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Groups > comp.sys.mac.system > #55221
| From | nospam <nospam@nospam.invalid> |
|---|---|
| Newsgroups | comp.sys.mac.system |
| Subject | Re: Any quick, easy way to compare two images? |
| Date | 2014-01-23 14:24 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <230120141424174937%nospam@nospam.invalid> (permalink) |
| References | <lbrnpr$q5o$1@dont-email.me> |
In article <lbrnpr$q5o$1@dont-email.me>, Don Bruder <dakidd@sonic.net>
wrote:
> Long story short, I'm messing with an app to assemble a stream of webcam
> images into a crude stop-motion movie.
>
> Since the images may arrive at irregular intervals, I'd like to be able
> to do something similar to this:
>
> NSImage *PreviousImage; // Global to the class
>
> -(NSImage *)getNewImage:(NSString *)ImageSourceURL
> {
> NSImage *NewImage = [self grabImageFrom:ImageSourceURL];
> if (MAGIC)
> {
> // Yes, it's a new image
> if (PreviousImage)
> [PreviousImage release]; // Dump the old one, if any
> PreviousImage = [NewImage copy]; // replace with new one
> return NewImage; // and send the new one back to caller
> }
> else
> // Nope, image hasn't changed.
> return nil;
> }
>
> Where "MAGIC" needs to be a routine that returns a YES/NO to the
> question "Is NewImage the same as PreviousImage"?
>
> Is there a reasonably painless cocoa/core foundation way to do this, or
> am I stuck going right down onto the metal and doing a pixel-by-pixel
> comparison "by hand"?
>
> From what I've managed to find in the various cocoa docs, it *LOOKS* as
> though the "compare" type methods I can spot decide on equality by
> saying "Is this *POINTER* to an NSImage the same as this *OTHER POINTER*
> to an NSImage?", without actually looking at the images themselves -
> only the pointers to them. Which makes it look as though, should I
> assign two identical images to two different NSImages, they'll compare
> "not the same", despite the fact that they're identical. Or am I
> mis-reading things?
the default comparison is by pointer, so you'd need to write your own
equality (and hash) methods. how would it know what you consider
'equal' ? it can't.
also keep in mind that the camera won't produce pixel identical results
on every frame, even when nothing has changed, so you can't just loop
through all pixels and compare. the values will vary slightly.
this is also something that's been solved before, so you probably can
find existing image matching or motion detection code.
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Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 10:42 -0800
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-23 14:24 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 13:00 -0800
Re: Any quick, easy way to compare two images? Tom Stiller <clusterfux.upmon@gmail.com> - 2014-01-23 21:11 +0000
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 16:38 -0800
Re: Any quick, easy way to compare two images? john hevelin <bwotte@panix.com> - 2014-01-24 01:57 +0000
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-23 18:03 -0800
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 21:25 -0800
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-23 16:31 -0500
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-23 16:57 -0500
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-23 17:02 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 21:28 -0800
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-23 16:32 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 16:22 -0800
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-23 19:48 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 23:54 -0800
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-24 08:09 -0800
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-24 08:44 -0800
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-23 22:06 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-23 23:37 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-23 20:46 +0000
Re: Any quick, easy way to compare two images? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-01-23 23:19 +0000
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-23 18:38 -0500
Re: Any quick, easy way to compare two images? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-01-24 00:49 +0000
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-23 19:59 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-23 15:25 -0800
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-23 18:37 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-23 16:05 -0800
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-23 19:47 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-23 17:10 -0800
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-24 17:42 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-24 16:42 -0800
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-24 20:08 -0800
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-25 10:54 -0500
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 15:31 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-25 17:31 -0800
Re: Any quick, easy way to compare two images? Michael Vilain <vilain@NOspamcop.net> - 2014-01-25 17:57 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 03:09 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 23:02 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 05:04 +0000
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-25 10:58 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-25 10:29 -0800
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-25 13:39 -0500
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 13:45 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-25 13:27 -0800
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 16:30 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-25 13:33 -0800
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 16:52 -0500
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 17:31 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-25 22:35 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 17:49 -0500
Re: Any quick, easy way to compare two images? Tom Stiller <clusterfux.upmon@gmail.com> - 2014-01-25 22:55 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 18:33 -0500
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 19:42 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-25 17:38 -0800
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 22:50 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 02:49 +0000
Re: Any quick, easy way to compare two images? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-01-26 14:21 +0000
