Image reading apparatus determining edge of original document

A non-transitory computer-readable storage medium storing computer-readable instructions that, when executed by a controller, causes an image reading apparatus that comprises:

• a conveying unit configured to convey an original document toward a reading position on a conveying path, the original document including a leading edge and a trailing edge;
• an image reading unit having a reading region, and configured to perform a reading operation while conveying the original document to generate image data representing an image corresponding to the reading region, the reading region extending in a main scanning direction and being positioned at the reading position, the reading region including a first region and a second region adjacent to the first region, the image data including first data and second data, the first data representing an image corresponding to the first region, the second data representing an image corresponding to the second region, the original document passing through the first region and not passing through the second region;
• an opposing member opposing the image reading unit and extending over the reading region, the original document passing a space between the image reading unit and the opposing member;
• and a displacing unit configured to displace the opposing member farther away from the image reading unit when the original document is present in the reading region than a position of the opposing member when the original document is not present in the reading region, to perform
• executing the reading operation while conveying the original document and generating image data representing an image defined by the reading region;
• and
• determining that one of the leading edge and the trailing edge reaches the reading position when the second data satisfies a prescribed condition.