Problem with image processing

[123BIOCOM]

I am trying to work with jpg and tiff image. With jpg image i am trying to localize dimension of some points.
i used folowing commands and errors are displayed as below:
(images are grayscale)

>> a = double(imread('C:\\wt003.jpg'));

>> H=double(imread('C:\\wt003.jpg'));
>> imagesc (H); figure(gcf)
imagesc (H); figure(gcf)
??? Error using ==> image
Error using ==> image
TrueColor CData contains element out of range 0.0 <= value <= 1.0.

Error in ==> imagesc at 18
hh = image(varargin{1},'CDataMapping','scaled');


>> w=bpass(A,1,11);
??? Function 'conv2' is not defined for values of class 'double' and attributes 'full 3d real'.

Error in ==> bpass at 65
g = conv2(res,gx,'valid');


Kindly reply soon. I really appreciate your help