ADAPTIVE FORWARD DIFFERENTIAL APPARATUS AND METHOD FOR DISPLAYING CURVE ON DISPLAY DEVICE BY STARTING DISPLAY ELEMENT FOR FORMATION OF CURVE

摘要

PURPOSE: To display accurately a high degree curve and a high degree curved face on a display device by providing a means receiving plural data points representing display elements forming a video image and a means displaying the curve incrementally in nearly uniform 1-pixel step. CONSTITUTION: An adaptive forward difference unit(AFDU) circuit 12 provides an output of a current X coordinate to a multiplier 20, in which the current X coordinate is multiplied by a corresponding 1/w value outputted from a 1/w circuit 18. Thus, the current X/w is fed to a pixel filter 30. Similarly Y/w and Z/w are are fed to the pixel filter 30 from AFDU circuits 10, 14, 16, the 1/w circuit 18 and multipliers 22, 24. Thus, X, Y, Z coordinates of a rational cubic function are outputted to the pixel filter 30 and a video image of the rational cubic function is used to select a pixel to be formed on a CRT. Thus, a high degree curve or curved face is accurately displayed.