EXIF orientation info in PNGs isn't used for image-orientation: from-image

Orientation in EXIF was an ugly hack and we're living with its fallout today.

Cameras should have just rotated the actual image pixels when saving, instead of cheating. If that's too slow, implement it in hardware, or schedule a deferred process and don't let the images be exported until that's done.

Eh, the coordinate frame can really be anything. It's important to disambiguate what is really meant. The convention in images is that images are +X-Y, but for certain applications, the PNG may represent data that is +X+Y, or mirrored -X+Y, landscape, or portrait. Is the coordinate system the camera coordinates or the world coordinates?

It's true that automatic handling of all input images is difficult, but imo it's important to document.

An example I recently encountered is that in neurological imaging, the axes are patient's right, anterior, superior whereas in radiology they are patient's left, anterior superior. Tricky to get right...

http://www.grahamwideman.com/gw/brain/orientation/orientterm...