Reading JPEG Headers - Programmers Heaven

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Reading JPEG Headers

I am writing a steganography program and I need to figure out where the JPEG header ends and where the image data begins. I know that JPEG's don't officially have a formal header apparently, which makes them a bit more difficult to work with than bitmaps, since their headers aren't a fixed size like bitmap files. So far, I have trashed 3 jpegs with no success. If someone has source code on a JPEG header parser, or just the right jpeg header marker to look for and its length bytes, it would be a great help.

Thanks in advance,
Russell

Comments

  • DjSpiritDjSpirit Posts: 371Member
    : I am writing a steganography program and I need to figure out where the JPEG header ends and where the image data begins. I know that JPEG's don't officially have a formal header apparently, which makes them a bit more difficult to work with than bitmaps, since their headers aren't a fixed size like bitmap files. So far, I have trashed 3 jpegs with no success. If someone has source code on a JPEG header parser, or just the right jpeg header marker to look for and its length bytes, it would be a great help.
    :
    : Thanks in advance,
    : Russell
    :
    [grey]Can't you just LoadPicture the image into a hidden picturebox and Point(x,y) the data you need?

    There is a faster way than Point(x, y) to get the data out, but I don't seem to get the code for getting the pointer to the data area of a picturebox to work correctly.

    DjSpirit, just a thought[/grey]
  • Russell MooreRussell Moore Posts: 7Member
    : : I am writing a steganography program and I need to figure out where the JPEG header ends and where the image data begins. I know that JPEG's don't officially have a formal header apparently, which makes them a bit more difficult to work with than bitmaps, since their headers aren't a fixed size like bitmap files. So far, I have trashed 3 jpegs with no success. If someone has source code on a JPEG header parser, or just the right jpeg header marker to look for and its length bytes, it would be a great help.
    : :
    : : Thanks in advance,
    : : Russell
    : :
    : [grey]Can't you just LoadPicture the image into a hidden picturebox and Point(x,y) the data you need?
    :
    : There is a faster way than Point(x, y) to get the data out, but I don't seem to get the code for getting the pointer to the data area of a picturebox to work correctly.
    :
    : DjSpirit, just a thought[/grey]
    :
    That might work, but I also need to know where it begins in the file so I can write over those bytes in the image.
  • Ray0925Ray0925 Posts: 1Member
    : I am writing a steganography program and I need to figure out where
    : the JPEG header ends and where the image data begins. I know that
    : JPEG's don't officially have a formal header apparently, which makes
    : them a bit more difficult to work with than bitmaps, since their
    : headers aren't a fixed size like bitmap files. So far, I have
    : trashed 3 jpegs with no success. If someone has source code on a
    : JPEG header parser, or just the right jpeg header marker to look for
    : and its length bytes, it would be a great help.
    :
    : Thanks in advance,
    : Russell
    :
    I'm a student, iam working with an image processing program, dealing with bitmap and jpeg files. and i am also stuck at this point, do you have any solution now?
    i need to know how big is the JPEG(or JFIF) header?
    how to take the width and height out?
    when is the header finish and where the data start.

    many thanks,
    Ray
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