[Gambas-user] Is exif Orientation obtainable without any exif libs/commands?

[Bruce Steers]

On Mon, 5 Dec 2022 at 16:20, Rolf-Werner Eilert <rwe-sse at osnanet.de> wrote:

> Am 05.12.22 um 17:06 schrieb Bruce Steers:
> > So i've found exiftool is a tool to easily retrieve Orientation flag
> > from an image but it's not on all systems, not by default at least.
> >
> > Was wondering if anyone has a method to retrieve exif flags from an
> > image or the Orientation one at least?
> >
> > I found rotating and saving an image back to file removed it's
> > Orientation flag so that's cool.
> >
> > But I also found that to save a similar size file back i needed an
> > instruction like...
> > hPicture.Save(sPath, 92)
> >
> > I had to play with the quality value and found 92 about the right value
> > for a similar size file.
> > Wondered if there was a better way to save the image back with identical
> > file size (i assume a rotated image to be the same mass/size)
> >
> > Ultimately I'm looking to spin my images round to be correct way up with
> > zero quality change.
> >
> > The only piece of the puzzle gambas seems to lack is detecting the exif
> > Orientation flag.
> > Something in my mind suspects gambas Read could possibly be able to get
> > the data from the files?
> >
> > Respects
> > BruceS
> >
> >
> >
> > ----[ http://gambaswiki.org/wiki/doc/netiquette ]----
>
> Without looking in detail, but it should be in different positions
> depending on the file format. So for instance you would have to know
> where and how it is saved in a jpg file, open the file in binary mode,
> and jump to the information. The same with other file formats.
>
> Or did I get you wrong?
>
> Regards
> Rolf
>

Yes that's what I'm "suspecting" may be possible.
Just wondering if anyone has tried and failed, or tried and succeeded ?

looks like it's possible. I found this page...
https://gist.github.com/yepitschunked/9d2e73d9228f5a0b300d75babe2c3796
Has something i may be able to convert.
And plenty to study
https://www.media.mit.edu/pia/Research/deepview/exif.html

Just hoping someone else might have already looked into it and have some
working or unfinished code or just information they might share on the
topic before i have to start at square 1.

Respects
BruceS
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