BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Security camera image storage question.          BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc View previous topic :: View next topic   Author Message Dodgy Guest Posted: Thu Sep 01, 2005 1:06 pm    Post subject: Security camera image storage question. Hi all, I've got a blank and white low light security camera hooked up to a WinTV card and I'm happily capping images every second onto the hard drive. I'm using the EAVCap component, and it works fine. I was originally saving the images off as BMP, but at over a meg a file I was going to run out of hard drive before I'd capped a day. My plan was to hold a 7 day loop of images, so I now save them off as greyscale jpeg with 75% quality and that produces images of about 40k, which will just about squeeze 7 days onto the hard drive space I have. I'm storing the images in a directory structure as follows c:capsday_numberhourminsec.jpg The day number rotates from 1 to 7. Anyway, that's all well and good except if something happens I have to spend ages trawling through images to find it. So what I want to do now, to reduce disk storage and aid detection, is to do some comparison between the image I just capped, and the image I capped a second before, and only if I have enough of a difference, write the image file to the disk. I've got the last and next images on the screen in two Timage components, but I need a fast way to compare and decide. I'm capping at 1 a second, and the machine isn't anything amazing (550Mhz Pentium 3, 256meg ram, win2k pro). So can anyone offer any suggestions on how to calculate a difference level between 2 images so I can check this against a threshold? Cheers Dodgy. -- MUSHROOMS ARE THE OPIATE OF THE MOOSES Back to top Maarten Wiltink Guest Posted: Thu Sep 01, 2005 2:29 pm    Post subject: Re: Security camera image storage question. "Dodgy" <Dodgy (AT) earth (DOT) planet.universe> wrote Quote: I've got a blank and white low light security camera hooked up to a WinTV card and I'm happily capping images every second onto the hard drive. [...] Anyway, that's all well and good except if something happens I have to spend ages trawling through images to find it. Just play them at 30 or 50 fps. When you hit the button, replay the last second at 5 fps and pause. I think that a one-second interval is shorter than strictly necessary. There's nothing actually wrong with capturing that many images, but perhaps you could skip two or three for every frame you display, or blend a few consecutive images together. That's assuming this is a stationary camera. Groetjes, Maarten Wiltink Back to top Tom de Neef Guest Posted: Thu Sep 01, 2005 2:41 pm    Post subject: Re: Security camera image storage question. "Dodgy" <Dodgy (AT) earth (DOT) planet.universe> schreef in bericht news:2fudh1tue1jhpg7ch9gbn66jem5dnf3fvc (AT) 4ax (DOT) com... Quote: .... I've got the last and next images on the screen in two Timage components, but I need a fast way to compare and decide. I'm capping at 1 a second, and the machine isn't anything amazing (550Mhz Pentium 3, 256meg ram, win2k pro). So can anyone offer any suggestions on how to calculate a difference level between 2 images so I can check this against a threshold? For a bitmap your differential criterium is related to sum(abs(difference)), where you sum over all pixels and interpret them as integers. With jpeg this may also work, you'll have to try. Beware: even a stationary camera may vibrate a bit (wind, etc). An image that is displaced by one bit may result in quite a big differential. It may also help to cut from the image the parts that you're not interested in (like anything above 2 meters). I wonder if google's Picasa could help you with an overview of what you've captured. Tom Back to top Dodgy Guest Posted: Thu Sep 01, 2005 3:11 pm    Post subject: Re: Security camera image storage question. On Thu, 1 Sep 2005 16:41:04 +0200, "Tom de Neef" <tdeneef (AT) qolor (DOT) nl> waffled on about something: Quote: "Dodgy" <Dodgy (AT) earth (DOT) planet.universe> schreef in bericht news:2fudh1tue1jhpg7ch9gbn66jem5dnf3fvc (AT) 4ax (DOT) com... ... I've got the last and next images on the screen in two Timage components, but I need a fast way to compare and decide. I'm capping at 1 a second, and the machine isn't anything amazing (550Mhz Pentium 3, 256meg ram, win2k pro). So can anyone offer any suggestions on how to calculate a difference level between 2 images so I can check this against a threshold? For a bitmap your differential criterium is related to sum(abs(difference)), where you sum over all pixels and interpret them as integers. With jpeg this