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 15:17 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-26 14:04 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 00:17 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 19:42 -0500
Re: Any quick, easy way to compare two images? dorayme <do_ray_me@bigpond.com> - 2014-01-26 12:23 +1100
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 02:54 +0000
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 02:52 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 22:10 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 03:32 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 22:55 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 05:02 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-26 14:04 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-25 18:03 -0800
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 22:10 -0500
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 17:49 -0500
Re: Any quick, easy way to compare two images? Savageduck <savageduck1@{REMOVESPAM}me.com> - 2014-01-25 15:59 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 00:24 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 19:42 -0500
Re: Any quick, easy way to compare two images? Savageduck <savageduck1@{REMOVESPAM}me.com> - 2014-01-25 17:30 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 02:57 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 22:46 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 03:49 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 22:55 -0500
Re: Any quick, easy way to compare two images? dorayme <do_ray_me@bigpond.com> - 2014-01-26 12:08 +1100
Re: Any quick, easy way to compare two images? Savageduck <savageduck1@{REMOVESPAM}me.com> - 2014-01-25 17:31 -0800
Re: Any quick, easy way to compare two images? dorayme <do_ray_me@bigpond.com> - 2014-01-26 13:00 +1100
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-25 20:13 -0800
Re: Any quick, easy way to compare two images? dorayme <do_ray_me@bigpond.com> - 2014-01-26 16:15 +1100
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-25 18:07 -0800
Re: Any quick, easy way to compare two images? Savageduck <savageduck1@{REMOVESPAM}me.com> - 2014-01-25 18:24 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 02:58 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 22:10 -0500
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-25 17:36 -0800
Re: Any quick, easy way to compare two images? Savageduck <savageduck1@{REMOVESPAM}me.com> - 2014-01-25 17:51 -0800
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-26 00:39 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 15:43 +0000
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-26 08:19 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 16:31 +0000
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-26 09:54 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 18:14 +0000
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-26 10:44 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 19:10 +0000
Re: Any quick, easy way to compare two images? dorayme <do_ray_me@bigpond.com> - 2014-01-27 11:14 +1100
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-26 16:22 -0800
Re: Any quick, easy way to compare two images? dorayme <do_ray_me@bigpond.com> - 2014-01-27 11:44 +1100
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-27 13:06 -0500
Re: Any quick, easy way to compare two images? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-01-27 12:48 +0000
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-27 05:49 -0800
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-26 12:05 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 17:08 +0000
Re: Any quick, easy way to compare two images? Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-01-26 12:27 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 17:37 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-26 15:36 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 21:46 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-26 14:04 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-26 12:16 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 21:47 +0000
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-26 16:21 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-27 01:57 +0000
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-26 10:32 -0800
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 18:54 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-26 15:40 -0500
Re: Any quick, easy way to compare two images? Savageduck <savageduck1@{REMOVESPAM}me.com> - 2014-01-26 13:30 -0800
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-26 15:06 -0800
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-26 18:20 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 23:35 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-27 13:06 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-27 19:14 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-27 23:18 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-28 04:27 +0000
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-29 14:01 -0500
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-29 14:01 -0500
Re: Any quick, easy way to compare two images? john hevelin <bwotte@panix.com> - 2014-01-27 01:19 +0000
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-26 18:28 -0800
Re: Any quick, easy way to compare two images? john hevelin <bwotte@panix.com> - 2014-01-28 02:26 +0000
Re: Any quick, easy way to compare two images? Don Bruder <dakidd@sonic.net> - 2014-01-28 06:35 -0800
Re: Any quick, easy way to compare two images? dorayme <do_ray_me@bigpond.com> - 2014-01-27 10:55 +1100
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-25 22:10 -0500
Re: Any quick, easy way to compare two images? Doug Anderson <ethelthelogremovethis@gmail.com> - 2014-01-25 21:41 -0800
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-26 14:04 -0500
Re: Any quick, easy way to compare two images? Jolly Roger <jollyroger@pobox.com> - 2014-01-26 03:13 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 17:30 -0500
Re: Any quick, easy way to compare two images? john hevelin <bwotte@panix.com> - 2014-01-25 18:51 +0000
Re: Any quick, easy way to compare two images? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-01-25 19:06 +0000
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 15:37 -0500
Re: Any quick, easy way to compare two images? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-01-25 15:35 -0500
Re: Any quick, easy way to compare two images? nospam <nospam@nospam.invalid> - 2014-01-23 22:06 -0500
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