"My images are all upside down" • Hacker News Board

Re: "My images are all upside down"

#11

Post by gfosco » Tue, Jan 08, 2013, 2:54 PM UTC

jstanley wrote: post #8

What the hell? Why is there an orientation tag at all? Why isn't the picture just rotated by the device that takes it?

Why should it rotate, when it can use the standard method for notating the proper rotation? Your camera would be a lot slower if it had to rotate 16MP images between snaps.

Re: "My images are all upside down"

#12

Post by nextstep » Tue, Jan 08, 2013, 2:58 PM UTC

Speaking of iPhones, this blog is pretty much unreadable on Mobile Safari. I side scroll to see the text; the paragraph disappears behind the left sidebar.

Re: "My images are all upside down"

#13

Post by ianstallings » Tue, Jan 08, 2013, 3:04 PM UTC

This would be easier to fix in objective-c and a little custom camera wrapper application. I would expect a fix in a new OS release though. But if you need this little app let me know and I'll write it and put it on github.

Re: "My images are all upside down"

#14

Post by jonknee » Tue, Jan 08, 2013, 3:05 PM UTC

micampe wrote: post #10

jstanley wrote: post #8

What the hell? Why is there an orientation tag at all? Why isn't the picture just rotated by the device that takes it?

Because lossless rotation is fairly expensive computationally so digital cameras have been leaving that job to a computer.

In this case the camera is a computer though. A computer that knows its orientation.

Re: "My images are all upside down"

#15

Post by route3 » Tue, Jan 08, 2013, 3:09 PM UTC

During the holiday break I spent some time learning about EXIF data and subsequently released Exif.in[0], a simple HTTP API for viewing EXIF data inside images and requesting EXIF-stripped copies as well.

If you're a developer who needs to occasionally inspect EXIF data from user uploads, please check it out. Contact me if you have additional questions, I'm happy to help.

[0] http://exif.in

Re: "My images are all upside down"

#16

Post by jstanley » Tue, Jan 08, 2013, 3:10 PM UTC

micampe wrote: post #10

jstanley wrote: post #8

What the hell? Why is there an orientation tag at all? Why isn't the picture just rotated by the device that takes it?

Because lossless rotation is fairly expensive computationally so digital cameras have been leaving that job to a computer.

I was assuming the rotation tag only expressed axis-aligned rotation, in which case lossless rotation is not that expensive compared to taking the photo in the first place.

Re: "My images are all upside down"

#17

Post by smackfu » Tue, Jan 08, 2013, 3:10 PM UTC

gfosco wrote: post #11

jstanley wrote: post #8

What the hell? Why is there an orientation tag at all? Why isn't the picture just rotated by the device that takes it?

Why should it rotate, when it can use the standard method for notating the proper rotation? Your camera would be a lot slower if it had to rotate 16MP images between snaps.

OTOH, it has to rotate it for display on the screen, so it can't be that computationally bad.

Re: "My images are all upside down"

#18

Post by freehunter » Tue, Jan 08, 2013, 3:12 PM UTC

rem1313 wrote: post #5

What puzzles me is that Windows XP up to Windows 7 built-in picture viewer does not support proper orientation of iPhone photos with the original EXIF metadata in place. Picasa (on Windows) handles that perfectly, as well as (obviously) all apps in OS X. What the hell Microsoft? Is this a political thing or is there a valid technical reason?

I don't think it's either of those things. I had problems with Windows Phones and getting the orientation right in Picture Viewer as well. I don't think it's politics, I don't think it's a valid technical reason, I think it's just an oversight.

Re: "My images are all upside down"

#19

Post by smackfu » Tue, Jan 08, 2013, 3:16 PM UTC

jstanley wrote: post #8

What the hell? Why is there an orientation tag at all? Why isn't the picture just rotated by the device that takes it?

The theory is that you have the image off the sensor, and then you have metadata about the image in the EXIF fields. The debatable point is whether orientation should be treated as metadata or is inherent to the image data. On early digital cameras, this wasn't so debatable since adding an orientation sensor was a deluxe feature that really did just add another bit of data to the photo.

Re: "My images are all upside down"

#20

Post by CountHackulus » Tue, Jan 08, 2013, 3:18 PM UTC

jonknee wrote: post #14

micampe wrote: post #10

Earlier quoted context omitted.

Because lossless rotation is fairly expensive computationally so digital cameras have been leaving that job to a computer.

In this case the camera is a computer though. A computer that knows its orientation.

Not to mention that it's rotating by +-90 or 180 degrees, which is a whole lot faster than an arbitrary rotation.