Sequence and merge jpeg images using Python?
Not exactly knowing what you mean my sequence - ImageMagick, esp. its 'montage' is probably the tool you need. IM has python interface, too, altough I have never used it. 
EDIT: As after your edit I do not get the point of this any more, I cannot recommend anything, either. :(
im doing a project as part of academic programme.Im doing this in linux platform.here i wanted to create a application which retrieve some information from some pdf files .for eg i have  pdfs of subject2,subject1,in both the whole pdf is divided in to 4 modules and i want to get the data of module 1 from pdf..for this purpose my tutor told me to use pdftohtml application and convert pdf files to html and jpeg images.now i want to create a Python script which will combine the pages(which have been coverted in to jpeg images) under module 1 and merge it into a single file and then i will convert it back to pdf . how can i do this?.if anyone can  provide any such python script which have done any functions similar to this then it will be very helpful.
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thanks in advance