may also work, you'll have to try. I'm planning on putting this into the capping app, so the check can be done against the bitmaps before any chance of random jpeg artifacts can have an effect. Is there a quick way of comparing two 768x576 pixel images, creating some kind of numerical amount of change value and be able to keep up with the capture rate? Quote: Beware: even a stationary camera may vibrate a bit (wind, etc). An image that is displaced by one bit may result in quite a big differential. I don't mind a few false triggers, it's not going to be triggering an alarm or anything, it's purely recording. Even a 10:1 false to real movement trigger would be fine, at the moment I'm getting 3600 images an hour, with all but 20 being a view of a closed door! Quote: It may also help to cut from the image the parts that you're not interested in (like anything above 2 meters). I wonder if google's Picasa could help you with an overview of what you've captured. I really want to try and remove the redundant frames at source, as opposed to finding a faster way to scroll through them. Hard drive space is going to be an issue, and when this is fully up and running it will be pushing the images down the VPN across to our co-location site. At which point the bandwidth it uses will become an issue (well for the accountant anyway!). Dodgy. -- MUSHROOMS ARE THE OPIATE OF THE MOOSES Back to top Dodgy Guest Posted: Thu Sep 01, 2005 3:18 pm    Post subject: Re: Security camera image storage question. On Thu, 1 Sep 2005 16:29:23 +0200, "Maarten Wiltink" <maarten (AT) kittensandcats (DOT) net> waffled on about something: Quote: "Dodgy" <Dodgy (AT) earth (DOT) planet.universe> wrote in message news:2fudh1tue1jhpg7ch9gbn66jem5dnf3fvc (AT) 4ax (DOT) com... I've got a blank and white low light security camera hooked up to a WinTV card and I'm happily capping images every second onto the hard drive. [...] Anyway, that's all well and good except if something happens I have to spend ages trawling through images to find it. Just play them at 30 or 50 fps. When you hit the button, replay the last second at 5 fps and pause. I think that a one-second interval is shorter than strictly necessary. There's nothing actually wrong with capturing that many images, but perhaps you could skip two or three for every frame you display, or blend a few consecutive images together. That's assuming this is a stationary camera. Groetjes, Maarten Wiltink Hi Maarten, Not a bad idea, but I'd really like to automatically remove as much redundant footage as possible at source. At the moment I'm capping to a local harddrive, but shortly I'll be capping across our VPN to the co-location site. (Not much point having a security camera if the buggers can break in and steal the machine with all the images on it!). At that point although one 40k jpeg a second isn't going to bother the VPN bandwidth, the company accountant will come and moan at me as we have an allocated traffic volume per month with the co-location host company, and that level of constant data is pretty much going to use it all up. Then we'll start incurring burst traffic charges. Yes it is a stationary camera, it looks at a door. I tried dropping the capture rate, but found 1 a second is the best minimum that guarantees a good mug shot of anyone coming through the door. Dodgy. Dodgy. -- MUSHROOMS ARE THE OPIATE OF THE MOOSES Back to top Tom de Neef Guest Posted: Thu Sep 01, 2005 3:34 pm    Post subject: Re: Security camera image storage question. Quote: For a bitmap your differential criterium is related to sum(abs(difference)), where you sum over all pixels and interpret them as integers. With jpeg this may also work, you'll have to try. I'm planning on putting this into the capping app, so the check can be done against the bitmaps before any chance of random jpeg artifacts can have an effect. Is there a quick way of comparing two 768x576 pixel images, creating some kind of numerical amount of change value and be able to keep up with the capture rate? If it is in a Tbitmap, use scanline: (P1,P2 : PbyteArray; delta : integer;) delta:=0; for y := 0 to BitMap1.Height -1 do begin P1 := BitMap1.ScanLine[y]; P2 := BitMap2.ScanLine[y]; for x := 0 to BitMap1.Width -1 do inc(delta,abs(P1[x]-P2[x])) end; If it takes too long, compare every other 10th line or so. Tom Back to top Nicholas Sherlock Guest Posted: Thu Sep 01, 2005 7:50 pm    Post subject: Re: Security camera image storage question. Dodgy wrote: Quote: So can anyone offer any suggestions on how to calculate a difference level between 2 images so I can check this against a threshold? Take a look at Graphics32 http://www.g32.org. I never leave