get an image from pcapng file by c# program

I have network stream that i sniffing by wireshak.

for ex I sniff cats image from google images, by wireshark.

save the sniff in pcapng file, it save in binary file . now I want to show the image one by one

when get the stream from FF D8 to FF D9 the image seem to be less segments then the original image

who can I get the mising segments