Preventing the Formation of Stripes in Greytone Image Representations in Dot Printers With Irregular Paper Advance
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
To prevent the formation of horizontal stripes, caused by undesirable irregular paper advance, in particular in the case of mean grey values, a field of threshold value matrices is predetermined for image representations in all-points-addressable dot printers, such as electroerosion printers. In these matrices, the cluster structures of a row are vertically shifted by + 1 pel (picture element) by means of a random generator. For the subsequent example, it is assumed for simplicity that a grey value scale of 0, 1, 2 ... 18 has been predetermined for scanning an original image of 3 x 6 surface elements. For reproducing the scanned image, the grey values may be represented by different cluster structures (for example, dot groups in a 3 x 6 dot matrix).