Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!news.swapon.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Jolly Roger Newsgroups: comp.sys.mac.system Subject: Re: Any quick, easy way to compare two images? Date: 26 Jan 2014 15:43:39 GMT Organization: People for the Ethical Treatment of Pirates Lines: 73 Message-ID: References: <2ridndio-M0kOnzPnZ2dnUVZ8kmdnZ2d@giganews.com> <2fd2jijlbb.fsf@ethel.the.log> <161tzyjibp.fsf@ethel.the.log> <5cKdnS2-vfr0cX_PnZ2dnUVZ_oSdnZ2d@giganews.com> <6jy523synp.fsf@ethel.the.log> <250120141345247892%nospam@nospam.invalid> <250120141630000472%nospam@nospam.invalid> <2014012515592033890-savageduck1@REMOVESPAMmecom> <2014012517510124273-savageduck1@REMOVESPAMmecom> X-Trace: individual.net SHAwziQWsQThgHF7lEfyJQdjSZQzT8UZcTnjN6H2sggBgDcdOg Cancel-Lock: sha1:pj4hqtVb4g+BaTDHsHzBfEczDmA= X-Face: _.g>n!a$f3/H3jA]>9pN55*5<`}Tud57>1Y%b|b-Y~()~\t,LZ3e up1/bO{=-) User-Agent: slrn/1.0.1 (Darwin) Xref: csiph.com comp.sys.mac.system:55430 On 2014-01-26, Don Bruder wrote: > In article <2014012517510124273-savageduck1@REMOVESPAMmecom>, > Savageduck wrote: > >> If you are doing this project as some sort of time lapse photography >> exercise, then each frame SHOULD be unique just based on capture time. >> Why would you not trust your camera to capture the images one at a >> time? > > Did *ANYBODY* who's still nit-picking at this thread actually *READ* my > initial post and the clarification in response to "nospam" back at the > start of this thread? I did my best to explain things so that between > the two, I thought it should be all but impossible to not understand > what I'm doing. (I thought the first one alone was pretty clear, but > considering the East Elbonian clusterfuck this thread has turned into...) > > Here - eyeball it yourself: > > What follows is the body of the message I'm talking about. Or, retrieve > it yourself - Message-ID: [snip] You say: "I'm messing with an app to assemble a stream of webcam images into a crude stop-motion movie." and that you need "a routine that returns a YES/NO to the question "Is NewImage the same as PreviousImage"". Then later you say: "I want to grab every available image, but NOT grab umpty-nine copies of an image that's been sitting there for who-knows-how-long" The reason we are still talking about this is you have not sufficiently articulated what you want. In your OP, you seem to imply that this network camera captures images of a scene at irregular intervals, and that you have a collection of those images that you want to process to eliminate captures of the scene that are not substantially different. What you have failed to do, as far as I am aware, is explain how any of those images are what you consider to be "duplicates", nor what you would consider to be "different". I have such network cameras in my home right now. I have some hand-written software that polls them whenever I leave the house to capture images from the cameras and store them on a file server, and then later create a QuickTime movie consisting of a stream of those captured images. From one moment to the next, there may be multiple image file snapshots of that scene. These are distinctly different image captures of a scene that is not changing by much. So I end up with a stream of images that capture a scene over a time span. And while I can visually see with my eye that not much in the scene changed, the images (due to JPEG compression artifacts, ISO noise, and other factors such as natural lighting changes) are distinctly different such that a simple comparison algorithm such as diff will report that all of the imags are different, which will not tell me whether the changes are worth my attention. So I use a piece of software called motiontrack to compare the images in such a way that allows me to assign a threshold to each comparison representing the amount of change in the scene I am willing to allow before I take action. If scenes that appear similar to the naked eye yet have no interesting changes is what you consider to be an unwanted "duplicate image", that's one thing. But if you are saying that somehow you are getting perfect replica duplicate images somehow, that's a whole different thing. So you really need to clarify this. Which is it, really? -- E-mail sent to this address may be devoured by my ravenous SPAM filter. I often ignore posts from Google. Use a real news client instead. JR