Change DPI while keeping resolution

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fmw42
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Re: Change DPI while keeping resolution

Post by fmw42 » 2019-09-16T16:45:27-07:00

I have never used it, but I think you have to install it as a delegate, possible in place of libtiff. However, check the libtiff library and see if it is included in libtiff. You may need TIFF64, if so, then try

Code: Select all

magick in.exr -define quantum:format=floating-point TIFF64:out.tif
Searching Google I see these:

https://www.imagemagick.org/discourse-s ... 548#p88311
http://www.multipole.org/discourse-serv ... 362#p75899

https://www.imagemagick.org/discourse-s ... hp?t=32297

This link seems to imply that libtiff supports TIFF64
https://www.imagemagick.org/discourse-s ... hp?t=21548

snibgo
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Re: Change DPI while keeping resolution

Post by snibgo » 2019-09-16T17:01:28-07:00

Jimbo wrote:And, if so, is there any flag that I need in order to create TIFF64 as opposed to TIFF?
Use the prefix "TIFF64:" on the output.
snibgo's IM pages: im.snibgo.com

Jimbo
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Re: Change DPI while keeping resolution

Post by Jimbo » 2019-09-16T17:25:27-07:00

Thanks, fmw42 and snibgo!

Testing TIFF64 now, and yes, it is supported in libtiff 4.0.10_1 (which I am using), and I believe, supported since libtiff 3.8.2.

UPDATE:
50000 x 28125 @ dpi90 tiff file = 16.88 Gbytes

converted from .PSB file with this call:
magick in.psb -define quantum:"format=floating-point TIFF64:out.tif

And the original PSB file was a 32bit floating point image with colors over 1 (up to 1.6414 RGB values)
and the resulting TIFF64 (eg. BigTIFF) image kept all of that with it.

UPDATE:
FYI: Photoshop reads the BigTIFF format about 4 times faster that it's own .PSB Large Format Filetype.

SWEET! Thank you, one and all (magick, fmw42 and snibgo) for helping me get to this solution.

Cheers!
- Jimbo

PS- I will be posting what I know about the psd and psb issues concerning HDRI imagery in the Developers Forum. - J

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