Embedding JPG in PDF

Question

I've added some XMP data to JPG files in order to track the files through the production process. As a test of the process I modified a simple PS file from the Adobe reference (shown below) and processed it using distiller 6 to create a PDF.
If the image is not resampled and doesn't have a clipping path then distiller just embeds the original JPG and the XMP data is preserved within the embedded JPG. However if the image has a clipping path or is downsampled then distiller seems to throw the XMP away (even if the option 'Save original JPG in file if possible' is selected)
Can anyone tell me what I am doing wrong - it would seem to defeat the purpose of XMP as a way to track files if distiller just removes the information when it creates a PDF.
Thanks
PS file being processed (where SX.JPG contains XMP data)
<</PageSize [ 3000 3000 ] >> setpagedevice
newpath
200 50 moveto 400 0 rlineto 0 600 rlineto -200 0 rlineto closepath clip
/infilename (C:\\Test\\sx.jpg) def % filename
/w 762 def
/h 1647 def
% read a JPEG image
/DeviceRGB setcolorspace % pick color model
200 100 translate % set page position
w h scale % magnify unit square
/infile infilename (r) file def % establish input read file
/Data {infile /DCTDecode filter} def % define a data source
<< % start image dicationary
/ImageType 1 % always one
/Width w % JPEG width in pixels
/Height h % JPEG height in pixels
/ImageMatrix [w 0 0 h neg 0 h ] % see comments below
/DataSource Data % proc to get filtered JPEG
/BitsPerComponent 8 % color resolution
/Decode [0 1 0 1 0 1 ] % per red book 4.10
>>
image % call the image operator
showpage

Answer 1

Hi Gunar,
I appreciate the reply, its is good to be able to see that this is not something I'm missing but actually how it is intended to work.
To take it a bit further though I would like to be able to track a image (JPG or other format) through the production workflow and then at the end distill the final page.
All the PDF pages produced would then be able to be analysed to see what images were used (useful for tracking library image usage or even paying for copyrighted images).
XMP seemed like a good option but if a image is deep etched or cropped(and therefore resampled by distiller) then the XMP is discarded and the image can no longer be tracked. An option to preserve metadata would be very useful, is there any way to do that (or is it something that could be requested for the future)?
Thanks