif format?? help me please if you can

[Guillaume]

Well, Walter's code changes the dpi value associated with the image as requested. I would use his second example (the one with tiffObj) as it just touches the property of the image without the unnecessary load and save step.

But really, what your editor is asking is: does your image look good when printed at 300 dpi. That will only depends on how you generated your image to start with. If it's not good enough, there's probably not much you can do to make it look better other than recreate the image with a lot more details. Changing the dpi value of the image will not help in any way.

[Walter Roberson]

An important question here is: how did you generate the images? If your images are photographs generated by a scientific instrument, there may be good reason why they are exactly the the number of pixels they are, and the only thing that needs to be done is set the resolution of 300 like I show above.

If, however, your images are the result of one of the plotting routines, or the result of a screen capture, then you should be generating them at higher resolution. For example if you used print() then you should use the '-r300' option to create them at 300 dpi.

When printed in the book, how large do you want the images to come out? If you want the printed size to come out as 1.62 inches by 2.73 inches then you are fine, just set the Resolution like I show above. But if you want them to come out larger then you need more pixels in the image so that when printed at 300 dpi it comes out the desired size. To increase the number of pixels the best is to start with a source that has more pixels. If you are using a graphics plot then generate it at higher resolution as mentioned above. If you are working with a photo and there just isn't any more information available, then you will need to resize the image, which is something that is likely to introduce artifacts. But if that's what you need to do, have a look at the discussion over There

Answer 2

[ABHILASH SINGH]

print(gcf, '-dtiff', 'myfigure.tiff');