MATLAB Central Newsreader - imwrite

imwrite

Oluwa KuIse — Mon, 09 Mar 2009 17:25:03 -0400

Hello,
Can anyone please help me out with the imwrite function.
When I use it, it creates the file quite alright but it doesn't display the image. I have tried it with both the .png and .jpeg formats. Any suggestions?
Thank you all.
Oluwa KuIse

Re: imwrite

Peter Boettcher — Mon, 09 Mar 2009 17:27:12 -0400

"Oluwa KuIse" <wespeakforex@yahoo.com> writes:

> Hello, Can anyone please help me out with the imwrite function. When
> I use it, it creates the file quite alright but it doesn't display the
> image. I have tried it with both the .png and .jpeg formats. Any
> suggestions?

What problem are you having? imwrite is supposed to create the file.
It is not supposed to display anything. Are you looking for image() or
imshow() instead? Or would you specifically like to do something with
the image file after it is written?

-Peter

Re: imwrite

Oluwa KuIse — Mon, 09 Mar 2009 18:47:01 -0400

Peter Boettcher <boettcher@ll.mit.edu> wrote in message <muy63iili8f.fsf@G99-Boettcher.llan.ll.mit.edu>...
> "Oluwa KuIse" <wespeakforex@yahoo.com> writes:
>
> > Hello, Can anyone please help me out with the imwrite function. When
> > I use it, it creates the file quite alright but it doesn't display the
> > image. I have tried it with both the .png and .jpeg formats. Any
> > suggestions?
>
> What problem are you having? imwrite is supposed to create the file.
> It is not supposed to display anything. Are you looking for image() or
> imshow() instead? Or would you specifically like to do something with
> the image file after it is written?
>
> -Peter

Hi, Peter,
Thanks for your fast response. What I want to do is for MATLAB to be able to display my image in any file I want outside of MATLAB. The results (images) are to be displayed elsewhere and not on MATLAB's figure window. These are the last lines of the program:
source_color = im2uint8([.5 .5 1]);
E = im2uint8(mat2gray(E));
red = E;
green = E;
blue = E;
red(BW) = source_color(1);
green(BW) = source_color(2);
blue(BW) = source_color(3);
rgb_bottom = cat(3, red, green, blue);
imshow(rgb_bottom, 'InitialMag', 'fit')

% Make a second RGB image that is a constant green.
rgb_top = zeros(size(M,1), size(M,2), 3, 'uint8');
rgb_top(:,:,2) = 255;

% Turn the influence or dependence map into an AlphaData channel to be used
% to display with the green image.
M(BW) = 0;
M = imadjust(mat2gray(M), [0 1], [0 .6], 0.5);

image('CData', rgb_top, 'AlphaData', M);

Question: Image() displays the image in a MATLAB figure window. I want to be able to display this image in say, .jpeg.
Thank you!

Re: imwrite

Peter Boettcher — Mon, 09 Mar 2009 19:15:15 -0400

"Oluwa KuIse" <wespeakforex@yahoo.com> writes:

> Peter Boettcher <boettcher@ll.mit.edu> wrote in message <muy63iili8f.fsf@G99-Boettcher.llan.ll.mit.edu>...
>> "Oluwa KuIse" <wespeakforex@yahoo.com> writes:
>>
>> > Hello, Can anyone please help me out with the imwrite function. When
>> > I use it, it creates the file quite alright but it doesn't display the
>> > image. I have tried it with both the .png and .jpeg formats. Any
>> > suggestions?
>>
>> What problem are you having? imwrite is supposed to create the file.
>> It is not supposed to display anything. Are you looking for image() or
>> imshow() instead? Or would you specifically like to do something with
>> the image file after it is written?
>>
>> -Peter
>
> Hi, Peter,
> Thanks for your fast response. What I want to do is for MATLAB to be able to display my image in any file I want outside of MATLAB. The results (images) are to be displayed elsewhere and not on MATLAB's figure window. These are the last lines of the program:
> source_color = im2uint8([.5 .5 1]);
> E = im2uint8(mat2gray(E));
> red = E;
> green = E;
> blue = E;
> red(BW) = source_color(1);
> green(BW) = source_color(2);
> blue(BW) = source_color(3);
> rgb_bottom = cat(3, red, green, blue);
> imshow(rgb_bottom, 'InitialMag', 'fit')
>
> % Make a second RGB image that is a constant green.
> rgb_top = zeros(size(M,1), size(M,2), 3, 'uint8');
> rgb_top(:,:,2) = 255;
>
> % Turn the influence or dependence map into an AlphaData channel to be used
> % to display with the green image.
> M(BW) = 0;
> M = imadjust(mat2gray(M), [0 1], [0 .6], 0.5);
>
> image('CData', rgb_top, 'AlphaData', M);
>
> Question: Image() displays the image in a MATLAB figure window. I want to be able to display this image in say, .jpeg.
> Thank you!

Ah. Use "saveas" or "print" to take a snapshot of your figure window
and export it to a file.

-Peter

Re: imwrite

Adam — Mon, 09 Mar 2009 19:53:01 -0400

"Oluwa KuIse" <wespeakforex@yahoo.com> wrote in message <gp3o75$rr7$1@fred.mathworks.com>...

> Question: Image() displays the image in a MATLAB figure window. I want to be able to display this image in say, .jpeg.
> Thank you!

You probably need to scale your data. imwrite() clips everything outside the range [0, 1]

% compare these two
imwrite(magic(100), 'test.jpg')
imwrite(magic(100)/100^2, 'test2.jpg')

~Adam