Thanks for this information guys, it really helped. I also answered my question on SO: http://stackoverflow.com/questions/11081806/larger-memory-footprint-when-using-bitmapfactory-decodefile-in-c-sharp-and-huge/11084422#11084422
Thanks Matthew On Mon, Jun 18, 2012 at 1:52 PM, Tomasz Cielecki <tom...@ostebaronen.dk>wrote: > As Darren said, loading a bitmap into memory decompresses it and > depending on what bitmap config you load it with it will take up more > memory than its compressed size on disk. > > Take a look at > http://developer.android.com/reference/android/graphics/Bitmap.Config.html > > http://androidapi.xamarin.com/?link=T%3aAndroid.Graphics.Bitmap%2bConfig%2f* > > You have the possibility of loading the bitmap with 2 bits per pixel > or 4 bits per pixel either with or without the alpha channel. > > A good idea if you are going to work with large image sizes which are > bigger than the screen bounds you probably want to scale that image > before displaying it on screen: > > http://docs.xamarin.com/android/recipes/Resources/General/Loading_Large_Bitmaps_Efficiently > > On Mon, Jun 18, 2012 at 1:34 PM, Darren Abbott <dar...@darrenabbott.com> > wrote: > > How are you measuring the memory usage? Could you be including the Mono > run > > time in the C# calculation? > > > > The images you are loading are jpg compressed. Bitmap is an uncompressed > > format. A little Googling showed a typical JPEG compression ratio of > 10:1 > > to 20:1 without losing noticeable image quality. 60KB -> 1 MB is in that > > range. > > > > Darren > > > > On Jun 18, 2012 6:06 AM, "Matthew Leibowitz" <mattleibowm...@gmail.com> > > wrote: > >> > >> Hi all, > >> > >> > >> I just want to see if anyone else has noticed that when loading images > >> into memory, the exact same C# code uses more memory to hold the images > >> (~1.5x the amount in Java). > >> > >> This Java code results in a total memory size of 105.5 MB: > >> > >> Bitmap[] bitmaps = new Bitmap[100]; > >> > >> for (int i = 0; i < 100; i++) > >> { > >> String root = > >> Environment.getExternalStorageDirectory().getAbsolutePath(); > >> String imagePath = "/evolution/threesixty/216/Edaphosaurus_001.jpg"; > >> > >> bitmaps[i] = BitmapFactory.decodeFile(root + imagePath); > >> } > >> > >> This C# code results in 148.1 MB: > >> > >> Bitmap[] bitmaps = new Bitmap[100]; > >> > >> for (int i = 0; i < 100; i++) > >> { > >> string root = Environment.ExternalStorageDirectory.AbsolutePath; > >> string imagePath = "/evolution/threesixty/216/Edaphosaurus_001.jpg"; > >> > >> bitmaps[i] = BitmapFactory.DecodeFile(root + imagePath); > >> } > >> > >> Does anyone have any ideas as to why? I understand that the .NET > wrappers > >> may use a little more to hold extra binding data or things, but surely > not > >> that much? > >> > >> Also, as a side question: > >> Each image is only 60 KB on disk, why is the in-memory version 1 MB? I > >> know that my loading method does not do any sampling/density checking, > but > >> that was not the aim. Surely loading a <100KB image should not exceed > 100KB > >> memory space? > >> > >> > >> Regards, > >> Matthew > >> > >> _______________________________________________ > >> Monodroid mailing list > >> Monodroid@lists.ximian.com > >> > >> UNSUBSCRIBE INFORMATION: > >> http://lists.ximian.com/mailman/listinfo/monodroid > >> > > > > _______________________________________________ > > Monodroid mailing list > > Monodroid@lists.ximian.com > > > > UNSUBSCRIBE INFORMATION: > > http://lists.ximian.com/mailman/listinfo/monodroid > > > > > > -- > Med Venlig Hilsen / With Best Regards > Tomasz Cielecki > http://ostebaronen.dk > _______________________________________________ > Monodroid mailing list > Monodroid@lists.ximian.com > > UNSUBSCRIBE INFORMATION: > http://lists.ximian.com/mailman/listinfo/monodroid >
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