| 摘要 |
<p>PURPOSE: To set a quantizing table with simple processing by selecting one of plural quantizing tables for two-dimensional image based on a feature amount corresponding to the dispersion of respective picture element values. CONSTITUTION: Three kinds of quantizing tables are prepared as initial setting. Next, sampling is executed for thinning the picture elements of a source image as preprocessing. After sampling, the feature amount corresponding to the dispersion of picture element values such as the difference (absolute value) between adjacent picture element values, for example, is calculated. Next, the respective calculated differential values are compared with a threshold value, and the number of differential values exceeding the threshold value is counted. Further, the quantizing table is selected based on this calculated numerical value. Concerning a numerical value in the parentheses of a column for initial setting, when the numerical value calculated like this is equal with that numerical value in the parentheses, the correspondent quantizing table is selected. Thus, the quantizing table suitable for the source image is selected, the characteristics of the image can be grasped by simple operation and the suitable quantizing table suited to the characteristics of that image can be selected.</p> |
