Matlab doubt about imread function

[abhigopal]

Hi,

I used the imread function to read an image matrix of size 256 X 256. The image matrix was easily displayed. But when I wanted to perform some operations to this image, it gave me an error saying that the data type was a uint8 - unsigned 8 bit integer. So i converted everything to double and it worked ok. Now, the resulting matrix after all my operations performed is of double type. When i use imview to view the image, I am getting a plain white image. If i convert it back to unsigned integer, then i am getting all values of my matrix as 255 and hence no image.
What do I do?? Are there some other functions that can be used??
Thanks
Abhi

 

[echo47]

matlab doubt!!!

Sounds like a scaling or offset problem. Examine the arrays after each step to find where things are going wrong. If you are still stuck, show us a small example code that demonstrates the problem.

 

[abhigopal]

matlab doubt!!!

Ok, Echo47
My input image is lenna.gif which is a 2565 X 256 matrix. At first, I did not realise tht it would cause problems. This is in the formed of Unsigned 8 bit integer (Uint8). Later, I added tht second line and it seemed to work fine.
I do some operations and end up with another matrix of the same order. Actually, I have to retrieve the image from this matrix. This matrix is understandably of the form double. I cant retireve and image with this by using imview('matrixname');

This is my problem

Thanks

Code

in1=imread('lenna.gif');
indou=double(in1);

 

[echo47]

matlab doubt!!!

My MATLAB says imview is obsolete and gives no documentation, but IIRC its grayscale values for double must be 0.0 through 1.0, so try this:

in1=imread('lenna.gif');
indou=double(in1);
imview(indou/255);

or convert indou back to uint8 before calling imview.

Please don't process Lenna too much. She's just fine the way she is.