error in writing an image

I have an error in the code below in writing an image please help

imwrite((gsq, []),strtemp)

Expression or statement is incorrect--possibly unbalanced (, {, or [

I have posted question regarding this and have got answer,but still getting same error

Answer 1

[Image Analyst]

Why do you have the () and [] in there? You're supposed to be passing a numerical array and a string that is the filename. Did you look up the help for imwrite?

[Pat]

if i am not using [ ] ,the image is black in colour,if i use i get the image,i could not find any in imwrite

[Walter Roberson]

Sounds like you are trying to use [] to do the equivalent of imagesc(), scaling the image. imwrite() does not support any such option. You have to scale the data before you write it.

[Jan]

"(gsq, [])" is simply no valid expression in Matlab. What do you expect it to do?

[Pat]

this is my code

clc

clear all

pathname ='D:\dataset1\' ;

dirlist = dir( [pathname '*.jpg'] );

pickind='jpg';

for m = 1:length(dirlist)

im = double((imread([pathname, dirlist(m).name])))/256;

im=rgb2gray(im);

[xg, yg] = gradients_xy(im, 5, false, [1 size(im,1) 1 size(im,2)]);

gsq = xg.^2 + yg.^2;

%imshow(gsq, []);

% figure, imshow(gsq, []),%title('org image')

strtemp=strcat('D:\shape\',int2str(m),'.',pickind);

imwrite((gsq ,[]),strtemp)

end

i get erro if i use "(gsq, [])" ,only if i use this code,i get the image,if i use gsq i get only white coloured image

i want to write this image to a folder please help

[Walter Roberson]

Already answered when you asked it in http://www.mathworks.com/matlabcentral/answers/23562-how-to-introduce-delay

Key phrase in my response:

"Warning: there is no way to tell imwrite() that you want the image to be automatically scaled the way you would by using [] as an argument to imshow()."

I have posted scaling code several times, and there are file exchange contributions to do the scaling, such as http://www.mathworks.com/matlabcentral/fileexchange/7943-freezecolors-unfreezecolors

[Pat]

walter can u tell why the image is black in colouw when using imshow(gsq),and i get image wen i use imwrite(gsq ,[])

I have resized the image but i get same black image ,please ezplain

[Image Analyst]

You use [] when displaying a floating point image in imshow. That will scale it for display. Otherwise it expects the image to be in the range 0-1 and if you have values outside that it will clip them and only show you the pixels that ARE within the range 0-1, which may be very very few, if any, pixels. So, you basically see all black if you don't use [] with imshow and you're displaying a floating point image. Now, with your imwrite, it normally wants an integer image. Exactly what do you think you're doing when you do (gsq, [])? Why are you doing that instead of simply gsq? Why??? We've told you a few times now: use [] with imshow, NOT with imwrite. Please believe us. And why didn't you cast gsq into an integer, scaling it if necessary, like Walter suggested? Please please do that. At least give it a try. If you really need to save it as a floating point image for later use in MATLAB, then I recommend saving the variable in a .mat file using save() instead of using imwrite().

[Pat]

Thanks a lot