An image acquisition apparatus for acquiring an image of a document including a housing having an internal space, a substantially transparent window, a CCD sensor array, a light source for illuminating the document and an opaque cover device for blocking light from escaping the internal space of the housing through the transparent window. The cover device includes an opaque wall that combined with the document, operationally blocks the escaping of light from the internal space of the housing. The cover device further includes a primary insertion slit, a document removing mechanism and a removal slit for removing a small form document through the removal slit. Optionally, the cover device further includes a second insertion slit for inserting the small form document. The width of the second insertion slit is smaller than the width of the first insertion slit.