error using webcam

i want to track redobjects,i have code for it and it detects redobjects,but wen i use cam to take picture i get an error

error is

Error using ==> end

Incorrect cell or structure reference involving "end".
Most likely cause is a reference to multiple elements of a cell or
structure followed by additional subscript or structure references.

Error in ==> getCameraInfo at 4
camera_id = camera_info.DeviceInfo.DeviceID(end);

the code for getCameraInfo is

function [camera_name, camera_id, resolution] = getCameraInfo(a)

camera_name = char(a.InstalledAdaptors(end));

camera_info = imaqhwinfo(camera_name);

camera_id = camera_info.DeviceInfo.DeviceID(end);

resolution = char(camera_info.DeviceInfo.SupportedFormats(end));

can anyone suggest please

Answer 1

[Walter Roberson]

camera_info or camera_info.DeviceInfo is a structure array with multiple elements, so either camera_info or camera_info.DeviceInfo represents multiple array values simultaneously. You then try to index in to a field in one of those arrays, but MATLAB does not allow that operation.

For example, if you had

A(1).id = 1:5;
A(2).id = 6:10;

then A.id(end) would try to refer to both A(1).id(end) and A(2).id(end) simultaneously... which isn't allowed.

You should use

size(camera_info)
arrayfun(@size,[camera_info.DeviceInfo],'Uniform',0)

to explore to see which is the structure array with multiple elements.

[FIR]

i did as u sai dbut i get error

the error is

Error in ==> getCameraInfo1 at 2

camera_name = char(a.InstalledAdaptors(end));

??? Output argument "camera_id" (and maybe others) not assigned during call to

"C:\Documents and Settings\User\Desktop\camera\getCameraInfo1.m>getCameraInfo1".

Answer 2

[Daniel Shub]

I am not sure, but following on from Walter ...

Are you sure you want

camera_info.DeviceInfo.DeviceID(end)

and not

camera_info(end).DeviceInfo.DeviceID

or

camera_info.DeviceInfo(end).DeviceID

or similarly for your comment to Walter. Instead of

a.InstalledAdaptors(end)

try

a(end).InstalledAdaptors

I am just guessing here. The output of whos or even better a description of the class and size of each object (and the nested objects) would make it easier to diagnose.