jpegs - is there a difference apple vs pc?

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jpegs - is there a difference apple vs pc?

Postby J. St.C. Patrick » Thu Sep 17, 2015 8:44 pm

I've noticed over the past few months that the photo manipulation program I'm using keeps crashing whenever I do basic things to images imported from an iphone. - cropping or changing image size.
I have no trouble using this program to edit pictures taken on my sony camera, my older casio, pictures i get from other manufacturers' phones, or even pictures I've downloaded.

So is there a difference between apple jpegs and other jpegs?
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Re: jpegs - is there a difference apple vs pc?

Postby Ellen Kuhfeld » Thu Sep 17, 2015 8:55 pm

When I've had to deal with Apple files, it was my impression that "a" Apple file was really two files. You might try bringing your iPhone picture into that program, then save it right away; I suspect the saved file would behave better.
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Re: jpegs - is there a difference apple vs pc?

Postby Té Rowan » Fri Sep 18, 2015 7:39 am

It tends to be so: A data file and a resource file. The resource file (or resource fork) stores some system-specific stuff and is often useless outside of an Apple system.
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Re: jpegs - is there a difference apple vs pc?

Postby J. St.C. Patrick » Sat Sep 19, 2015 4:34 pm

Ellen Kuhfeld wrote:When I've had to deal with Apple files, it was my impression that "a" Apple file was really two files. You might try bringing your iPhone picture into that program, then save it right away; I suspect the saved file would behave better.


Thanks for the suggestion. It works. sort of.

If i save the image, but keep it open - the program crashes.
If i save the image in a new place - the program crashes - and the saved version can't be opened -corrupted file
If i save the image in a new place - close and reopen the image, the program crashes - and the saved version can't be opened -corrupted file
if I save the image with a new name and keep it open - the program crashes - and the saved version can't be opened -corrupted file
If I save the image with a new name, close the image then open it again - it seems to be okay.
However if I open a second iphone image to copy from it, the program crashes before I can save it.

So apparently i'll have to save the images with new names - closing after each save, before I can do anything with them. At least in the program I'm using.

Té Rowan wrote:It tends to be so: A data file and a resource file. The resource file (or resource fork) stores some system-specific stuff and is often useless outside of an Apple system.

So it's the resource fork that's causing the crashes?
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Re: jpegs - is there a difference apple vs pc?

Postby Té Rowan » Sat Sep 19, 2015 6:11 pm

Haven’t got the foggiest, but if I recall correctly, it is usually stored separate fom the data fork — in an Extended Attributes directory field, I think.

Aside: If you are using a Windows machine, you might want to try Irfanview as an interim stage (view and resave with that). It can do some basic image manipulation, too.
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Re: jpegs - is there a difference apple vs pc?

Postby Spica75 » Sat Sep 19, 2015 10:15 pm

Try find a converter program that fixes it automatically?

( not dealing at all with anything "apple" i have zero direct knowledge here i´m afraid )
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Re: jpegs - is there a difference apple vs pc?

Postby Munchkin » Sun Sep 20, 2015 7:21 am

I seem to recall that various versions of iOS store some custom fields in the JPEG header block. If it's written properly, then your program would have no problem reading the files, but it's entirely possible that your program cannot cope with the custom fields in the header and is corrupting its own data somewhere else in memory when reading the header, leading it to crash when it tries to use the data that's been corrupted.

Unfortunately, the sad fact is that the majority of image manipulation programs are not written to properly handle unexpected data (even Adobe software hits this flaw on a few file formats, at least up to Photoshop CS5, I've not tried the more recent versions). This is often because they are written to cope only with certain versions of image files, rather than written correctly to the file format specifications, so that they are forward compatible with more recent versions (they're just hard-coded to expect certain data instead). Therefore more recent image creation software can write out versions of files that cannot be handled correctly by these older programs.

As already mentioned, your best bet would be to find some other software that can import or read/write the files to somewhere else in a version of the file more compatible with your preferred manipulation program. If you can't find one, you may want to consider finding a program that can read them, and write them out into a different file format, like BMP, TGA or PNG, as an intermediate file (you can always save back out into JPG from your preferred program once opened if desired).
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