determining the pixel aspect ratio of a TIFF

[easyhtrees]

Hi there, this is a little out of my domain so please bear with me. I have a TIFF image coming out of an in house application and the issue seems to be that, while the size of the image is correct (1024 x 768), the pixel aspect ratio is not. How do I measure this using ImageMagick for Windows? I had heard this tool could do it, but I am not sure how. Thanks in advance.

[fmw42]

What do you mean by pixel aspect ratio? Do you mean the width/height ratio of the image where the width and height are in pixels? If so, then

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convert image.tiff -format "%[fx:w/h]\n" info:

If on IM 7, then use magick rather than convert.

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http://www.imagemagick.org/script/comma ... essing.php
http://www.imagemagick.org/Usage/reference.html
http://www.imagemagick.org/Usage/
https://github.com/ImageMagick/usage-markdown

[easyhtrees]

Thanks for the response. My understanding is that 'Pixel Aspect Ratio' refers to the ratio of the pixel's width to its height. I should clarify that the above doesn't give me that information.

[snibgo]

How do I measure this using ImageMagick for Windows?

Please link to a sample TIFF with non-unity pixel aspect ratio. Then we can try a few things.

[easyhtrees]

Here is an upload: https://imgur.com/hPq53nZ

[snibgo]

You asked about TIFF, but the link is to a PNG?

"hPq53nZ - Imgur.png" seems to have square pixels.

But I've remembered how pixel aspect ratio is recorded: in the density. Square pixels (the normal situation) have equal densities in x and y. Non-square have unequal densities.

[easyhtrees]

Is there a better image hosting site I can use? It's TIFF on disk, I don't know how it ended up being a PNG.

[snibgo]

Don't use an image hosting website. They often convert the image to something else for display. Some allow the original to be downloaded, but some discard the original.

Instead, use a file hosting site. dropbox.com seems to work fine.

But you can do the test yourself:

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magick identify -verbose yourfile.tiff

Look for a line like "Resolution: 200x100"

[easyhtrees]

I just tried that and sure enough, the AR is not 1. Thanks, I'll use this method for now.

[GeeMack]

I just tried that and sure enough, the AR is not 1. Thanks, I'll use this method for now.

This should give you both X and Y resolutions...

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magick input.tif -format "%[fx:resolution.x] %[fx:resolution.y]" info:

You can use those FX expressions in a calculation to get the aspect...

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magick input.tif -format "%[fx:resolution.x/resolution.y]" info:

If you're using IM6 use "convert" instead of "magick".