The GlyphReader engine has an internal restriction on the size of the image it can process. The maximum size is 11,999x11,999 pixels. An attempt to pass an image larger than this to the engine will result in one of the following exceptions being thrown.
ERROR 1029, Source Image is too wide
ERROR 1030, Source Image is too long
The GlyphReader engine has pre-processing options that may re-size the image internally. If you are using the pre-processing options, you want to leave a bit of a cushion so the internal resizing will not cause the exception to be raised(a few hundred pixels in each dimension should be sufficient).
Attached is a custom image source which internally restricts the size of the image that will be passed to the OCR engine. The max size is set at 10,000 pixels, you may to increase or decrease this depending on the pre-processing options you have enabled.