home without it . It's a really fast graphic library that may well help out here. It has ultra fast pixel access compared to TBitmap (The only downside is that, for speed reasons, the only supported format is 32bit bitmap). var x,y:integer; diff:integer; assert(bmp1.width=bmp2.width,'!'); assert(bmp1.height=bmp2.height,'!'); diff:=0; for y:=0 to bmp1.height-1 do for x:=0 to bmp1.width-1 do diff:=diff+abs(redcomponent(bmp1.pixel[x,y])-redcomponent(bmp2.pixel[x,y])); if diff>threshold then showmessage('Changed!'); You can speed it up even more by using pointers: var bmp1, bmp2: tbitmap32; p1, p2: PColor32; diff, x, y: integer; begin diff := 0; for y := 0 to bmp1.height - 1 do begin p1 := bmp1.PixelPtr[0, y]; p2 := bmp2.PixelPtr[0, y]; {Compare blue components to avoid shifts} for x := 0 to bmp1.width - 1 do begin diff := diff + abs(p1^ and $FF - p2^ and $FF); inc(p1); inc(p2); end; end; if diff > threshold then showmessage('Changed!'); end; Cheers, Nicholas Sherlock Back to top Paul Dunn Guest Posted: Fri Sep 02, 2005 9:33 am    Post subject: Re: Security camera image storage question. Nicholas Sherlock wrote: Quote: Dodgy wrote: So can anyone offer any suggestions on how to calculate a difference level between 2 images so I can check this against a threshold? Take a look at Graphics32 http://www.g32.org. I never leave home without it . It's a really fast graphic library that may well help out here. It has ultra fast pixel access compared to TBitmap (The only downside is that, for speed reasons, the only supported format is 32bit bitmap). If you manage to track down a copy of FastLIB (which appears to have vanished) you can work in any depth you like. FastLIB provides the same Pixel routines as an array offset into the DIB surface, and is blazingly fast. Another up-side is that the DIB surface is exposed as a flat array of bytes, so using BASM to write to it as you would any DDraw surface is trivial. I write a lot of very graphically intensive code, and found FastLIB to be better than Graphics32 when working with offscreen directdraw surfaces - as you can use whichever bit depth the user prefers for their desktop. [warning, rambling ahead] However, if you're wanting to work with graphics at a reasonable speed and don't like to dip into assembly, then you might consider a C/C++ compiler - Delphi's compiler can often bite you in the bum with some very sub-optimal code. This may have changed with Delphi 2005, but my tests indicate that Borland have only stepped around the compiler crapness by providing inline code rather than addressed it directly. On the other hand, most apps don't *need* fantastic speed except at certain points, and making the jump to C/C++ purely for performance reasons might be a bad idea when weighed up against the fact that Delphi is easier to code, and only occasionally needs assembly. My app BASin (http://homepage.ntlworld.com/paul.dunn4/BASin_r12.exe, contains *DELPHI 5* source - tested under Delphi 2005, but that version of Delphi has issues) is an example - the user interface is written in Delphi (and badly at that) but the z80 emulation core (FastCore.pas) is extremely fast - written in BASM for the main as many z80 opcodes can be translated into one or two x86 opcodes which you'd find extremely difficult to do in pure Delphi-pascal. That said, it's the only win32-based z80 core that runs on a 50mhz 486. Any optimisations that people can offer would be gratefully accepted... I'm not too proud of much of my code, but some of it I love. The UpdateDisplay() procedure in FastCore.pas is an example of working with a FastLIB surface in assembly. And yes, it *is* a Development environment for a 20 year old obsolete computer :-) Crikey, that didn't manage to stay on-topic for long, did it? D. Back to top J French Guest Posted: Fri Sep 02, 2005 12:46 pm    Post subject: Re: Security camera image storage question. On Thu, 01 Sep 2005 16:18:25 +0100, Dodgy <Dodgy (AT) earth (DOT) planet.universe> wrote: Quote: On Thu, 1 Sep 2005 16:29:23 +0200, "Maarten Wiltink" [email]maarten (AT) kittensandcats (DOT) net[/email]> waffled on about something: "Dodgy" <Dodgy (AT) earth (DOT) planet.universe> wrote in message news:2fudh1tue1jhpg7ch9gbn66jem5dnf3fvc (AT) 4ax (DOT) com... I've got a blank and white low light security camera hooked up to a WinTV card and I'm happily capping images every second onto the hard drive. Interesting problem Comparing bitmaps is a bitch In this case I would think sideways - what you want is a film show of activity, and nothing but confirmation when there is no activity Rig up some motion sensors and let the system go wild when there is activity - otherwise let it