It appears that the @BitmapToMat@ BitmapToMat function cannot open images that don't have the @Bitmap.Config.ARGB_8888@ Bitmap.Config.ARGB_8888 Config. Calling the function on images with other types, such as @RGB_565@, RGB_565, results in the @Mat@ Mat object having zero size and one channel. Using @Bitmap.copy@ Bitmap.copy to convert the image to @ARGB_8888@ ARGB_8888 before calling the function fixes the problem.

Here is an example log output for the source code I attached:
<pre>
$ adb logcat
08-06 03:18:21.506 18438 18438 D OpenBitmaps: /mnt/sdcard/Images/windsor_chair_0002.jpg: exists=true
08-06 03:18:21.506 18438 18438 D OpenBitmaps: /mnt/sdcard/Images/windsor_chair_0002.jpg: 300x180
08-06 03:18:21.506 18438 18438 D OpenBitmaps: /mnt/sdcard/Images/windsor_chair_0002.jpg: 0.0x0.0

</pre>
Android 2.3.3 was used. Here is the processor info:
<pre>
$ adb shell cat /proc/cpuinfo
Processor : ARMv7 Processor rev 2 (v7l)
BogoMIPS : 299.95
Features : swp half thumb fastmult vfp edsp neon vfpv3
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x3
CPU part : 0xc08
CPU revision : 2

Hardware : mapphone_CDMA
Revision : 0000
Serial : 0000000000000000
</pre>