The present invention relates to the data processing method and the data processing apparatus thereof.
In case of applying X-ray Computed Tomography (hereinafter referred to as X-ray CT) to non-contact internal dimensional measurement, various kinds of three-dimensional image processing are applied to the three-dimensional bit map data obtained by stacking multi-layered tomographic images defined as two-dimensional bit map data. This technology is used in the medical field, and described in the publication (for example, Three-dimensional image processing in Medical Science by Yasuzo Shuudou, Corona Publishing Co., 1995).
In many cases, for various kinds of data processing for three-dimensional image processing, the following procedures are used. That is, the user supplies commands to the program and the program in response to those commands processes the data (this is called interactive).
In this interactive process, it is required to minimize the user""s additional operations due to his or her erroneous operation. For this reason, many programs provides an undo (data and/or operation recovery) function. This function means that the data before processing is stored temporarily, and the data after processing is replaced by the data before processing when the undo command is issued. The user who has noticed his or her erroneous operation can cancel his or her latest operation by inputting the undo command and restart his or her operation from this point. If several sets of data before processing could be stored temporarily, the user can cancel several latest operations backward and restart the operation at any point.
In association with the function described above, Japanese Patent Laid-Open Number 6-251078 (1995) discloses an information processing apparatus in which scale-down image data corresponding to the image data represented as bit map data are arranged and the list of scale-down image data are shown and made selected. Japanese Patent Laid-Open Number 6-202612 (1995) discloses a graphic editor apparatus which provides a display part having a display area for the image edition allowing the user to edit the image and a target object image display area for displaying plural screens of the images in process of edition work.
The prior art described above does not consider the processing of large amount of three-dimensional bit map data over several hundreds megabyte obtained by the high resolution X-ray CT (in this specification, the data having the volume between 100 megabyte and 1 Peta byte is called large amount of data). In many cases, the volume of data is limited below 1P (1 Peta byte) because the technical difficulty occurs in dealing large amount of data.
The volume of the three-dimensional bit map data is proportional to the cubic of the long dimension of the image. A direct application of the apparatus disclosed in Japanese Patent Laid-Open Number 6-251078 (1995) and the conventional method used for three-dimensional bit map operation in the conventional practical field of medical science may arise some problems.
According to the original experiment by the inventors, in case of dealing such large amount of three-dimensional bit map data, it is understood that it takes 10 minutes or longer to display fully the data even by the current computer performance. This is because the image processing called rendering is required to display the three-dimensional bit map data, and it may take an extended time to complete this operation in case that the volume of data is too large. From the user""s view, in case of displaying the data in order to confirm the content of the data, such an extended time is required for processing the individual data file in order to browse the content of the individual data.
In case of applying the technology disclosed in Japanese Patent Laid-Open Number 6-251078 (1995) to the three-dimensional bit map data used in the field of medical science, as the time spent in generating the scale-down bit map data from the three-dimensional bit map data (in this case, the volume of data is relatively small) is longer than the time spent for rendering the original three-dimensional bit map data and displaying the resulting image, the time required for confirming the content of the file does not make any significant problem.
In the method for generating the scale-down data of the overall data set later on to be used for search, as disclosed in Japanese Patent Laid-Open Number 6-251078 (1995), there is such a problem that the scale-down operation for the data is required to be done by the user.
In the process of large amount of three-dimensional bit map data, its process itself gives rise to a problem. There may be such a condition that the memory space runs short if the data is stored in the memory every time when the process is repeated. Thus, the number of undo operations (the number of allowable operations to be cancelled) is limited.
In such a method that the rendering operations is performed and the data is displayed every time when the undo command is issued, if the number of undo operations is larger, the fraction of the total waiting time for the user occupied in the overall operation time becomes extremely long because it takes an extended time to be spent for display process.
An object of the present invention is to provide a data processing method and its processing apparatus enabling to display an preview image rapidly in case of processing large amount of data.
In order to attain the above object, in the present invention, index data are generated by rendering the large amount of bit map data and stored in addition to the three-dimensional bit map data.
It is required to render the large amount of bit map data in order to generate a display image. The rendering process requires an extended period of time. On the contrary, by means that the two-dimensional image resulted from the rendering process is made prepared in advance before accepting the user""s command for display and edit, the preview of the content of the data can be displayed rapidly at real-time when the user issues the command interactively.