Method and apparatus for reading image of image scanner-reader

A method of reading an original document by an image scanner-reader having image read means and an image data buffer, said method comprising the steps of:

• reading an original document and producing image data of said original document;
• suspending an original document reading operation, if said image data buffer becomes full of data and cannot receive more data;
• and
• decreasing a relative moving speed between said original document and said image read means and restarting the original document reading operation and lowering a resolution of the image data only if the image data buffer is filled substantially to capacity.

An image scanner-reader for processing image data from an original document, and transmitting processed image data to a host device transmitting a command including a first image data resolution and transmitting an end signal, said image scanner-reader comprising:

• read means for reading the original document and producing image data at a second image data resolution;
• a screen buffer, coupled to the read means, for storing image data of the original document read by the read means;
• image processing means, coupled to the screen buffer, for processing the image data stored in said screen buffer at the second image data resolution and for producing processed image data at the first image data resolution;
• and
• control means, coupled to the read means, the screen buffer, and the image processing circuit, for controlling the image processing means to convert the image data at the second image resolution to the processed image data at the first resolution and for erasing the image data stored in said screen buffer in response to the end signal, wherein all instructions before the end signal are executed on the image data stored in said screen buffer.