Unable to convert sets of PNG or BMP images, but can TGA and JPEG

When trying to convert a set of PNG image, the colors of the output OGV file become badly messed-up - see the attachment for an example. The input files for this example can be found at http://media.xiph.org/BBB/BBB-360-png/ and the example output should be similar to http://media.xiph.org/BBB/BBB-360-png/big_buck_bunny_00080.png

Also the output file size becomes abnormally huge - 4.7 MB for 100 frames.

The command that gives this result is:
    ffmpeg2theora bbb/big_buck_bunny_0%04d.png -o bbb.ogv

When doing a similar command with a set of BMP image, the program quits with a small and useless output file and the following error:

    [bmp @ 0x12ecf40]declared file size is less than header size (0 < 54)
        Last message repeated 7 times
    [image2 @ 0x12eb8e0]MAX_READ_SIZE:5000000 reached
    Input #0, image2, from 'bmp/frame%04d.bmp':
      Duration: 00:00:04.04, start: 0.000000, bitrate: N/A
        Stream #0.0: Video: bmp, yuv420p, 25 fps, 25 tbr, 25 tbn, 25 tbc
    picture size invalid (0x0)
    Could not set keyframe interval to 64.
    Internal Theora library error.

I'm using the binary "ffmpeg2theora-0.26.linux64.bin".

Conversion of TGA, JPEG and TIFF image sets works as expected.