Mars Explorer Rover pictures not shown full-size in Preview

[ebow]

I've been regularly following the progress of the Spirit rover on Mars, checking for the latest pictures, etc. When there's a particularly good picture, I'll download it... but the largest ones are not displaying properly in Preview (I'm running 10.3.2)!

For example, in this press release there's a link to the large 12MB version of the 360 degree color panorama. B!tchin' picture (direct link). When I download that large image and load it in Preview, it (eventually) loads and claims that at 100%, the image height is about 1/3 of my 15" iMac screen's height. Nonsense--it's over 1300 pixels tall. Even when I resized it down to 768 pixels tall using Graphic Converter (which displays it properly), Preview gets it wrong.

Has anyone seen this sort of thing, or know what is going on?

addendum: I seem to have found a discussion about the same thing (though with an older version of Preview) from nearly two years ago.

 

[yoman]

what seems to be the problem

Are you having problems zooming into the image to see it full size

or

are you upset that preview automatically tries to fit the whole image within your screen including height and width.

???

 

[arn]

yeah, preview auto-sizes to screen. try hitting the zoom button

arn

 

[Nermal]

Press Cmd-0 and Preview should stop auto-resizing it.

 

[ebow]

Re: what seems to be the problem

Originally posted by yoman
Are you having problems zooming into the image to see it full size

or

are you upset that preview automatically tries to fit the whole image within your screen including height and width.

???

Nope, neither. The problem is that I have a file that's known to be 768 pixels tall (I modified it to that height using GraphicConverter) yet viewed at 100% it only takes up about 1/2 the height of my screen (running at 1024x768). When I click the Actual Size button, it zooms to 72%.

I believe the problem is due to the DPI of this particular image file. Getting info in Preview shows it to be 6196x768 pixels at 100x100 DPI. So I think it's being rather "strict" about how it renders, basing the display size on both pixels and DPI. Thing is, neither GraphicConverter nor Safari appear to use DPI to affect how images are displayed, and it seems neither does the app that JPL/NASA is using.

So... is this a case of right and wrong? More correct and less correct? Apple doing a more technically correct thing while the rest of the world does something slightly different?

 

[ebow]

To make things even more confusing, a full-screen screenshot (using command-shift-3 on my 1024x768 screen) gives a PDF file that GraphicConverter reports to be 4266x3200 at 300x300 DPI. And of course Preview shows it true to form at Actual Size/100%. I'm sure this all makes sense but... I'm heading to bed.