2019.03.30 14:15 "Re: [Tiff] combining TIFF images, not multi-page", by Kemp Watson
TIFF of several hundred gigabytes are actually quite common, and are viewable in real time. We have many thousands of them, from hundreds of customers in the medical imaging field. They are not cumbersome at all when the system workflow is designed around their unique requirements.
As it happens, putting them in a single file is the _only_ thing that makes sense, otherwise they are far too cumbersome to move around and ensure data integrity. We have nothing but headaches with fetching individual tiles stored on a server, much better to extract the tile data from a solid file. The client knows no difference.
W. Kemp Watson
+1 (416) 970-7284
Objective Pathology Services Limited
13629 Fallbrook Trail, Halton Hills
Ontario, Canada L7G 4S8
From: Tiff <email@example.com> on behalf of Paavo Helde <firstname.lastname@example.org>
May I ask what is your goal when creating a single TIFF image several hundred gigabytes in size? It would be impossible to view it with common TIFF viewers and handling so large files is very cumbersome anyway.
The only use case I can imagine for such a thing would be to provide the maximum zoom-in resolution in a pyramidal TIFF, but even in this case it would not make much sense to put it all in a single file. Cf Google Earth or Google Maps, you don't need to first download terabytes of data to use it on your computer, the zoom-in tiles are fetched separately over the network when needed.
On 30.03.2019 14:44, Paul Hemmer wrote:
As to the "low RAM footprint way" - in fact I am hoping to use the hard-drive instead of RAM. This is why I have a folder full of small partial images in the first place.
Even with a pyramidal representation, if I'm talking about a final image that may be several hundred gigabytes (or larger) in size, I could never assemble it all in memory in order to write the bottom layer of that pyramid. Can each resolution level be written in "tile by tile" or even line by line? Does this require a different API (like the ImageMagick API?) I assume as well that BigTIFF can be a tiled pyramid?
From: Bob Friesenhahn <email@example.com><mailto:firstname.lastname@example.org>
Sent: Friday, March 29, 2019 7:02 PM
To: Paul Hemmer
Cc: Tiff List
Subject: Re: [Tiff] combining TIFF images, not multi-page
On Fri, 29 Mar 2019, Paul Hemmer wrote:
> Hi, thanks for the reply!
> Do tiled TIFFs open and display as a single image? Do the tiles all
> have to be the same size? My images are broken into full-height
> "columns" of varying widths, that I want to concatenate all together
> into one image in a low-RAM footprint way.
Tiled TIFF does typically "open and display as a single image" but
this is a function of the reader. The reader might choose just to
display one tile, or the image portion corresponding to several tiles.
The tile size is fixed within a given TIFF image.
As has been subsquently mentioned, ImageMagick and GraphicsMagick
provide 'montage' functionality which can paste images together as you
describe, but they do not do so in a "low-RAM footprint way", unless
you are willing to use your hard drive in place of RAM.
If you are dealing with very large images, then it is common to use
tiled tiff with multiple resolutions of the same image so that the
viewer than see a zoomed-out image as well as zoom in to just part of