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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: Jonathan WRIGHT <wright@esrf.fr>
- Date: Fri, 29 Jul 2011 10:51:29 +0200
- In-Reply-To: <4E31E452.3050905@rayonix.com>
- Organization: ESRF
- References: <4E31AE8C.8040405@rayonix.com><CAMkkSyn+uC4VxZpaqAhQb=ENzJYEgj+N5CCs+bPt2-JS+S_otQ@mail.gmail.com><4E31E452.3050905@rayonix.com>
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
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