Well I've worked something out. If the CGContext supplied buffer that the CIContext draws the results of the CIAreaMaximum filter to uses float components it doesn't work. Providing a context which is 8 bit ints per component with 4 components RGBA works.
Not the result I wanted, but at least I have something that works even thoug I lose some dynamic range. Kevin On 26 Feb 2014, at 12:50, Kevin Meaney <[email protected]> wrote: > I've written a command line routine that compares two image files, in the > hope of determining if the two files are different. Basically the tool only > compares whether the dimensions are different or whether the pixel values are > sufficiently different. So the routine has a distance option which is a > threshold value over which any color component of any pixel needs to be over > to decide if the images are different. > > The full single file source code for this is available here: > https://gist.github.com/SheffieldKevin/9228574 > > To implement this I've used two CIFilters, first the CIDifferenceBlendMode > filter followed by the CIAreaMaximum. > > I've checked that the CIDifferenceBlendMode is working by grabbing the > outputImage CIImage from the filter and saving it in a file on the desktop > called deleteme.png. If you look at the code you'll see that the code for > saving the intermediate image is still in there. If you compile and run you > can setup the command line args similar to: > > compareimages -file1 "~/Pictures/DSCN1003.JPG" -file2 > "~/Pictures/DSCN1004.JPG" > > The color distance option has a default value so is not required. > > The intermediate image looks as expected so I'm assuming that the problem has > to be with how I'm using the CIAreaMaximum filter. > > Can anyone point me in the direction as to what it is I'm doing wrong? > > Kevin > > > _______________________________________________ > > Cocoa-dev mailing list ([email protected]) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/ktam%40yvs.eu.com > > This email sent to [email protected] _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
