Re: Importing a large image...

*To*: mathgroup at smc.vnet.net*Subject*: [mg98614] Re: [mg98523] Importing a large image...*From*: peter <plindsay.0 at gmail.com>*Date*: Tue, 14 Apr 2009 06:17:32 -0400 (EDT)*References*: <200904110758.DAA22371@smc.vnet.net>

hi David I have a solution I think. I used a sample TIFF of ~700MB. I note you use a Mac, so that makes it easy - I opened it in GraphicConverter, a free app [ http://www.lemkesoft.com/ ] and saved it as a [ lossless ] PNG but also used the save option to Split the file into 4 X 3 smaller constituent files. Each of these files [ ~20MB ] is then easily imported into Mathematica by something like: a=Import["Desktop/tiff-2a-03-03.png"] I'm sure the http://www.imagemagick.org/ utility [ which is available free on the mac and I think via mactex installation ] can do a similar trick. Conversion to PNG is probably not necessary but it seemed like a good idea at the time ;) I hope this helps Peter 2009/4/11 David Reiss <dbreiss at gmail.com>: > So, my fellow denizens of the group. > > I have a very large TIFF image--roughly 700MB in size. > > Its dimension are 43201 by 15601. It is single color with a bit depth > of 8. > > Mathematica is unable to Import this file on my 6 GM RAM powerbook > without maxing out the memory. > > I actually do not need to read in the whole file: I'd be happen with > being able to break the file into a number of smaller TIFFs which tile > it completely and then process each on independently (I am needing to > act on the data in various ways to yield a processed result for > further analysis down the line). This is all for a larger project > for a consulting client of mine. > > Any suggestions for how to programmatically carve up the image without > having to completely read it in first? I am looking for quick > solutions rather than ones that require a lot of programming. Either > it can be done pretty simply, or (more likely) Mathematica chokes on > these very large files. > > (Photoshop, on the other hand, does not choke on it at all, nor do > some other programs that are optimized for image analysis such as ENVI > (http://www.ittvis.com/ProductServices/ENVI.aspx): but I don't want to > work with these... nor do I have them....) > > Of course this leads to a suggestion for the Import function: to allow > reading in only a part of an image at a time. > > Feel free to respond to the list, but also CC me on the replies so > that I get them sooner than the usual turnaround. > > Thanks! > > --David > > -- Peter Lindsay