just write a date/time click and a visual every minute (or longer) I'm not keen on your data storage mechanism - it is rational - but will bite you in the but Just append the JPGs to one large file - open, store, close Back to top Dr John Stockton Guest Posted: Fri Sep 02, 2005 5:58 pm    Post subject: Re: Security camera image storage question. JRS: In article <ah6eh1942ul4448imb6hvmakgfqlav8jf0 (AT) 4ax (DOT) com>, dated Thu, 1 Sep 2005 16:18:25, seen in news:comp.lang.pascal.delphi.misc, Dodgy <Dodgy (AT) earth (DOT) planet.universe> posted : Quote: Yes it is a stationary camera, it looks at a door. I tried dropping the capture rate, but found 1 a second is the best minimum that guarantees a good mug shot of anyone coming through the door. Calculate the average of the picture, for each of the primary colours. Store images while the colour is changing significantly faster than usual. You can check this by dressing in suitable clothes and walking through the door. Of course, if it's *your* door, you could paint it and/or its background a helpful colour or fit a microswitch by a hinge. -- © John Stockton, Surrey, UK. *@merlyn.demon.co.uk / ??.Stockton (AT) physics (DOT) org © Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links. Correct <= 4-line sig. separator as above, a line precisely "-- " (SoRFC1036) Do not Mail News to me. Before a reply, quote with ">" or "> " (SoRFC1036) Back to top Darius Blaszijk Guest Posted: Sat Sep 03, 2005 12:06 am    Post subject: Re: Security camera image storage question. On Fri, 02 Sep 2005 18:58:23 +0100, Dr John Stockton wrote: Quote: Calculate the average of the picture, for each of the primary colours. Store images while the colour is changing significantly faster than usual. You can check this by dressing in suitable clothes and walking through the door. To increase the processing speed, you can also consider clipping a rectangle from the picture. Just check within a certain area. Make a diff of the area and if more than x percent of the image differs with more than a certain threshold (to eliminate noise) than store the images. HTH Darius Blaszijk Back to top Michal Borsuk Guest Posted: Sat Sep 03, 2005 6:55 am    Post subject: Re: Security camera image storage question. Dodgy wrote: Quote: Hi all, So what I want to do now, to reduce disk storage and aid detection, is to do some comparison between the image I just capped, and the image I capped a second before, and only if I have enough of a difference, write the image file to the disk. This is what movie compression does (MPEG2, DivX etc.). I only know that from the theory side, but how about trying to create acompressed avi with those frames? You'd solve the problem going through images as well. Just need to add date+time to the image. Quote: Cheers Dodgy. -- Michal Borsuk Advanced Call Manager - a call register and manager. http://www.advancedcallmanager.com/ Back to top Bob Swart Guest Posted: Sun Sep 04, 2005 6:31 am    Post subject: Re: Security camera image storage question. Hi Dodgy, Quote: So can anyone offer any suggestions on how to calculate a difference level between 2 images so I can check this against a threshold? I've done this for a webcam, and wrote about it for The Delphi Magazine (www.TheDelphiMagazine.com) in issue #109. You can download the source code from http://www.drbob42.com/tdm My algorithm compared the individual R G and B values of the two pictures against each other. Note that for a 640 x 480 bitmap, a number of pixels may be different without any actual motion being detected (especially when watching something that includes sunlight and shades - like my garden). So I had to add a minimum diff constant, to ignore small changes as motion... Basically, the code to compare was: for y:=0 to CaptureHeight-1 do begin for x:=0 to CaptureWidth-1 do begin NewRGB.RGBColor := ColorToRGB(CaptureImage.Picture.Bitmap.Canvas.Pixels[x,y]); OldRGB.RGBColor := ColorToRGB(PreviousImage.Picture.Bitmap.Canvas.Pixels[x,y]); if (abs(NewRGB.R - OldRGB.R) > $F) and (abs(NewRGB.G - OldRGB.G) > $F) and (abs(NewRGB.B - OldRGB.B) > $F) then Inc(diff); end Note that I'm also using a $F value as ignorable difference between the R, G and B values in the first place, otherwise the compare was too sensitive. It works fine on the webcam in my garden, which doesn't get triggered by movement of leaves, but does get triggered when our cat enters the view. Quote: Dodgy. Groetjes, Bob Swart (aka Dr.Bob - www.DrBob42.com) -- Bob Swart Training & Consultancy (eBob42) - Borland Technology Partner Delphi 2005 PDF manuals available from http://www.drbob42.com/training Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.