what is the difference btwn conv2 and filter2 in matlab?

Hi,

I am trying to apply 2D FIR filters to an image. wat is the difference
btwn using conv2 and filter2?

When i use conv2, I can obtain an image of the same size as the
original image, but if i were to use filter2, the result is only a few
pixels.

another question is upon reading in an image using imread, do i need to
convert to ycbcr format before i perform the conv2 or filter2?

Urgent help is needed and any advice given is much appreciated.

Best Regards,
fulltime

fulltime wrote:
> Hi,
> 
> I am trying to apply 2D FIR filters to an image. wat is the difference
> btwn using conv2 and filter2?
> 
> When i use conv2, I can obtain an image of the same size as the
> original image, but if i were to use filter2, the result is only a few
> pixels.
> 
> another question is upon reading in an image using imread, do i need to
> convert to ycbcr format before i perform the conv2 or filter2?
> 
> Urgent help is needed and any advice given is much appreciated.
> 
> Best Regards,
> fulltime
> 

I don't use Matlab often anymore, but I remember using the 1-D 
equivalent functions, i.e. filter and conv.  I believe the difference 
comes down to the number of samples in the output.  For example let's 
say you have input x and impulse response h to give you an output y 
(with respective lengths len_x, len_h, len_y).  When using the filter 
function len_y will be len_x, but when using the conv function then 
len_y will equal len_x+len_h-1.

Brad