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Re: [Imgcif-l] High speed image compression
- To: The Crystallographic Binary File and its imgCIF application to image data <imgcif-l@iucr.org>
- Subject: Re: [Imgcif-l] High speed image compression
- From: "Herbert J. Bernstein" <yaya@bernstein-plus-sons.com>
- Date: Fri, 29 Jul 2011 06:53:54 -0400
- In-Reply-To: <4E327491.7050502@esrf.fr>
- References: <4E31AE8C.8040405@rayonix.com><CAMkkSyn+uC4VxZpaqAhQb=ENzJYEgj+N5CCs+bPt2-JS+S_otQ@mail.gmail.com><4E31E452.3050905@rayonix.com> <4E327491.7050502@esrf.fr>
I agree. On my Mac, the time also drops sharply with pre-allocation and [] instead of push_back. At 10:51 AM +0200 7/29/11, Jonathan WRIGHT wrote: >Dear Justin, > >Your code counts the time compressing, but not the time writing the >file, which is much longer for me. As it stands, you might gain a little >by adding "packed.reserve(size*2)" just before the call to compress (54 >to 38 ms here on vista64, 3.3 Ghz). That falls further (28 ms) if you >stop using "push_back" and instead allocate something which is >"certainly" large enough to start with and use packed[p++]=c. > >Cheers, > >Jon > >On 29/07/2011 00:36, Justin Anderson wrote: >> Thanks Nicholas. >> >> I only made a couple small changes to Graeme's code. 1: to load an image >> from a file and write to file and 2: to pass the data vectors by >> reference. The last change seems to have sped things up a little but >> it's still taking 110 - 130 ms to compress which is too slow. We are not >> as concerned with decompression speed as that will not need to occur in >> real-time. >> >> I put on our FTP here: >> ftp://ftp.rayonix.com/pub/del_in_30_days/byte_offset.tgz. >> >> Thanks, >> >> Justin >> >> On 7/28/11 2:06 PM, Nicholas Sauter wrote: >>> Justin, >>> >>> Just some comments based on our experience...first, I haven't tried the >>> compression extensively, just the decompression. But I've found Graeme's >>> decompression code to be significantly faster than the CBF library, first >>> because it is buffer-based instead of file-based, and also because it >>> hard-codes some assumptions about data depth. >>> >>> I'd be happy to examine this in more detail if there is some way to share >>> your code example... >>> >>> Nick >>> >>> On Thu, Jul 28, 2011 at 11:46 AM, Justin >>> Anderson<justin@rayonix.com>wrote: >>> >>>> Hello all, >>>> >>>> I have run Graeme's byte offset code on a 4k x 4k (2 byte depth) >>>> Gaussian >>>> noise image and found it to compress the image in around 150 ms (64-bit >>>> RHEL, Pentium D 3.46GHz). Using CBF library with byte offset >>>> compression, I >>>> find the compression takes around 125 ms. >>>> >>>> This will be too slow to keep up with our high speed CCD cameras. We are >>>> considering parallelizing the byte offset routine by operating on >>>> each line >>>> of the image individually. Note that this would mean that a given >>>> compressed image would be stored differently than via the whole image >>>> algorithm. >>>> >>>> Has anyone been thinking about this already or does anyone have any >>>> thoughts? >>>> >>>> Regards, >>>> >>>> Justin >>>> >>>> -- >>>> Justin Anderson >>>> Software Engineer >>>> Rayonix, LLC >>>> justin@rayonix.com >>>> 1880 Oak Ave. #120 >>>> Evanston, IL, USA 60201 >>>> PH:+1.847.869.1548 >>>> FX:+1.847.869.1587 >>>> >>>> >>>> _______________________________________________ >>>> imgcif-l mailing list >>>> imgcif-l@iucr.org >>>> http://scripts.iucr.org/mailman/listinfo/imgcif-l >>>> >>>> >>> >>> >> >> >> _______________________________________________ >> imgcif-l mailing list >> imgcif-l@iucr.org >> http://scripts.iucr.org/mailman/listinfo/imgcif-l >_______________________________________________ >imgcif-l mailing list >imgcif-l@iucr.org >http://scripts.iucr.org/mailman/listinfo/imgcif-l -- ===================================================== Herbert J. Bernstein, Professor of Computer Science Dowling College, Kramer Science Center, KSC 121 Idle Hour Blvd, Oakdale, NY, 11769 +1-631-244-3035 yaya@dowling.edu ===================================================== _______________________________________________ imgcif-l mailing list imgcif-l@iucr.org http://scripts.iucr.org/mailman/listinfo/imgcif-l
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