HP 48gII hp 48gII_user's manual_English_E_HDPMSG48E67_V2.pdf - Page 746

Graphic objects (GROBs) The word GROB stands for GRaphics OBjects and is used in the calculator's environment to represent a pixel-by-pixel description of an image that has been produced in the calculator's screen. Therefore, when an image is converted into a GROB, it becomes a sequence of binary digits (binary digits = bits), i.e., 0's and 1's. To illustrate GROBs and conversion of images to GROBS consider the following exercise. When we produce a graph in the calculator, the graph become the contents of a special variable called PICT. Thus, to see the last contents of PICT, you could use: PICT RCL(„°L@)PICT @PICT „©). The display shows in stack level 1 the line Graphic 131×64 (if using the standard screen size) followed by a sketch of the top part of the graph. For example, If you press ˜ then the graph contained in level 1 is shown in the calculator's graphics display. Press @CANCL to return to normal calculator display. The graph in level 1 is still not in GROB format, although it is, by definition, a graphics object. To convert a graph in the stack into a GROB, use: 3` „°L@)GROB @ GROB . Now we have the following information in level 1: The first part of the description is similar to what we had originally, namely, Graphic 131×64, but now it is expressed as Graphic 13128 × 8. However, the graphic display is now replaced by a sequence of zeroes and ones representing the pixels of the original graph. Thus, the original graph as now been converted to its equivalent representation in bits. Page 22-30