Re: EXIF support in PNG

John Bowler <[email protected]>
Newsgroups gmane.comp.graphics.png.general
Message-ID <CAP7U39_W9t=DADGpsF+Gouna8jFCrH5W7R+-Taz66-2TEvyP-A@mail.gmail.com>
On Thu, Jan 5, 2017 at 2:05 PM, Willem van Schaik <[email protected]> wrote:
>
> oops, copied from the wrong line, should be 000072b0
>
> the SOI is two bytes, so then the last bytes become "d4 cb 71 a3"

Hum; I expect to see 0xff after the end, that 0xff should be at
0x0004+0x0x72B5 = 0x72B9, that's not the first 0xff:

> 000072b0  37 71 f9 d4 cb 71 a3 ff  d9 [ff db] 00 84 00 02 01

FFD9 is EOI, end of image, and is the last thing in the JPEG
FFDB is DQT and happens in the middle of the JPEG

A valid image needs an SOFn marker, 0xFFCn and ends with FFD9 (EOI)

It may be that the FFD9 is specified by EXIF, or it may just be a coincidence.

John Bowler

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